10
Recovery

No material is wasted in a functioning ecosystem.

10.1 Principle 7

The degree of recovering water, energy, nutrient, and materials from wastewater (WW) reflects the sustainable level in EEIS design. In theory, almost all the wastewater (WW) could be recovered to reusable water because contaminants in WW is less than 0.1% by weight. However, not all the water could be recovered because water used in economy tend to dissipate within the economic system due to the second law of thermodynamics. In addition, energy resources are usually not recyclable. Energy would deteriorate to lower grade energy in addition to dissipation in the environments. Indeed, entropy would put a limit in designing recovery processes of EEIS. This irreversible energy degradation rate depends upon not only the ratio between the intensities of output and input flows but also the energy quality. Therefore, the ultimate decision whether to recover water, energy, nutrient, and materials from WW depends upon the life cycle cost and benefit analysis (LCCBA) of different alternatives. The prevention principle is illustrated in Box 10.1.

In nature, almost all the material, nutrients, and water are recycled. In modern society, however, the traditional environmental engineering design focuses on treatment and disposal. However, when the accumulation rate is significantly greater than the treatment capacity, waste would end in the environments without adequate treatment. If cost is not a limited factor, all materials could be recovered through environmental engineering infrastructure system as shown in Table 10.1.

Table 10.1 Recovery of materials and energy.

Design Problems Mass Energy
Air Landfill CH4 Bioreactor landfills CH4
Carbon dioxide from coal power plants Carbon sequestration Methanol
Water Nutrients N and P Struvite
Wastewater Reclaimed water CH4 or electricity
Land Soil erosion Regenerative GI Biomass
Ecological Algae boom Constructed wetlands Blue algae for biodiesel

To recover methane, landfills can be designed in such a way that they produce methane and is referred to as bioreactor landfill. WW contains nutrients such as N and P, energy as methane, and treated WW. For land, green infrastructure aims to maximize primary biomass production and reduce pollution of water bodies. Algae could be recovered from eutrophic lakes. For WW, most of the nitrogen are in soluble and colloidal organic forms. The amount removed by primary sedimentation is limited to about 15%, and activated sludge (AS) removes another 10%. Twenty‐five percentage of nitrogen removal equals about four percentage of the BOD applied. With a total reduction of only 25%, the effluent contains 26 mg/l nitrogen of the original 35 mg/l. Approximately 2 mg/l is organic nitrogen bound in the effluent suspended solids. The remaining 24 mg/l is in the form of ammonia, except when nitrification occurs during aeration. Figure 10.1 is a diagram tracing nitrogen through a hypothetical treatment plant. The nitrogen concentration in the influent WW is assigned a value of 100%. To recover energy, sludge is stabilized by anaerobic digestion, and the ammonia released from decomposition of the sludge solids is returned to the influent of the treatment plant in supernatant from the digester. Assuming 40% of the organic nitrogen in the sludge is converted to ammonia, 10% of the original 25% is recycled to the treatment plant and appears in the effluent, which then contains 85% of the influent nitrogen. Depending on variations in nitrogen content of the WW and methods of sludge processing, nitrogen removal in conventional biological treatment systems ranges from 20% up to 40%.

Diagram with an arrow (influent nitrogen) directing to primary settling then to biological aeration, to final settling. From final settling, arrow exits as effluent nitrogen.

Figure 10.1 Diagram tracing wastewater nitrogen through a hypothetical treatment plant.

10.2 Phosphorus Removal from Wastewater

The common forms of phosphorus in WW are orthophosphate (PO43−), polyphosphates (polymers of phosphoric acid), and organically bound phosphates. Polyphosphates such as hexametaphosphate gradually hydrolyze in water to the soluble orthoform, and bacterial decomposition of organic compounds also releases orthophosphate. With the majority of compounds in WW being soluble, phosphorus is removed only sparingly by sedimentation. Secondary biological treatment removes phosphorus by biological uptake; however, relative to the quantities of nitrogen and carbon, the amount of phosphorus is greater than necessary for biological synthesis. As a result, conventional treatment process removes only about 20–40% of the influent phosphorus.

10.2.1 Phosphorus Removal in Conventional Treatment

Phosphorus enters the sewer in the form of soluble and organically bound phosphates. Biological activity in the sewer releases organically bound phosphates into solution that are not removed by sedimentation. The amount of organically bound phosphates released into a soluble form varies with the sewer age, WW temperature, and biological conditions. Table 10.2 shows typical N and P forms in raw, primary, and secondary WW treatment. The total phosphorus is reduced from 7 to 6 mg/l by sedimentation. Secondary biological treatment removes phosphorus by biological uptake; however, the amount of phosphorus is surplus relative to the quantity of nitrogen and carbon necessary for synthesis. In general, the amount of phosphorus in the excess biological floc produced in activated sludge treatment of a WW is equal to about 1% of the BOD applied. For this reason, the total phosphorus is further reduced from 6 mg/l to approximately 5 mg/l.

Table 10.2 Approximate nutrient composition of average domestic wastewater and effluents.

Determinant Raw Primary Secondary
Organic content (mg/l)
Suspended solids 240 120 30
Biochemical oxygen demand 200 130 30
Nitrogen content (mg/l as N)
Inorganic nitrogen 22 22 24
Organic nitrogen 13 8 2
Total nitrogen 35 30 26
Phosphorus content (mg/l as P)
Inorganic phosphorus 4 4 4
Organic phosphorus 3 2 1
Total phosphorus 7 6 5

10.2.2 Chemical Phosphorus Removal

Chemical precipitation using aluminum or iron coagulants is effective in phosphate removal. Aluminum ions precipitate with phosphate ions as follows:

The molar ratio of Al to P is 1 : l and the mass ratio of commercial alum to phosphorus is 9.7 to l.0. Coagulation studies have shown that greater than this alum dosage be necessary to precipitate phosphorus from WW. One of the competing reactions, which accounts in part for the excess alum requirement, is the alum reaction with natural alkalinity as follows:

(10.2)images

As a result, 75, 85, and 95% phosphorus reductions require alum to phosphorus mass ratios of about 13 to 1, 16 to 1, and 22 to 1, respectively. For example, to achieve 85% phosphorus removal from a WW containing l0 mg/l of P, the alum dosage needed is approximately 16 × 10 = 160 mg/l, which is substantially greater than the 9.7 × 10 = 97 mg/l stoichiometric quantity of alum according to Reaction (10.1).

Iron coagulants precipitate orthophosphate by combining with the ferric ion as shown in Reaction (10.3) at a molar ratio of l to 1:

Similar to aluminum, a greater amount of iron is required in actual coagulation than this chemical reaction predicts. One of the competing reactions with natural alkalinity is

(10.4)images

If WW has sufficient natural alkalinity, ferric salts applied without coagulant aids result in phosphorus removal at Fe to P dosages of 1.8 to l.0 ratio or greater. This is equivalent to an application of approximately 150 mg/l of commercial ferric chloride for treatment of WW containing 10 mg/l of P. Since the reaction of ferric chloride with natural alkalinity is relatively slow, lime may be applied to raise the pH and supply the hydroxide ion for coagulation as follows:

(10.5)images

Ferrous sulfate also forms a phosphate precipitate with an Fe to P molar ratio of 1 : 1, and the dosages for coagulation are similar to ferric salts. Commercially available iron salts are ferric chloride, ferric sulfate, ferrous sulfate, and waste pickle liquor from the steel industry. For the purpose of recycle and reuse, pickle liquors with either sulfuric or hydrochloric acid are the two common waste liquors from metal finishing with iron content from a low of 0.5% to a high of 15%. Chemical–biological treatment combines chemical precipitation of phosphorus with biological removal of organic matter. Alum or iron salts are added prior to primary clarification, directly to the biological process, or prior to final clarification. For all application points, the amount of chemical added is about the same to achieve a specific phosphorus removal. Addition of coagulants to the primary clarifier enhances both suspended solids and BOD removal, resulting in 75% solids and 50% BOD removal.

The current paradigm is shifting design by taking WW as resources. For example, Anaerobic processes can be used to generate methane for energy production, nutrients can be recovered through struvite precipitation, and reclaimed water can be used for irrigation. In terms of per capita, 13 and 2.1 g N and P will be produced, which will result in 36 and 5.8 g N and P/m3/capita/day, respectively. Although more than 80 and 50% of N and P are contributed to by human urine to the WW flow, urine itself only contributes 1% of the WW flow rate of 0.35 m3. Therefore, for successful recovery of N and P, it is critical to separate urine from feces. Nutrients could be then be subsequently recovered through struvite precipitation, which is the most effective and easiest way to recover N and P from WW.

Diagram with arrow (secondary effluent) directing to a box labeled NH2+02→NO3- and proceeds to a circle labeled final settling. The arrow exits as nitrified effluent. In final settling, an arrow goes back to the box.

Figure 10.2 Flow diagram for nitrification by suspended growth aeration following conventional biological treatment.

10.3 Phosphorus Recovery

Phosphorus can be recovered from either sewage sludge or sludge liquor of a wastewater treatment plant (WWTP). Since cost and benefit are the major concerns in decision making, LCA and LCCBA are good methods to assess the sustainability of different technologies in terms of process design, operational conditions, and the type of phosphorus product. Up to 90% of the phosphorus entering the WWTP becomes sewage sludge (Pinnekamp et al., 2013), so the recovery of phosphorus from the sewage sludge line offers a higher potential of phosphorus recovery in comparison with a recovery process from the effluent of the WWTP. Almost all processes developed for phosphorus recovery focus on this fraction of the phosphorus originally contained in the raw WW. Elimination of dissolved phosphate from WW and the transformation to sewage sludge take place partly through bacterial growth (38–45%). The phosphorus is used by the microorganisms in the AS as nutrient and included in the biomass. Tertiary WWTPs additionally remove around 30–52% of the phosphorus from WW into the solid sludge phase. There are two main concepts for phosphorus elimination: (i) Enhanced biological phosphorus removal (EBPR) through phosphorus‐accumulating bacteria. Under specific process conditions, these bacteria are able to store large amounts of phosphorus. Under anaerobic conditions and in the presence of easily degradable organic compounds, the bacteria can use stored phosphorus as an energy source. Under aerobic conditions, the bacteria fill up the phosphorus storage again. The difference between the phosphorus uptake and the phosphorus released is referred as the net elimination in the form of polyphosphates (Seviour et al., 2003; Oehmen et al., 2007; Pinnekamp et al., 2007). (ii) Chemical phosphorus elimination applies aluminum, iron, or calcium salts. The phosphorus is removed as precipitation product of inorganic phosphates such as strengite, variscite, or apatite, respectively. As a result, larger amounts of sewage sludge are produced by the EBPR than WWTPs.

10.3.1 Enhanced Phosphorus Uptake

Some bacteria have the ability to accumulate phosphorus in the form of polyphosphates in excess of the phosphorus requirements by their growth. Conventional AS biomass typically contains 1–2% phosphorus on a dry weight basis, whereas biomass in an enhanced phosphate removal process is capable of accumulating phosphorus in excess of 3%; in some cases phosphorus contents up to 18% have been obtained with artificial, tailored substrates (Appeldoorn et al., 1992). The highest phosphorus concentration found in the biomass with domestic sewage as a substrate is about 7%. The essential features of the process are an anaerobic phase followed by an aerobic phase. Microorganisms are responsible for the phenomenon, but chemical precipitation of phosphorus may be a significant factor (Bark et al., 1992). The most commonly implicated species are from the genus Acinetobacter, but other related species may be involved. Operation of the process with anaerobic–aerobic sequencing provides favorable conditions for enrichment of the sludge with bio‐P microorganisms. In the presence of short‐chain fatty acids under aerobic conditions, the bio‐P microorganisms are able to store polyphosphates as a phosphorus source for energy generation. The initial anaerobic phase is required to produce short‐chain acids. Phosphorus is released from the sludge during the anaerobic phase, but the released phosphorus is taken up later in the process. These acids are utilized by the bio‐P microorganisms with concomitant phosphorus removal in an aerobic reactor. The phosphorus‐rich sludge formed is settled and removed from the WW. AS that has aerobically accumulated phosphorus in an enhanced phosphorus uptake system will release phosphate when an oxygen deficiency occurs (Schön et al., 1993). Rasmussen et al. (1994) found that most of the release was accomplished in the short time of 4 h under anaerobic conditions. Designing clarifiers to minimize the residence time of the sludge biomass is essential for the proper operation of an enhanced phosphorus removal process.

10.3.2 Struvite Precipitation

Struvite crystallization is an important mineral phosphorus recycling product. If P is not recovered, struvite could also spontaneously precipitate within pipes, pumps, or centrifuges, and cause severe operational problems in sludge handling and treatment. Due to the degradation of the biomass, an important part of the phosphorus is remobilized as orthophosphate and therefore dissolved in the liquid phase of the sludge water typically with concentrations in the range of 80–300 mg/l and NH4–N/L in the concentration range of 600–800 mg (Lahav et al., 2013). If magnesium is present and the pH is high enough (optimum above pH 8), struvite (MgNH4PO4∙6H2O) precipitates according to the following reversible reaction:

(10.6)images

The chemical balance is mainly influenced by stoichiometry (concentration) and matrix conditions (pH, temperature). A concentration of ortho‐PO4 above 50 mg/l and pH around 7.8–8.5 is the optimal conditions for struvite crystallization in the presence of sufficient magnesium and ammonia. The first step in crystallization is the nucleation, which forms the initial, smallest size crystals. The second step is the crystal growth, which is the mass transport of ions from the solution to the crystal surface and the incorporation of material into the crystal lattice. To produce fertilizer products, the kinetics of nucleation and growth are mainly determined by the supersaturation of the liquid phase in struvite, the pH, and the temperature. Oversaturation of struvite is defined as a state in which the solubility product is increased, which means that the product of the activities of phosphate, ammonium, and magnesium increases a certain value depending on temperature and ion strength. The pH influences the oversaturation indirectly by the concentrations of NH4+ and PO43− with an optimal pH leading to the highest oversaturation. The optimal pH lies in the range of pH 8–10.7. Britton et al. (2005) determined the conditional solubility pPS (product of magnesium, ammonium, and phosphate concentration) as a function of the pH: pPS = −0.203 pH2 + 4.09pH – 11.76. As a consequence of struvite crystallization, proton is released and the pH is required to be kept stable during the crystallization process. Crossing the limit of the metastable region will result in a sudden increase of crystallization rate. Furthermore, the degree of oversaturation influences the growth rate of different crystal sizes. For higher supersaturation, smaller crystals grow faster than large ones because of diffusion mechanisms.

Solubility product of struvite, Ks, is defined as follows:

images

Struvite would precipitate according to following reaction:

images

pH determines the species of ammonia between NH4+ and NH3 according to the following equilibrium reaction:

images

The equilibrium constant, Ka, is as follows:

images

Table 10.3 Composition of wastewater.

Parameter Concentration in water (mg/l)
NH4+ 1400
Mg2+ 21.4
PO43− 24
Ca2+ 21.2
K+ 2150
COD 3240
pH 7.9
Schematic displaying a box labeled waste water (200 mL). Three sides of the box (top, bottom, and left) have inward arrows with labels. The right side has two outward arrows labeled supernatant and 0.00339 kg MAP.

Figure 10.3 Purification and mass balances of struvite recovery in two‐step process.

Table 10.4 pH and ammonia lost to air.

pH NH4+ (mg/l) Ammonia lost to air (%)
7.9 1354 —
8.5 1205 11
9.0 1112 17.9

Table 10.5 The market prices of the chemicals in struvite precipitation.

Chemical Price ($/kg)
H3PO4 (75%) 0.40
MgCl2∙6H2O 0.31
MgO (85%) 0.44
NaOH (100%) 0.12
NH4+ 0.23

Table 10.6 Cost of NH4+–N.

Unit cost ($/kg NH4+–N) Authors
7.5–8.0 Çelen and Türker (2001)
9.1–11.38 Siegrist (1996)
4.55–9.92 Andrade and Schuiling (1999)
14.9 Webb et al. (1995)

10.4 Capital and Operation Cost of Reclaiming Water for Reuse

The most valuable product to be recovered is the treated water due to huge volume of treated WW effluent. However, distribution infrastructure is required for irrigation or recharge of groundwater aquifer. To reduce pipeline for distribution of water reuse, clusters of WRRFs close to decentralized WWTPs are ideal to proximate reused water to its intended customers. In Miami‐Dade County, for example, 300 MGD of treated WW could be reclaimed for irrigation, cooling, and agricultural irrigation. If the reclamation rates are 20, 40, and 60%, the Miami‐Dade Water and Sewer Department (WASD) could increase its annual revenue to $65.7, 131, and 197 million/year, respectively, at a water price of $3/1000 gal. In reality, the actual charge for water is about $10/1000 gal due to the WW fee associated with water consumption. Miami‐Dade WASD reclaims less than 7%. Therefore, there is great potential for Miami‐Dade WASD to enhance its financial balance sheet through water reuse. The major barrier for Miami‐Dade WASD is the capital investment for reclaiming the treated WW and building the infrastructure to reuse the water. Not far from Miami, Tampa sets up an exemplary model for cities over the world to follow. In 1995, the US EPA awarded Tampa–St. Petersburg $29.9 million for water reuse. Tampa has 2.5 million people, consumes 60 MGD, and had its share of $19.2 million dollars to build its water reclaim plant. Now, Tampa is able to provide an estimated 16 MGD of drinking water supply to the region through exchange of reclaimed water downstream for upstream surface water. It offsets potable water demands with reclaimed water usage for irrigation and other purposes. The water reclaim plant also benefits greatly from minimum environmental flows and the natural ecosystem in the Tampa Bay area. With additional financial support from the South Florida Water Management District (SWFWMD), Tampa is developing the South Tampa Area Reuse (STAR) project to provide reclaimed water for residents in the South Tampa area. In about 10 years, maximum STAR demand will be about 9 MGD in the dry season. The STAR project will recover about 10 MGD.

Due to economy of scale, unit capital and O&M costs of reclaiming water facility decreases with flow. To facilitate SEE design of water reclaiming plants, regression equations were developed using MatLab. These correlation equations can be used to estimate treatment project capital and O&M costs that can be estimated at different flow rates according to a California study (WateReuse Foundation, 2009). The regression equations use capital or O&M costs at 0.5 MGD as the reference cost. Dimensionless cost ratios between the cost at a specific flow rate and the corresponding cost at 0.5 MGD are plotted against the flow rate ratios. Most equations show that the unit capital and O&M cost decrease with flow rate exponentially before 10 MGD. When flow rate is greater than 10 MGD, the economy‐of‐scale effect decreases to a linear relationship.

10.4.1 Building

Table 10.7 Admin/lab/shop building.

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 0 0 0 0 0 0 0
Excavation and backfill (10%) 0 0 0 0 0 0 0
Miscellaneous metals (4%) 0 0 0 0 0 0 0
Yard piping (7%) 0 0 0 0 0 0 0
Total concrete 0 0 0 0 0 0 0
Equipment 0 0 0 0 0 0 0
Tax and delivery (11%) 0 0 0 0 0 0 0
Installation (20%) 0 0 0 0 0 0 0
Manufacturer services (4%) 0 0 0 0 0 0 0
Total mechanical 0 0 0 0 0 0 0
Protective coating (7%) 0 0 0 0 0 0 0
Electricity (10%) 0 0 0 0 0 0 0
Instrumentation (10%) 0 0 0 0 0 0 0
Housinga 600 000 600 000 750 000 1 800 000 3 000 000 3 600 000 4 200 000
Subtotal 600 000 600 000 750 000 1 800 000 3 000 000 3 600 000 4 200 000
Contractor overhead and profit (15%) 90 000 90 000 112 500 270 000 450 000 540 000 630 000
Scope‐of‐project contingency (30%) 180 000 180 000 225 000 540 000 900 000 1 080 000 1 260 000
Total construction cost 870 000 870 000 1 087 500 2 610 000 4 350 000 5 220 000 6 090 000
Engineering design (10%) 87 000 87 000 108 750 261 000 435 000 522 000 609 000
Total capital cost 957 000 957 000 1 196 250 2 871 000 4 785 000 5 742 000 6 699 000
Cost per gal ($) 1.91 0.96 0.60 0.57 0.48 0.38 0.33
O&M (5% construction cost) 43 500 43 500 54 375 130 500 217 500 261 000 304 500

a Based on an assumed $300/ft2 used for planning‐level estimates:

  1. Calculate unit capital and O&M costs.
  2. Plot unit cost/unit cost0 versus Q/ Q0 .
  3. Determine correlation equations between unit cost/unit cost0 for capital and O&M versus Q/Q0, respectively.

Table 10.8 Unit capital cost and unit operation and maintenance cost of admin/lab/shop building at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 1914.00 0.2384
1 957.00 0.1192
2 598.13 0.0745
5 574.20 0.0715
10 478.50 0.0596
15 382.80 0.0477
20 334.95 0.0417

Table 10.9 Unit cost ratio of admin/lab/shop building at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.5000 0.5000
4 0.3125 0.3125
10 0.3000 0.3000
20 0.2500 0.2500
30 0.2000 0.2000
40 0.1750 0.1750
Unit cost/unit cost0 vs. Q/Q0 for admin/lab/shop building displaying a descending solid line representing power trendline connected to a descending dashed line representing linear trendline.

Figure 10.4 Unit capital cost/unit capital cost0 versus Q/Q0 for admin/lab/shop building, unit capital cost0 = 1914.00$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for admin/lab/shop building displaying a descending solid line representing power trendline connected to a descending dashed line representing linear trendline.

Figure 10.5 Unit O&M cost/unit O&M cost0 versus Q/Q0 for admin/lab/shop building, unit O&M cost0 = 0.2384$/kgal, Q0 = 0.5 MGD.

10.4.2 Headwork

Table 10.10 Headworks.

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concretea 6 400 7 200 11 200 20 000 24 800 29 600 29 600
Excavation and backfill (10%) 640 720 1 120 2 000 2 480 2 960 2 960
Miscellaneous metals (4%) 256 288 448 800 992 1 184 1 184
Yard piping (7%) 448 504 784 1 400 1 736 2 072 2 072
Total concrete 7 744 8 712 13 552 24 200 30 008 35 816 35 816
Equipmentb,c 167 500 197 000 206 500 349 000 545 000 695 000 835 000
Tax and delivery (11%) 18 425 21 670 22 715 38 390 59 950 76 450 91 850
Installation (20%) 33 500 39 400 41 300 69 800 109 000 139 000 167 000
Manufacturer services (4%) 6 700 7 880 8 260 13 960 21 800 27 800 33 400
Total mechanical 226 125 265 950 278 775 471 150 735 750 938 250 1 127 250
Protective coating (7%) 16 371 19 226 20 463 34 675 53 603 68 185 81 415
Electricity (10%) 23 387 27 466 29 233 49 535 76 576 97 407 116 307
Instrumentation (10%) 23 387 27 466 29 233 49 535 76 576 97 407 116 307
Housing 0 0 0 0 0 0 0
Subtotal 297 014 348 821 371 255 629 095 972 513 1 237 064 1 477 094
Contractor overhead and profit (15%) 44 552 52 323 55 688 94 364 145 877 185 560 221 564
Scope‐of‐project contingency (30%) 89 104 104 646 111 377 188 728 291 754 371 119 443 128
Total construction cost 430 670 505 790 538 320 912 187 1 410 143 1 793 743 2 141 786
Engineering design (10%) 43 067 50 579 53 832 91 219 141 014 179 374 214 179
Total capital cost 473 737 556 369 592 152 1 003 406 1 551 158 1 973 117 2 355 965
Cost per gal ($) 0.95 0.56 0.30 0.20 0.16 0.13 0.12
O&M (5% construction cost) 21 533 25 290 26 916 45 609 70 507 89 687 107 089

a Concrete was sized for grit chambers only.

b Equipment costs include both screens and Pista Grit.

c For screens, the average cost of 6‐mm and 2‐mm screens is used.

Table 10.11 Unit capital cost and unit operation and maintenance cost of headworks at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 947.47 0.1180
1 556.37 0.0693
2 296.08 0.0369
5 200.68 0.0250
10 155.12 0.0193
15 131.54 0.0164
20 117.80 0.0147

Table 10.12 Unit cost ratio of headworks at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.5872 0.5872
4 0.3125 0.3125
10 0.2118 0.2118
20 0.1637 0.1637
30 0.1388 0.1388
40 0.1243 0.1243
Unit cost/unit cost0 vs. Q/Q0 for headworks displaying a descending solid curve with 6 dots, where unit capital cost0 = 947.47$/kgal and Q0 = 0.5 MGD.

Figure 10.6 Unit capital cost/unit capital cost0 versus Q/Q0 for headworks, unit capital cost0 = 947.47$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for headworks displaying a descending solid curve with 6 dots, where unit O&M cost0 = 0.1180$/kgal and Q0 = 0.5 MGD.

Figure 10.7 Unit O&M cost/unit O&M cost0 versus Q/Q0 for headworks, unit O&M cost0 = 0.1180$/kgal, Q0 = 0.5 MGD.

10.4.3 Oxidation

Table 10.13 Ox (CA Title 22).

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concretea 774 400 1 024 000 1 861 600 3 640 000 7 156 000 11 017 600 16 400 800
Excavation and backfill (10%) 77 440 102 400 186 160 364 000 715 600 1 101 760 1 640 080
Miscellaneous metals (4%) 30 976 40 960 74 464 145 600 286 240 440 704 656 032
Yard piping (7%) 54 208 71 680 130 312 254 800 500 920 771 232 1 148 056
Total concrete 937 024 1 239 040 2 252 536 4 404 400 8 658 760 13 331 296 19 844 968
Equipmentb,c 548 000 598 000 676 000 900 000 1 800 000 2 580 000 3 360 000
Tax and delivery (11%) 60 280 65 780 74 360 99 000 198 000 283 800 369 600
Installation (20%) 109 600 119 600 135 200 180 000 360 000 516 000 672 000
Manufacturer services (4%) 21 920 23 920 27 040 36 000 72 000 103 200 134 400
Total mechanical 739 800 807 300 912 600 1 215 000 2 430 000 3 483 000 4 536 000
Protective coating (7%) 117 378 143 244 221 560 393 358 776 213 1 177 001 1 706 668
Electricity (10%) 167 682 204 634 316 514 561 940 1 108 876 1 681 430 2 438 097
Instrumentation (10%) 167 682 204 634 316 514 561 940 1 108 876 1 681 430 2 438 097
Housing 0 0 0 0 0 0 0
Subtotal 2 129 566 2 598 852 4 019 723 7 136 638 14 082 725 21 354 156 30 963 829
Contractor overhead and profit (15%) 319 435 389 828 602 958 1 070 496 2 112 409 3 203 123 4 644 574
Scope‐of‐project contingency (30%) 638 870 779 656 1 205 917 2 140 991 4 224 818 6 406 247 9 289 149
Total construction cost 3 087 871 3 768 335 5 828 598 10 348 125 20 419 952 30 963 526 44 897 553
Engineering design (10%) 308 787 376 834 582 860 1 034 813 2 041 995 3 096 353 4 489 755
Total capital cost 3 396 659 4 145 169 6 411 458 11 382 938 22 461 947 34 059 879 49 387 308
Cost per gal ($) 6.79 4.15 3.21 2.28 2.25 2.27 2.47
O&M (5% construction cost) 154 394 188 417 291 430 517 406 1 020 998 1 548 176 2 244 878

a Concrete cost is only for grit chambers.

b Equipment costs include both screens and Pista Grit (Western Environmental Equipment Co. and Siemens Technologies).

c For screens, the average cost of 6‐mm and 2‐mm screens was used.

Table 10.14 Unit capital cost and unit operation and maintenance cost of Ox (CA Title 22) at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 6793.32 0.8460
1 4145.17 0.5162
2 3205.73 0.3992
5 2276.59 0.2835
10 2246.19 0.2797
15 2270.66 0.2828
20 2469.37 0.3075

Table 10.15 Unit cost ratio of Ox (CA Title 22) at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.6102 0.6102
4 0.4719 0.4719
10 0.3351 0.3351
20 0.3306 0.3306
30 0.3342 0.3342
40 0.3635 0.3635
Unit capital cost/unit capital cost0 vs. Q/Q0 for Ox displaying descending solid and dashed lines representing power trendline and linear trendline, respectively, where unit capital cost0 = 6793.32$/kgal.

Figure 10.8 Unit capital cost/unit capital cost0 versus Q/Q0 for Ox (CA Title 22), unit capital cost0 = 6793.32$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for Ox displaying descending solid and dashed lines representing power trendline and linear trendline, respectively, where unit O&M cost0 = 0.8460$/kgal.

Figure 10.9 Unit O&M cost/unit O&M cost0 versus Q/Q0 for Ox (CA Title 22), unit O&M cost0 = 0.8460$/kgal, Q0 = 0.5 MGD.

10.4.4 Aerobic SBR

Table 10.16 Aqua Aerobics SBR (CA Title 22).

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 856 000 1 524 800 1 680 000 2 872 800 3 537 600 4 330 400 5 434 400
Excavation and backfill (10%) 85 600 152 480 168 000 287 280 353 760 433 040 543 440
Miscellaneous metals (4%) 34 240 60 992 67 200 114 912 141 504 173 216 217 376
Yard piping (7%) 59 920 106 736 117 600 201 096 247 632 303 128 380 408
Total concrete 1 035 760 1 845 008 2 032 800 3 476 088 4 280 496 5 239 784 6 575 624
Equipmenta 500 000 625 000 875 000 1 400 000 1 900 000 2 400 000 2 650 000
Tax and delivery (11%) 55 000 68 750 96 250 154 000 209 000 264 000 291 500
Installation (20%) 100 000 125 000 175 000 280 000 380 000 480 000 530 000
Manufacturer services (4%) 20 000 25 000 35 000 56 000 76 000 96 000 106 000
Total mechanical 675 000 843 750 1 181 250 1 890 000 2 565 000 3 240 000 3 577 500
Protective coating (7%) 119 753 188 213 224 984 375 626 479 185 593 585 710 719
Electricity (10%) 171 076 268 876 321 405 536 609 684 550 847 978 1 015 312
Instrumentation (10%) 171 076 268 876 321 405 536 609 684 550 847 978 1 015 312
Housing 0 0 0 0 0 0 0
Subtotal 2 172 665 3 414 723 4 081 844 6 814 932 8 693 780 10 769 326 12 894 467
Contractor overhead and profit (15%) 325 900 512 208 612 277 1 022 240 1 304 067 1 615 399 1 934 170
Scope‐of‐project contingency (30%) 651 800 1 024 417 1 224 553 2 044 480 2 608 134 3 230 798 3 868 340
Total construction cost 3 150 365 4 951 348 5 918 673 9 881 651 12 605 981 15 615 522 18 696 978
Engineering design (10%) 315 036 495 135 591 867 988 165 1 260 598 1 561 552 1 869 698
Total capital cost 3 465 401 5 446 483 6 510 540 10 869 816 13 866 579 17 177 074 20 566 676
Cost per gal ($) 6.93 5.45 3.26 2.17 1.39 1.15 1.03
O&M (5% construction cost) 157 518 247 567 295 934 494 083 630 299 780 776 934 849

a Equipment costs provided by Aqua Aerobics.

Table 10.17 Unit capital cost and unit operation and maintenance cost of Aqua Aerobics SBR (CA Title 22) at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 6930.80 0.8631
1 5446.48 0.6783
2 3255.27 0.4054
5 2173.96 0.2707
10 1386.66 0.1727
15 1145.14 0.1426
20 1028.33 0.1281

Table 10.18 Unit cost ratio of Aqua Aerobics SBR (CA Title 22) at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.7858 0.7858
4 0.4697 0.4697
10 0.3137 0.3137
20 0.2001 0.2001
30 0.1652 0.1652
40 0.1484 0.1484
Unit capital cost/unit capital cost0 vs. Q/Q0 for Aqua Aerobics SBR displaying 7 dots along a descending curve, where unit capital cost0 = 6930.80$/kgal and Q0 = 0.5 MGD.

Figure 10.10 Unit capital cost/unit capital cost0 versus Q/Q0 for Aqua Aerobics SBR (CA Title 22), unit capital cost0 = 6930.80$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for Aqua Aerobics SBR displaying 7 dots along a descending curve, where unit O&M cost0 = 0.8631$/kgal and Q0 = 0.5 MGD.

Figure 10.11 Unit O&M cost/unit O&M cost0 versus Q/Q0 for Aqua Aerobics SBR (CA Title 22), unit O&M cost0 = 0.8631$/kgal, Q0 = 0.5 MGD.

10.4.5 MBR

Table 10.19 Aqua Aerobics MBR (CA Title 22).

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 610 400 1 062 400 2 012 000 4 722 400 9 684 800 13 448 800 19 054 400
Excavation and backfill (10%) 61 040 106 240 201 200 472 240 968 480 1 344 880 1 905 440
Miscellaneous metals (4%) 24 416 42 496 80 480 188 896 387 392 537 952 762 176
Yard piping (7%) 42 728 74 368 140 840 330 568 677 936 941 416 1 333 808
Total concrete 738 584 1 285 504 2 434 520 5 714 104 11 718 608 16 273 048 23 055 824
Equipmenta 1 000 000 2 000 000 2 900 000 8 000 000 14 500 000 20 500 000 26 000 000
Tax and delivery (11%) 110 000 220 000 319 000 880 000 1 595 000 2 255 000 2 860 000
Installation (20%) 200 000 400 000 580 000 1 600 000 2 900 000 4 100 000 5 200 000
Manufacturer services (4%) 40 000 80 000 116 000 320 000 580 000 820 000 1 040 000
Total mechanical 1 350 000 2 700 000 3 915 000 10 800 000 19 575 000 27 675 000 35 100 000
Protective coating (7%) 146 201 278 985 444 466 1 155 987 2 190 553 3 076 363 4 070 908
Electricity (10%) 208 858 398 550 634 952 1 651 410 3 129 361 4 394 805 5 815 582
Instrumentation (10%) 208 858 398 550 634 952 1 651 410 3 129 361 4 394 805 5 815 582
Housing 0 0 0 0 0 0 0
Subtotal 2 652 502 5 061 590 8 063 890 20 972 912 39 742 882 55 814 021 73 857 896
Contractor overhead and profit (15%) 397 875 759 239 1 209 584 3 145 937 5 961 432 8 372 103 11 078 684
Scope‐of‐project contingency (30%) 795 751 1 518 477 2 419 167 6 291 874 11 922 865 16 744 206 22 157 369
Total construction cost 3 846 127 7 339 306 11 692 641 30 410 723 57 627 179 80 930 330 107 093 950
Engineering design (10%) 384 613 733 931 1 169 264 3 041 072 5 762 718 8 093 033 10 709 395
Total capital cost 4 230 740 8 073 236 12 861 905 33 451 795 63 389 897 89 023 363 117 803 345
Cost per gal ($) 8.46 8.07 6.43 6.69 6.34 5.93 5.89
O&M (5% construction cost) 192 306 366 965 584 632 1 520 536 2 881 359 4 046 517 5 354 697

a Equipment costs provided by Aqua Aerobics.

Table 10.20 Unit capital cost and unit operation and maintenance cost of Aqua Aerobics MBR (CA Title 22) at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 8461.48 1.0537
1 8073.24 1.0054
2 6430.95 0.8009
5 6690.36 0.8332
10 6338.99 0.7894
15 5934.89 0.7391
20 5890.17 0.7335

Table 10.21 Unit cost ratio of Aqua Aerobics MBR (CA Title 22) at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.9541 0.9541
4 0.7600 0.7600
10 0.7907 0.7907
20 0.7492 0.7492
30 0.7014 0.7014
40 0.6961 0.6961
Unit capital cost/unit capital cost0 vs. Q/Q0 for Aqua Aerobics MBR displaying a descending solid line (power trend line) linked to a descending dashed line (linear trendline), with 7 dots.

Figure 10.12 Unit capital cost/unit capital cost0 versus Q/Q0 for Aqua Aerobics MBR (CA Title 22), unit capital cost0 = 8461.48 $/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for Aqua Aerobics MBR displaying a descending solid line (power trend line) linked to a descending dashed line (linear trendline), with 7 dots.

Figure 10.13 Unit O&M cost/unit O&M cost0 versus Q/Q0 for Aqua Aerobics MBR (CA Title 22), unit O&M cost0 = 1.0537$/kgal, Q0 = 0.5 MGD.

10.4.6 Microfiltration

Table 10.22 Annual cost of microfiltration.

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 0 0 0 0 0 0 0
Excavation and backfill (10%) 0 0 0 0 0 0 0
Miscellaneous metals (4%) 0 0 0 0 0 0 0
Yard piping (7%) 0 0 0 0 0 0 0
Total concrete 0 0 0 0 0 0 0
Equipment 1 079 369 1 641 697 2 496 986 4 346 802 6 611 393 8 449 445 10 055 789
Tax and delivery (11%) 118 731 180 587 274 668 478 148 727 253 929 439 1 106 137
Installation (20%) 215 874 328 339 499 397 869 360 1 322 279 1 689 889 2 011 158
Manufacturer services (4%) 43 175 65 668 99 879 173 872 264 456 337 978 402 232
Total mechanical 1 457 148 2 216 291 3 370 931 5 868 183 8 925 381 11 406 751 13 575 315
Protective coating (7%) 102 000 155 140 235 965 410 773 624 777 798 473 950 272
Electricity (10%) 145 715 221 629 337 093 586 818 892 538 1 140 675 1 357 532
Instrumentation (10%) 145 715 221 629 337 093 586 818 892 538 1 140 675 1 357 532
Housinga 175 000 350 000 700 000 1 750 000 3 500 000 5 250 000 7 000 000
Subtotal 2 025 578 3 164 690 4 981 082 9 202 592 14 835 233 19 736 573 24 240 650
Contractor overhead and profit (15%) 303 837 474 703 747 162 1 380 389 2 225 285 2 960 486 3 636 098
Scope‐of‐project contingency (30%) 607 673 949 407 1 494 325 2 760 778 4 450 570 5 920 972 7 272 195
Total construction cost 2 937 088 4 588 800 7 222 570 13 343 758 21 511 088 28 618 032 35 148 943
Engineering design (10%) 293 709 458 880 722 257 1 334 376 2 151 109 2 861 803 3 514 894
Total capital cost 3 230 797 5 047 680 7 944 827 14 678 134 23 662 197 31 479 835 38 663 837
Cost per gal ($) 6.46 5.05 3.97 2.94 2.37 2.10 1.93
O&M (5% construction cost) 146 854 229 440 361 128 667 188 1 075 554 1 430 902 1 757 447

a Housing footprint based on general, unpublished rules of thumb. Assumed $250/ft2.

Table 10.23 Unit capital cost and unit operation and maintenance cost of MF at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 6461.59 0.8047
1 5047.68 0.6286
2 3972.41 0.4947
5 2935.63 0.3656
10 2366.22 0.2947
15 2098.66 0.2614
20 1933.19 0.2407

Table 10.24 Unit cost ratio of MF at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.7812 0.7812
4 0.6148 0.6148
10 0.4543 0.4543
20 0.3662 0.3662
30 0.3248 0.3248
40 0.2992 0.2992
Unit capital cost/unit capital cost0 vs. Q/Q0 for MF displaying 7 dots along a descending curve, where unit capital cost0 = 6461.59$/kgal and Q0 = 0.5 MGD.

Figure 10.14 Unit capital cost/unit capital cost0 versus Q/Q0 for MF, unit capital cost0 = 6461.59$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for MF displaying 7 dots along a descending curve, where unit O&M cost0 = 0.8047$/kgal and Q0 = 0.5 MGD.

Figure 10.15 Unit O&M cost/unit O&M cost0 versus Q/Q0 for MF, unit O&M cost0 = 0.8047$/kgal, Q0 = 0.5 MGD.

10.4.7 Reverse Osmosis

Table 10.25 Annual cost of reverse osmosis.

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 0 0 0 0 0 0 0
Excavation and backfill (10%) 0 0 0 0 0 0 0
Miscellaneous metals (4%) 0 0 0 0 0 0 0
Yard piping (7%) 0 0 0 0 0 0 0
Total concrete 0 0 0 0 0 0 0
Equipment 770 000 1 110 000 1 610 000 2 610 000 3 780 000 4 680 000 5 450 000
Tax and delivery (11%) 84 700 122 100 177 100 287 100 415 800 514 800 599 500
Installation (20%) 154 000 222 000 322 000 522 000 756 000 936 000 1 090 000
Manufacturer services (4%) 30 800 44 400 64 400 104 400 151 200 187 200 218 000
Total mechanical 1 039 500 1 498 500 2 173 500 3 523 500 5 103 000 6 318 000 7 357 500
Protective coating (7%) 72 765 104 895 152 145 246 645 357 210 442 260 515 025
Electricity (10%) 103 950 149 850 217 350 352 350 510 300 631 800 735 750
Instrumentation (10%) 103 950 149 850 217 350 352 350 510 300 631 800 735 750
Housinga 210 000 420 000 840 000 2 100 000 4 200 000 6 300 000 8 400 000
Subtotal 1 530 165 2 323 095 3 600 345 6 574 845 10 680 810 14 323 860 17 744 025
Contractor overhead and profit (15%) 229 525 348 464 540 052 986 227 1 602 122 2 148 579 2 661 604
Scope‐of‐project contingency (30%) 459 050 696 929 1 080 104 1 972 454 3 204 243 4 297 158 5 323 208
Total construction cost 2 218 739 3 368 488 5 220 500 9 533 525 15 487 175 20 769 597 25 728 836
Engineering design (10%) 221 874 336 849 522 050 953 353 1 548 717 2 076 960 2 572 884
Total capital cost 2 440 613 3 705 337 5 742 550 10 486 878 17 035 892 22 846 557 28 301 720
Cost per gal ($) 4.88 3.71 2.87 2.10 1.70 1.52 1.42
O&M (5% construction cost) 110 937 168 424 261 025 476 676 774 359 1 038 480 1 286 442

a Housing footprint based on general, unpublished rules of thumb. Assumed $250/ft2.

Table 10.26 Unit capital cost and unit operation and maintenance cost of RO at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 4881.23 0.6079
1 3705.34 0.4614
2 2871.28 0.3576
5 2097.38 0.2612
10 1703.59 0.2122
15 1523.10 0.1897
20 1415.09 0.1762

Table 10.27 Unit cost ratio of RO at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.7591 0.7591
4 0.5882 0.5882
10 0.4297 0.4297
20 0.3490 0.3490
30 0.3120 0.3120
40 0.2899 0.2899
Unit capital cost/unit capital cost0 vs. Q/Q0 for RO displaying 7 dots along a descending curve, where unit capital cost0 = 4881.23$/kgal and Q0 = 0.5 MGD.

Figure 10.16 Unit capital cost/unit capital cost0 versus Q/Q0 for RO, unit capital cost0 = 4881.23$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for RO displaying 7 dots along a descending curve, where unit O&M cost0 = 0.6079$/kgal and Q0 = 0.5 MGD.

Figure 10.17 Unit O&M cost/unit O&M cost0 versus Q/Q0 for RO, unit O&M cost0 = 0.6079$/kgal, Q0 = 0.5 MGD.

10.4.8 Filtration

Table 10.28 Filtration.

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 88 800 120 376 171 406 282 643 466 206 558 743 743 428
Excavation and backfill (10%) 8 880 12 038 17 141 28 264 46 621 55 874 74 343
Miscellaneous metals (4%) 3 552 4 815 6 856 11 306 18 648 22 350 29 737
Yard piping (7%) 6 216 8 426 11 998 19 785 32 634 39 112 52 040
Total concrete 107 448 145 655 207 401 341 998 564 109 676 079 899 548
Equipmenta,b 181 303 193 498 214 085 263 876 394 212 431 061 565 437
Tax and delivery (11%) 19 943 21 285 23 549 29 026 43 363 47 417 62 198
Installation (20%) 36 261 38 700 42 817 52 775 78 842 86 212 113 087
Manufacturer services (4%) 7 252 7 740 8 563 10 555 15 768 17 242 22 617
Total mechanical 244 759 261 222 289 015 356 233 532 186 581 932 763 340
Protective coating (7%) 24 654 28 481 34 749 48 876 76 741 88 061 116 402
Electricity (10%) 35 221 40 688 49 642 69 823 109 630 125 801 166 289
Instrumentation (10%) 35 221 40 688 49 642 69 823 109 630 125 801 166 289
Housing 0 0 0 0 0 0 0
Subtotal 447 303 516 734 630 448 886 753 1 392 295 1 597 674 2 111 868
Contractor overhead and profit (15%) 67 095 77 510 94 567 133 013 208 844 239 651 316 780
Scope‐of‐project contingency (30%) 134 191 155 020 189 134 266 026 417 689 479 302 633 560
Total construction cost 648 589 749 264 914 150 1 285 792 2 018 828 2 316 628 3 062 208
Engineering design (10%) 64 859 74 926 91 415 128 579 201 883 231 663 306 221
Total capital cost 713 448 824 191 1 005 565 1 414 371 2 220 711 2 548 291 3 368 429
Cost per gal ($) 1.43 0.82 0.50 0.28 0.22 0.17 0.17
O&M (5% construction cost) 32 429 37 463 45 708 64 290 100 941 115 831 153 110

a Average cost used for filtration equipment [Ox and SBR for Title 22 (California) and Class A+ (Arizona) requirements].

b Cost of equipment includes the cost of fiberglass reinforced plastic (FRP) tanks and metering pump skid for alum and cationic polymer (Augusta Fiberglass budget).

Table 10.29 Unit capital cost and unit operation and maintenance cost of filtration at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 1426.90 0.1777
1 824.19 0.1026
2 502.78 0.0626
5 282.87 0.0352
10 222.07 0.0277
15 169.89 0.0212
20 168.42 0.0210

Table 10.30 Unit cost ratio of filtration at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.5776 0.5776
4 0.3524 0.3524
10 0.1982 0.1982
20 0.1556 0.1556
30 0.1191 0.1191
40 0.1180 0.1180
Unit capital cost/unit capital cost0 vs. Q/Q0 for filtration displaying 6 dots along a descending curve, where unit capital cost0 = 1426.90$/kgal and Q0 = 0.5 MGD.

Figure 10.18 Unit capital cost/unit capital cost0 versus Q/Q0 for filtration, unit capital cost0 = 1426.90$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for filtration displaying 6 dots along a descending curve, where unit O&M cost0 = 0.1777$/kgal and Q0 = 0.5 MGD.

Figure 10.19 Unit O&M cost/unit O&M cost0 versus Q/Q0 for filtration, unit O&M cost0 = 0.1777$/kgal, Q0 = 0.5 MGD.

10.4.9 Disinfection

Table 10.31 Disinfection (CA).

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concretea 119 872 227 916 295 200 491 674 772 030 856 583 955 531
Excavation and backfill (10%) 11 987 22 792 29 520 49 167 77 203 85 658 95 553
Miscellaneous metals (4%) 4 795 9 117 11 808 19 667 30 881 34 263 38 221
Yard piping (7%) 8 391 15 954 20 664 34 417 54 042 59 961 66 887
Total concrete 145 045 275 778 357 192 594 926 934 156 1 036 465 1 156 192
Equipmentb 14 979 15 682 17 034 19 887 23 126 28 347 44 118
Tax and delivery (11%) 1 648 1 725 1 874 2 188 2 544 3 118 4 853
Installation (20%) 2 996 3 136 3 407 3 977 4 625 5 669 8 824
Manufacturer services (4%) 599 627 681 795 925 1 134 1 765
Total mechanical 20 222 21 171 22 996 26 847 31 220 38 268 59 559
Protective coating (7%) 11 569 20 786 26 613 43 524 67 576 75 231 85 103
Electricity (10%) 16 527 29 695 38 019 62 177 96 538 107 473 121 575
Instrumentation (10%) 16 527 29 695 38 019 62 177 96 538 107 473 121 575
Housing 0 0 0 0 0 0 0
Subtotal 209 888 377 125 482 839 789 652 1 226 027 1 364 912 1 544 005
Contractor overhead and profit (15%) 31 483 56 569 72 426 118 448 183 904 204 737 231 601
Scope‐of‐project contingency (30%) 62 966 113 138 144 852 236 896 367 808 409 473 463 201
Total construction cost 304 338 546 832 700 116 1 144 995 1 777 740 1 979 122 2 238 807
Engineering design (10%) 30 434 54 683 70 012 114 500 177 774 197 912 223 881
Total capital cost 334 772 601 515 770 128 1 259 495 1 955 514 2 177 034 2 462 687
Cost per gal ($) 0.67 0.60 0.39 0.25 0.20 0.15 0.12
O&M (5% construction cost) 15 217 27 342 35 006 57 250 88 887 98 956 111 940

a Concrete cost is based on average contact time for Arizona and California SBR, Ox, and MBR.

b Equipment cost includes the cost of the chemical system in which only FRP tanks and metering pump skid system are estimated for (Augusta Fiberglass).

Table 10.32 Unit capital cost and unit operation and maintenance cost of disinfection at different flow rates.

Q (MGD) Unit capital cost ($/kgal) Unit O&M costs ($/kgal)
0.5 669.54 0.0834
1 601.52 0.0749
2 385.06 0.0480
5 251.90 0.0314
10 195.55 0.0244
15 145.14 0.0181
20 123.13 0.0153

Table 10.33 Unit cost ratio of disinfection at different flow ratios.

Q/Q0 Unit capital cost/unit capital cost0 Unit O&M costs/unit O&M costs0
1 1.0000 1.0000
2 0.8984 0.8984
4 0.5751 0.5751
10 0.3762 0.3762
20 0.2921 0.2921
30 0.2168 0.2168
40 0.1839 0.1839
Unit capital cost/unit capital cost0 vs. Q/Q0 for disinfection displaying 7 dots along a descending curve, where unit capital cost0 = 669.54$/kgal and Q0 = 0.5 MGD.

Figure 10.20 Unit capital cost/unit capital cost0 versus Q/Q0 for disinfection, unit capital cost0 = 669.54$/kgal, Q0 = 0.5 MGD.

Unit O&M cost/unit O&M cost0 vs. Q/Q0 for disinfection displaying 7 dots along a descending curve, where unit O&M cost0 = 0.0834$/kgal and Q0 = 0.5 MGD.

Figure 10.21 Unit O&M cost/unit O&M cost0 versus Q/Q0 for disinfection, unit O&M cost0 = 0.0834$/kgal, Q0 = 0.5 MGD.

10.5 Exercise

10.5.1 Questions

  1. What is the most valuable material in WWTP to be recovered?
  2. Please rank economic values of nutrient, energy, and water recovery.
  3. Water could be recovered in a large quantity, what prevents the reuse of the treated effluent from WWTPs?
  4. If nutrients such as N and P in the form of struvite are so valuable, why is nutrient recovery not commonly practiced in WWTPs?
  5. What are the common treatment processes for organic, toxic metals, and virus or bacteria to achieve wastewater quality standards?
  6. Which unit process is the most expensive in reclaiming treated wastewater?

10.5.2 Calculations

  1. Table 10.34 shows the capital cost and operation and maintenance (O&M) cost of Zenon MBR (CA Title 22) at different flow rates:
    1. Calculate unit capital and O&M costs.
    2. Plot unit cost/unit cost0 versus Q/Q0.
    3. Determine correlation equations between unit cost/unit cost0 for capital and O&M versus Q/Q0, respectively.
  2. A water utility in Southern Florida conducted feasibility study of reclaiming water for reuse. The treatment train of the pilot WRRF is to nitrify the secondary effluent from WWTP effluent using UF, RO, and UV disinfection. The target is to achieve total nitrogen < 1.5 mg/l, total phosphorus < 0.02 mg/l, BOD5 < 5 mg/l, and TSS < 5 mg/l. A pilot scale was tested with flow rate of 20 GPD. The influent has concentration of total nitrogen of 19.7 mg/l and total phosphorus of 2.2 mg/l, while the effluent has concentration of total nitrogen of 1.20 mg/l and total phosphorus of 0.007 mg/l. If the capital and O&M costs that were valid from the California tests were also applicable to Southern Florida, please answer the following if the WRRF is to be built to have a flow rate of 10 MGD:
    1. What would be the unit capital and O&M costs according to the equations present in this chapter?
    2. What would be the total capital? If the design life expectancy is 50 years, what would be the total O&M cost?
    3. If all the 10 MGD reclaimed water were sold for irrigation purpose at a price of $5/1000 gal, how many years the capital costs could be recovered after the WRRF is built and in operation?
    4. In your option, what would be the major factors that would affect your cost and benefit analysis of this project?

Table 10.34 Zenon MBR (CA Title 22).

Expense ($) Cost per amount of flow (MGD)
0.5 1.0 2.0 5.0 10 15 20
Concrete 610 400 1 062 400 2 012 000 4 722 400 9 684 800 13 448 800 19 054 400
Excavation and backfill (10%) 61 040 106 240 201 200 472 240 968 480 1 344 880 1 905 440
Miscellaneous metals (4%) 24 416 42 496 80 480 188 896 387 392 537 952 762 176
Yard piping (7%) 42 728 74 368 140 840 330 568 677 936 941 416 1 333 808
Total concrete 738 584 1 285 504 2 434 520 5 714 104 11 718 608 16 273 048 23 055 824
Equipmenta 2 963 000 3 704 000 7 037 000 14 815 000 24 306 000 27 778 000 29 630 000
Tax and delivery (11%) 325 930 407 440 774 070 1 629 650 2 673 660 3 055 580 3 259 300
Installation (20%) 592 600 740 800 1 407 400 2 963 000 4 861 200 5 555 600 5 926 000
Manufacturer services (4%) 118 520 148 160 281 480 592 600 972 240 1 111 120 1 185 200
Total mechanical 4 000 050 5 000 400 9 499 950 20 000 250 32 813 100 37 500 300 40 000 500
Protective coating (7%) 331 704 440 013 835 413 1 800 005 3 117 220 3 764 134 4 413 943
Electricity (10%) 473 863 628 590 1 193 447 2 571 435 4 453 171 5 377 335 6 305 632
Instrumentation (10%) 473 863 628 590 1 193 447 2 571 435 4 453 171 5 377 335 6 305 632
Housing 0 0 0 0 0 0 0
Subtotal 6 018 065 7 983 098 15 156 777 32 657 230 56 555 269 68 292 152 80 081 531
Contractor overhead and profit (15%) 902 710 1 197 465 2 273 517 4 898 584 8 483 290 10 243 823 12 012 230
Scope‐of‐project contingency (30%) 1 805 420 2 394 929 4 547 033 9 797 169 16 966 581 20 487 646 24 024 459
Total construction cost 8 726 195 11 575 492 21 977 327 47 352 983 82 005 140 99 023 620 116 118 221
Engineering design (10%) 872 619 1 157 549 2 197 733 4 735 298 8 200 514 9 902 362 11 611 822
Total capital cost 9 598 814 12 733 041 24 175 059 52 088 281 90 205 654 108 925 982 127 730 043
Cost per gal ($) 19.20 12.73 12.09 10.42 9.02 7.26 6.39
O&M (5% construction cost) 436 310 578 775 1 098 866 2 367 649 4 100 257 4 951 181 5 805 911

a Equipment costs provided by Zenon Technologies.

10.5.3 Projects

10.5.3.1 Xiongan Project

If the Xiongan is planned for populations of 1, 2, and 5 million in 5, 10, and 20 years, respectively, what percentage of wastewater should be reclaimed? Please design a system that could be applied to reclaim wastewater using the similar treatment train as in the previous problem to achieve the target percentage. Please use the capital and O&M cost diagram to estimate the capital and O&M costs for 50 years.

10.5.3.2 Community Proposal Project

Please make an appointment with officials in your hometown and collect waste reuse data. According to the data, please do the following:

  1. Calculate the percentage of water reuse rates.
  2. Determine whether the city is sustainable in terms of water resources.
  3. Please design a water reuse system so that the city becomes sustainable in terms of water resources.
  4. Please estimate the capital and O&M costs of your proposed project for 20 and 50 years.
  5. What is the return‐on‐investment period for the water reuse system?

References

  1. Andrade, A and Schuling, O. (1999). Literature search, digest and assessment concerning struvite recovery for recycling from waste waters. Final Report for CEEP (CEFIC). Holland: Geochem Research BV/Utrecht University Holland.
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