The mining and processing industry being complex, the issue of water use is of primary importance. Oil refinery wastewater is highly toxic and poses a serious environmental problem due to the high volume of water disposal. Besides, commercial oil products can be lost with wastewater and produced water. Use of contaminated produced water decreases the production rate of oil wells. Thus, one of the industry’s primary objectives is thorough and quality wastewater treatment to existing standards.
The capacity of oil refinery water rotation system can amount to 10000m3 and wastewater quantity can reach thousands of cubic meters per hour. Back water and wastewater are contaminated with oil products, suspended mechanical impurities, emulsions and solutes. Wastewater treatment must provide efficiency of the processing equipment within the specified framework, and wastewater treatment plants must minimize the dangerous effect of industrial production on the environment.
Wastewater treatment in mining and metallurgical industry
In terms of the wastewater amount produced Mining and metallurgical sector is in the top four alongside heat power industry (50% of industrial water use), chemical industry, and oil and gas industry. The negative effect on the natural water bodies is characteristic of metallurgical production – mining industry, beneficiation plants, blast-furnace ironmaking, steelmaking, coke and by-product process, electrochemical production, pipe-rolling production, metal working etc. The main water treatment techniques used in the industry are normally comprised of the physicochemical water treatment methods: neutralization, flocculation, coagulation, sedimentation, ion-exchange, evaporating, filtration, adsorption, biological purification, the electrochemical method and the electromagnetic (non-intrusive) method.
Industrial wastewater is normally purified using uninterrupted sedimentation and flocculation combined with filtration and dewatering, flotation under pressure coupled with uninterrupted removal of particles and activated carbon adsorption; ion-exchange units are used for selective wastewater deionazation. Ore flotation and further recycling and aqueous solution purification are employed as well.
For heating and cooling systems, parts washing and wet dust catching there are the following kinds of water treatment: providing the necessary quality of disposable water used for washing; providing the necessary quality of reusable water (for galvanizing, painting etc.).
The water categories used in machine industry:
– clarified water (no mechanical impurities, no color, no turbidity, no sediments, no iron or manganese impurities). It’s produced using mechanical filtration, adsorbtion filters etc.;
– softened water (no calcium or magnesium ions). It’s produced using ion-exchange resin filters;
– demineralized water (salinity less than 20 g/L). It’s produced on reverse osmosis units;
– distilled water (GOST 6709-72).
The cost of cooling lubricants is the main expense item of metal working. Replacement is a very challenging task. Used materials disposal (2-10% of mineral oils aqueous solutions) implies constantly growing expenses in order to meet the current environmental requirements.
Wastewater treatment in pulp and paper and textile industries
Pulping, bleaching and ink filtration require large amounts of water (350 m3 per ton). Flotation, coagulation, disk filters and strainers, ultra- and nanofiltration are the water treatment methods applied in water rotation cycles.
Sewage treatment in housing and communal services sector
Drinking water is prepared in accordance with sanitation rules and regulations (SanPin):
– mineral composition (demineralization);
– water softening (calcium salt) and dealkalization;
– removal of iron and manganese compounds;
– organic compounds removal and permanganate value correction;
– removal of heavy metal salts;
– removal of radon and other radioactive elements;
– pH correction;
– oxygenation and REDOX-potential correction;
The amount of hazardous substances formed during water treatment is strictly controlled:
– chlorine (0.3-0.5 mg/L);
– formaldehyde (0.05 mg/L);
– polyacrylamide (2.0 mg/L);
– polyphosphate (3.5 mg/L);
Thus, the problem of primary sewage treatment can be clearly seen, including the removal of organic matter and pollutants.
Wastewater treatment in building materials manufacturing