Chapter Nine
Policy and Management of Contaminated Construction and Demolition Waste
Abstract
Whole process management system for construction and demolition (C&D) waste including source prevention, identification and separation, disposal, and recycling has been established. The hazardous wastes among the industrial C&D waste should be separated on site prior to recycling. Acid-resistant brick and stone are recommended as the surface materials and the depth of which should be more than 30 mm for the main blocks in workshops. Meanwhile, resin and sodium silicate are applicable for the masonry materials. Explicit responsibilities among different departments such as the Environmental Protection Department, Bureau of Housing and Construction, Treatment and Recycling Institution, etc., should be regulated. Problems and countermeasures of the pollution prevention of industrial waste generated in fire and explosion accidents are also presented.
Keywords
Industrial construction program; Policy and management; Pollution prevention; Responsibilities of different departments; Workshop structure
9.1. Pollution Prevention Methods Applied in Industrial Workshop Structures
9.1.1. Pollution Protection Design and Construction
Construction and demolition (C&D) waste is generated in the process of construction, renovation, and demolition of building products. The life cycle of building materials includes “conceptual design phase—construction acceptance phase—operation and service phase—end of service phase—regeneration phase.” In this section, countermeasures for heavy metal contaminated C&D waste management have been put forward based on the whole life cycle of construction products. Firstly, pollution control should be taken into consideration from the design and construction phase.
The pollution sources of heavy metal contaminated C&D waste are mainly the mutual contact between the medium containing heavy metals and the structure. Therefore there should be close relationship between source reduction and pollution prevention. Sophisticated antipollution and anticorrosion methods can be devised and performed in the design and construction phase of construction projects to avoid direct contact with pollutants, thus reducing the possibility of heavy metal exposure.
A number of industrial plants built before 2000 tend to be of low degree of standardization, lack of supporting anticorrosion, and anticorrosion measures after decades of service, which ultimately resulted in infiltration of contaminants. Heavy metal pollution, particularly evident in electroplating and metallurgical industry, was presented for many years. In buildings and structures constructed within or before this period, the aim of anticorrosion design and construction was to enhance the operation, while pollution prevention was often been neglected.
9.1.1.1. Grade of Protection
To prevent heavy metal pollution in the selection stage of building materials the corrosive effect of commonly used liquid solution containing heavy metals and salts on building materials should be taken into consideration. According to the provisions of corrosive level in “Industrial Construction Anticorrosion Design” (GB 50,046-2008) the corrosion degree can be classified in four grades: strong, moderate, weak, and minor in electroplating, metallurgy, and other industries, which are shown in Tables 9.1 and 9.2. The selection of protection materials should be based on the corrosion intensity.
9.1.1.2. Selection of Materials
Selection of ground layer materials is listed in Table 9.3. In industrial plant design, pollution prevention should be strengthened, and appropriate selection of the ground floor should be made in relevant regions involving the agents containing heavy metals. For example, acid-resistant bricks and stones should be used as the main materials of the floors and walls around the tanks in electroplating workshops, where as asphalt mortar, anticorrosion wear coatings, self-leveling resin coating, polymer cement mortar, concrete, and other building materials should not be applied in these kinds of regions. For heavily polluted areas, such as the building materials of the electroplating and wastewater treatment tanks, the depth of acid-resistant bricks and stones should not be less than 30 mm. Resin-based materials or water glass–based materials can be used as the masonry materials. Meanwhile, thick protective coatings should be set on the surface.
Table 9.1
Corrosion Grades of Liquid Solution to the Building Materials
| Solution | pH or Concentration | Reinforced Concrete, Prestressed Concrete | Cement, Plain Concrete | Sintered Brick | |
| Inorganic acid | Sulfuric acid, hydrochloric acid, nitric acid, chromic acid, plating solution, electrolyte, acid water (pH) | <4.0 | Strong | Strong | Strong |
| 4.0–5.0 | Moderate | Moderate | Moderate | ||
| 5.0–6.5 | Weak | Weak | Weak | ||
| Alkali | NaOH (%) | >15 | Moderate | Moderate | Strong |
| 8–15 | Weak | Weak | Strong | ||
| Ammonia (%) | ≥10 | Weak | Minor | Weak | |
| Salt | Sulfate of sodium, potassium, sodium, magnesium, copper, cobalt, iron (%) | ≥1 | Strong | Strong | Strong |
Table 9.2
Corrosion Grades of Solid Agent to the Building Materials
| Solubility | Hygroscopicity | Agent | Relative Humidity | Reinforced Concrete, Prestressed Concrete | Cement, Plain Concrete | Ordinary Carbon Steel | Sintered Brick | Wood |
| Insoluble | – | Carbonates and sulfates of barium and lead, oxides and hydroxides of chromium | >75 | Weak | Minor | Weak | Minor | Weak |
| 60–75 | Minor | Minor | Weak | Minor | Minor | |||
| <60 | Minor | Minor | Weak | Minor | Minor | |||
| – | Hard | Nitrate of barium and lead | >75 | Weak | Weak | Moderate | Weak | Weak |
| 60–75 | Weak | Weak | Moderate | Weak | Weak | |||
| <60 | Minor | Minor | Weak | Minor | Minor | |||
| – | Easy | Sulfate of chromium, nickel, manganese, and copper | >75 | Moderate | Moderate | Strong | Moderate | Moderate |
| 60–75 | Moderate | Moderate | Moderate | Moderate | Weak | |||
| <60 | Weak | Weak | Moderate | Weak | Minor |
Table 9.3
Selection of Floor Surface Materials
| Medium | Bulk Floor Surface | Monolithic Floor Surface | |||||||||||||
| Bulk Material | Mortar Joint | ||||||||||||||
| Type | Name (% or value) | pH or concentration | Acid-resistant brick | Acid-resistant stone | Sodium silicate mastic/mortar | Resin-bonded mastic/mortar | Asphalt mastic | Polymer cement mortar | Sodium silicate concrete | Polymer concrete | Resin mortar | Asphalt mortar | Corrosion-resistant coating | Polymer cement mortar | Dense concrete |
| Inorganic acid | Sulfuric acid | >70 | √ | √ | √ | O | × | × | √ | × | × | × | × | × | × |
| Nitric acid | >40 | ||||||||||||||
| Chromic acid | >20 | ||||||||||||||
| Sulfuric acid | 50–70 | √ | √ | √ | √ | × | × | √ | √ | √ | × | × | × | × | |
| Hydrochloric acid | ≥20 | ||||||||||||||
| Nitric acid | 5–40 | ||||||||||||||
| Chromic acid | 5–20 | ||||||||||||||
| Sulfuric acid | <50 | √ | √ | √ | √ | √ | O | √ | √ | √ | √ | O | O | × | |
| Hydrochloric acid | <20 | ||||||||||||||
| Nitric acid | <5 | ||||||||||||||
| Chromic acid | <5 | ||||||||||||||
| Pickle, plating solution (pH) | <1 | ||||||||||||||
| Acid solution | 1.0–4.0 | √ | √ | O | √ | √ | √ | O | − | √ | √ | √ | √ | × | |
| 4.0–5.0 | − | − | − | − | − | √ | − | − | √ | √ | √ | √ | O | ||
| 5.0–6.5 | − | − | × | − | − | √ | × | − | √ | √ | √ | √ | √ | ||
| Alkali | Sodium hydroxide | >15 | √ | √ | × | √ | O | O | × | − | √ | O | O | O | O |
| 8–15 | − | − | × | − | − | − | × | − | √ | √ | √ | √ | √ | ||
| Ammonia | ≥10 | − | − | × | − | − | − | × | − | √ | √ | √ | √ | √ | |
| Salt | Copper sulfate, cadmium sulfate | ≥1 | √ | √ | O | √ | O | O | O | − | √ | × | O | √ | × |
| Solid | Insoluable salt | Any | − | − | − | − | − | − | − | − | − | − | − | − | √ |
| Solid salt | Any | − | − | − | − | − | − | − | − | √ | √ | √ | √ | O | |
| Alkaline solid salt | Any | − | − | × | − | − | − | × | − | − | √ | √ | √ | √ | |
In metallurgy industry, granite and antiacid corrosion bricks should be applied as the layer protective materials. The hydrometallurgical process includes leaching, purification, filtration, sedimentation, evaporation, crystallization, etc., and most of them are performed in acid or alkaline salt solution. Therefore protection of the salt solution containing heavy metals and other pollution prevention is particularly important.
9.1.1.3. Surface Protection Coating
The coatings should be determined by the corrosion of industry solution and the service period of concrete structure. The materials of coatings include alkyd primer, iron red epoxy paint, PVC fluorescent prime, zinc-rich primer, etc.
1. Surface protection of concrete structure
If the corrosion intensity is high, 120, 160, and 200 μm protective layer should be applied for the service life of 2–5 a, 5–10 a, and 10–15 a, respectively. If the corrosion intensity is moderate the depth of protective layer should be at least 80 μm for the service life of 2–5 a, or replaced by treatment twice using a polymer slurry. If the corrosion intensity is low and the service life is 2–5 a, surface protection is not necessary in this situation. For the service life of 5–10 a, the depth of protection layer should be more than 80 μm or treating twice using polymer slurry could be replaced. For the service life of 10–15 a, the depth should be at least 120 μm.
2. Surface protection of masonry structure
If the corrosion intensity is high, 80, 120 , and 160 μm protective layer should be applied for the service life of 2–5 a, 5–10 a, and 10–15 a, respectively. If the corrosion intensity is moderate the protective layer should be treated twice using polymer slurry for the service life of 5–10 a. The depth of layer should be at least 80 and 120 μm for the service life of 5–10 a and 10–15 a, respectively. If the corrosion intensity is low and the service life is 2–5 a, surface protection is not necessary in this situation. For the service life of 5–10 a, the protection layer should be treated twice using polymer. For the service life of 10–15 a, the depth should be at least 80 μm.
9.1.2. Operation and Maintenance of Pollution Prevention
The exposure conditions of heavy metals during the service period of industrial structures largely determine the levels of pollution when they ultimately become C&D waste. The safe production, strict operation, and regular maintenance will become an important part of pollution prevention.
Pollution control during the service period of industrial structures should be focused on. The managing personnel are responsible for the operations and maintenance of pollution prevention. The operating workers have the obligation to identify and report problems. In industrial manufacturing processes, relative equipment which might be exposed to pollutants should be placed in an enclosed system to avoid the spilling, leakage or dribbling, or pollutants.
Timely repair and maintenance should be performed on the damage caused during manufacture. In the case of emergency, pollutants should be removed efficiently to avoid the spread of contamination. If there is corrosion on prevention materials and the pollutants infiltrate, the corrupted debris should be removed and the rest should be washed by diluted alkali and water before reinforcement. The stripped C&D waste containing heavy metal and organic pollutants is sent for harmless treatment before landfill.
9.2. Recommendation on Supervision and Management of Industrial Construction and Demolition Waste
9.2.1. Guidance of Pollution Prevention and Management (A Case Study in China)
The main responsibilities and organization of local housing and urban construction departments and environmental protection departments should be adjusted. The proposed regulatory mode and preliminary plan in China is shown in Fig. 9.1. As a case study in China the identification of C&D waste pollution is carried out by relevant qualified companies certificated by the Department of Environmental Protection, contaminated C&D waste is supervised and managed by the Department of Environmental Protection, where as ordinary C&D waste is sent for recycling by the housing and urban construction administrative departments. The relevant qualified companies are responsible for the subsequent treatment. Construction of solid waste management center should be strengthened. For the demolition or renovation of all chemical and metallurgical plants, environmental impact assessment should be carried out.
9.2.2. Problems and Countermeasures of Pollution Prevention of Industrial Waste Generated in Fire and Explosion Accidents
Main characteristics of C&D waste generated in fire and explosion accidents are listed as follows:
1. Heavy metals and organic pollutants largely exist, especially those from chemical, metallurgical, and pesticide industries. About 1–2% of all these C&D waste are hazardous waste, up to 1–2 million t/a without any treatment. Huge amounts of these wastes will generate and the pollutants will spread when the fire and explosion accident breaks out.
Figure 9.1 Recommendation on the administration of industrial construction and demolition waste in China.
2. Lots of hazardous substances will leak in explosion, most of which transmit into the atmosphere and aquatic system, others attach on the surface of C&D waste or soil. The existing emergency plans mainly focus on the monitoring of the atmosphere and surrounding water, mostly limited on conventional pollutants like nitrogen oxides and sulfur monoxide, etc. No sufficient attention has been paid to this situation, and the knowledge of the chemical materials and multiple contaminants generated still lacks. Most waste is stacked and discarded in a centralized way.
Recommendations on the pollution prevention and control of industrial C&D waste produced during fire and explosion accidents.
1. Laws and standards on industrial C&D waste produced during fire and explosion accidents should be established; the main focuses should be its pollution prevention regulations, collection and transportation regulations, identification criteria, disposal alternatives, etc.
2. Identification and classified management responsibilities of C&D waste produced during fire and explosion accidents should be established.
The waste should be divided into hazardous waste and ordinary waste. For those C&D waste with the spilling or leakage of dangerous substances, those with high volatility and low flash point, and those with high toxicity should be collected separately as hazardous wastes. The remaining C&D waste should be on-site investigated, sampled, and identified by environmental protection departments so that the scope of possible diffusion range of contamination is marked and the physicochemical properties are publicized. The housing and urban construction department, cooperating with fire department, executes the treatment work until all hazardous waste has been cleared as confirmed by Department of Environmental Protection.
3. In situ standardized disposal of C&D waste after accident should be developed.
C&D waste generated in accidents should be sorted based on the identification. Ordinary waste and heavy metal contaminated waste should be cleaned by elution of citric acid, where as organic pollutants contaminated waste should be treated using microwave heating method. Those C&D waste in which chemical materials might exist should be spilled by dry powder or foam in case of reburning and then should be humidified to prevent the diffusion of dust. In situ disposal or centralized transfer should be performed after being stabilized.
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