Sewage treatment technology

About:

Under normal circumstances, the actual sewage often contains a variety of pollutants, and only a single treatment method can not achieve the desired effect. In order to obtain a better treatment effect at a lower treatment cost, it is often necessary to combine several treatment technologies according to a certain primary and secondary relationship and order according to a variety of factors such as the quality of sewage, the amount of water, the degree of treatment, the possibility of recycling useful substances and the conditions of the capital site, to form a complete purification treatment system.

Process application:

The type of domestic sewage treatment process not only determines the sewage purification effect, but also determines the sludge generation and sludge treatment method in the sewage purification process [3]. sewage treatment (wastewater treatment) : The process of purifying sewage in order to make it meet the water quality requirements for draining a body of water or reuse. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, catering and other fields, but also more and more into the daily life of ordinary people.

Selection criteria:

1) The municipal sewage treatment process should be optimized and determined according to the treatment scale, water quality characteristics, environmental functions of the receiving water body and the actual situation and requirements of the local area after a comprehensive technical and economic comparison.

2) The main technical and economic indicators of process selection include: investment per unit of water treatment, investment reduction per unit of pollutants, power consumption and cost per unit of water treatment, power consumption and cost reduction per unit of pollutants, land area, reliability of operation performance, management and maintenance difficulty, overall environmental benefits, etc.

3) The effluent water quality should be determined realistically and the process design parameters should be optimized. It is necessary to conduct detailed investigation or determination of the current water quality characteristics and pollutant composition of sewage, and make reasonable analysis and prediction. When the water quality is complex or special, the dynamic test of wastewater treatment process should be carried out, and pilot study should be carried out if necessary.

4) Actively and prudently adopt efficient and economical new processes. For the new process applied for the first time in China, it must go through pilot and production tests to provide reliable design parameters before being applied [1].

By process:

Classification of Water Pollution Control Engineering

Separation technology of insoluble pollutants:

1, gravity sedimentation: sedimentation tank (advection, vertical flow, swirl, aeration), sedimentation tank (advection, vertical flow, radial flow, oblique flow);

2, coagulation and clarification;

3, buoyancy floating method: oil separation, air floating;

4, others: resistance retention, centrifugal force separation method, magnetic separation method

Biochemical transformation technology of pollutants:

1, Activated sludge method: SBR, A/O, A/A/O, oxidation ditch, etc

2, biofilm method: biological filter, biological turntable, biological contact oxidation pool, etc

3. Anaerobic biological treatment: anaerobic digestion, hydrolytic acidification pool, UASB, etc

4. Biological treatment under natural conditions: stabilization pond, ecosystem pond, land treatment method

Chemical conversion technology of pollutants:

1. Neutralization method: acid-base neutralization

2, chemical precipitation method: hydroxide precipitation, ferrite precipitation, other chemical precipitation

3, REDOX method: chemical oxidation method, chemical reduction method, electrochemical method

4, chemical and physical disinfection method: ozone, ultraviolet, chlorine dioxide, chlorine gas, sodium hypochlorite

Physicochemical separation technology of dissolved pollutants:

1. Adsorption method

2. Ion exchange method

3, membrane separation method: diffusion dialysis, electrodialysis, reverse osmosis, ultrafiltration, nanofiltration, microfiltration

4, other separation methods: blowing and gas extraction, extraction, evaporation, crystallization, freezing

Classification according to common sewage treatment methods

Physical method: Physical or mechanical separation process. Filtration, precipitation, centrifugal separation, floating, etc

Chemical method: The conversion process of adding chemical substances to react with harmful substances in sewage. Neutralization, oxidation, reduction, decomposition, coagulation, chemical precipitation, etc

Physicochemical method: physicochemical separation process. Gas stripping, blowing, adsorption, extraction, ion exchange, electrolytic electrodialysis, reverse osmosis, etc

Biological method: The metabolic process in which microorganisms oxidize and decompose organic matter in sewage. Activated sludge, biological filter, biological turntable, oxidation pond, anaerobic digestion, etc

Chemical classification of wastewater