The applicable conditions of the sewage treatment process and the determination of the sewage treatm

1. The adaptation conditions of BOD, this problem is quite strange, generally speaking, if you want to deal with a kind of water, the higher the BOD, the better, because it proves that the biodegradability of this water is strong, and the treatment efficiency is high in biological contact oxidation, biological turntable, biofilm, and activated sludge.

2. The temperature depends on whether the bacteria you are cultivating are high-temperature bacteria, medium-temperature bacteria or low-temperature bacteria, but the basic sewage treatment is medium temperature, so 35 degrees Celsius is the best.

3. Of course, pH is 7 is the best, but sometimes according to different processes, pH is slightly higher in some links, such as some activated sludge factories in order to reduce the incidence of filamentous bacteria in aerobic ponds, deliberately increase pH to 8-9, which is not clear. There is no standard to speak of.

The following points need to be considered in the determination of the wastewater treatment process:

First, the degree of sewage treatment.

This is the main basis for the selection of sewage treatment processes. In principle, the degree of sewage treatment depends on the water quality characteristics of the effluent, the destination of the treated water and the self-purification capacity of the water into which the effluent flows. However, at present, the determination of the degree of sewage treatment is mainly in accordance with the requirements of the relevant legal system and technical policies of the state.

Usually, the environmental management department controls the discharge concentration of sewage according to the "Comprehensive Sewage Discharge Standard" and related industry discharge standards, and some areas with a higher level of economic development also stipulate stricter local discharge standards. Therefore, no matter what kind of sewage needs to be treated, no matter what kind of treatment process and degree of treatment is adopted, it should be based on and premise that the effluent of the treatment system can meet the standard. Prevent and control environmental pollution of water bodies in accordance with the requirements of laws, regulations, and policies.

Second, the quality of sewage.

For example, the water quality of domestic sewage is usually relatively stable, and general treatment methods include acidification, aerobic biological treatment, disinfection, etc. The industrial wastewater should be reasonably selected according to the specific water quality situation. In particular, it should be pointed out that for the use of aerobic biological treatment process to treat wastewater, it is necessary to pay attention to the biodegradability of wastewater, usually requiring COD, if it cannot meet the requirements, anaerobic biological hydrolysis acidification can be considered to improve the biodegradability of wastewater, or the physical or chemical method of non-biological treatment can be considered.

3. Local natural and social conditions.

Local topography, climate and other natural conditions also have a certain impact on the selection of wastewater treatment processes. If the local climate is cold, the process should be adopted to ensure that the water quality meets the standards even in the low temperature season after taking appropriate technical measures. Local social conditions such as raw materials, water and electricity** are also factors that should be taken into account in the selection of processes.

Fourth, the amount of sewage.

In addition to water quality, the amount of sewage is also one of the influencing factors. For sewage with large changes in water quantity and quality, the use of processes with strong resistance to shock loads should be considered first, or the establishment of buffer equipment such as regulating tanks should be considered to minimize adverse effects.

5. Construction and operation costs.

When considering construction and operation costs, it should be a prerequisite that the treated water meets the water quality standards. Under this premise, the process of low engineering construction and operation cost should be paid attention to. In addition, reducing the floor space is also an important measure to reduce construction costs.

In short, the selection of sewage treatment process should comprehensively consider various factors, and the technical and economic comparison of various schemes can make a suitable choice.

The sewage treatment process is as follows:

1. The wastewater first flows to the flocculation sedimentation tank after passing through the grid and screen, in order to make the treatment effect good, the coagulant is added to the flocculation sedimentation tank, so that the suspended solids in the wastewater treatment effect is better, the coagulation dosing also plays a role in regulating the wastewater, and the wastewater after flocculation and precipitation flows into the pre-aeration conditioning tank.

2. Air is introduced into the aeration conditioning tank to play the role of pre-aeration adjustment. The homogeneously regulated wastewater is pumped into a primary floating packing biochemical tank.

3. The aeration head with high oxygenation efficiency is installed in the biochemical tank and loaded with floating filler, which has proved that this technology has a high removal efficiency for COD and BOD. The wastewater in the primary floating filler biochemical tank flows into the secondary floating filler biochemical tank, and the method is the same in the second pool.

4. The water of the secondary floating packing biochemical tank flows into the inclined plate sedimentation tank. The addition of polypropylene honeycomb inclined pipe to the pool can greatly improve the settlement efficiency, in addition, the hydraulic load is high, the residence time is short, and the floor area is small.

5. The sludge precipitated by the coagulation sedimentation tank and the inclined plate sedimentation tank is discharged into the sludge thickening tank, and then dewatered by the sludge dewatering machinery.

6. The water discharged from the inclined plate sedimentation tank flows into the clear water tank and is discharged after testing.

The design of urban sewage treatment engineering is a highly comprehensive system engineering, involving many disciplines and related departments, and any unreasonable link will have an impact on the engineering design and cause different degrees of losses.

basic conditions; Treatment scale: The determination of treatment scale is mainly related to the following factors:

The urban population includes both permanent residents and floating populations. It is usually determined based on the near-, long-term and long-term population** of the city's master plan. When the overall urban plan has been prepared earlier, has not been revised or is being revised, it is necessary to verify the current population and conduct a reasonable analysis and **.

At the same time, when determining the population, special attention should be paid to the characteristics of the population peak in the tourist city in the peak tourist season and the impact on the urban water volume change system.

The nature of the city and the economic level of the city are different, the natural conditions, the degree of economic development, the people's living habits and housing conditions are different, and the water consumption standards of urban residents are different, so the amount of urban sewage is also different.

Urban drainage systemThe urban drainage system is divided into a diversion system and a confluence system. Generally, new cities, new expansion areas, new development zones and cities with better economic conditions should adopt the diversion system; Due to historical reasons, the old urban areas that have been built in some large and medium-sized cities are generally confluence system, which can be transformed into interception confluence system. Depending on the city, different drainage systems can be used in different areas of the same city.

The choice of urban drainage system directly affects the scale of sewage volume, when the diversion system is adopted, the design sewage volume is all urban sewage (including domestic sewage and industrial wastewater, etc.), when the interception confluence system and the diversion system combination system are adopted, the amount of rainwater discharged into the interception confluence system must be considered, the rainwater volume is related to the design interception multiple, and should be reasonably determined after scientific analysis.

The amount of industrial wastewater is different due to the different urban structure, industrial type and industrial proportion, so the amount of industrial wastewater and water quality are different.

According to the "Construction Standards for Urban Sewage Treatment Engineering Projects", the bent water of the industrial waste section is treated by the factory itself, and after reaching the "Water Quality Standard for Sewage Discharge into Urban Sewers" (CJ3082-1999), it will be prioritized to be included in the urban sewage collection system and treated in combination with urban domestic sewage. Therefore, the amount of industrial wastewater is an important part of the treatment scale of the urban sewage treatment plant, and the amount of wastewater must be fully investigated and studied to reasonably determine the amount of industrial wastewater.

The degree of perfection of the sewage pipe network is very important for the determination of the design scale of the urban sewage treatment plant. The role of the pipe network is mainly to undertake the collection and transportation of urban sewage.

At present, the degree of pipe network construction in each city is different, and the transportation capacity is different, if it is defined as "sewage collection rate", the current sewage collection rate and planned sewage collection rate of each city are different. When the amount of sewage treated within the design basin is determined, it must be multiplied by the sewage collection rate to obtain the actual amount of sewage discharged into the sewage treatment plant, in other words, when it is necessary to ensure that the treatment plant has a certain treatment capacity, there must be a corresponding scale of supporting sewage pipe network built simultaneously.

Principles of Industrial Wastewater Treatment.

1) Eliminate unreasonable productsFor some traditional wastewater treatment products with low yield and high difficulty, we must be determined to replace them with high-yield, high-tech products. If the annual profit of a product is less than the annual cost of wastewater treatment, it should be determined that the product is discontinued and replaced with a less polluting and easy-to-treat product.

2) Strengthen management and reduce pollution. Business management is also an important factor in the prevention and control of pollution. Such as equipment running, running, dripping, leaking; Production accidents or product scrapping caused by non-compliance with operating procedures, resulting in a large amount of high-concentration wastewater; Flushing equipment and grounds with large amounts of water, resulting in an increase in the volume of wastewater; The cooling water is not separated from the production wastewater, which will increase the amount of wastewater and the difficulty of wastewater treatment.

3) Establish regional small sewage treatment plants in areas where factories are concentrated. Rather than applying the principle of "who pollutes, who cleans", it is better to strengthen the connection between enterprises and consider pollution control measures as a whole. If necessary and possible, we can centralize the wastewater from various factories and establish a unified sewage treatment plant, implementing a "who pollutes, who pays" control method.

Due to the different products in different factories, the quality of wastewater is also different. For example, the wastewater from some factories is acidic, while the wastewater from other factories is alkaline, and treating them together can reduce the cost of neutralizer treatment. Some plants discharge wastewater with high salinity and low chemical oxygen demand, while others have high concentrations and are readily biodegradable.

If it is treated separately, it is a difficult wastewater to treat. However, if they are put together for biochemical treatment, due to the improvement of water quality conditions, it can not only reduce the difficulty of wastewater treatment, but also improve the treatment efficiency.

4) Improve the recycling rate of waterIn order to reduce the amount of wastewater, we must first make a fuss about wastewater. For example, water can be considered or reused to increase the rate of water and minimize external drainage. The water resource recycling rate of some advanced foreign enterprises has reached more than 96%, while the water resource recycling rate of domestic fast selling enterprises is still at a low level of 20-50%, and there is still a lot of potential to be tapped.

Improving the recycling rate of production water can not only reduce environmental pollution, but also reduce the supplementary consumption of fresh water per mu, which can alleviate the increasingly tight water resources problem to a certain extent. In wastewater treatment, the recycling of treated wastewater should also be considered as much as possible.

1.Priority should be given to non-toxic production processes to replace or reform backward production processes, and the production process should be eliminated or reduced as much as possible.

2.In the process of using toxic raw materials and producing toxic intermediate products and products, strict operation and supervision are carried out to eliminate dripping and reduce loss.

3.Sewage containing highly toxic substances should be separated from other sewage for treatment and useful substances.

4.Sewage with a large flow rate and light pollution should be properly treated and circulated to make it suitable for use.

5.Organic wastewater, which is similar to municipal sewage, can be discharged into the municipal sewage system for treatment.

6.Some biodegradable toxic sewage should be treated and discharged into the urban sewer according to the allowable discharge standard, and then further biochemical treatment.

7.Toxic effluents containing non-biodegradable should be treated separately and should not be discharged into urban sewers. The development trend of industrial wastewater treatment is to use sewage and pollutants as useful resources** or implement closed-circuit circulation.

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

2) The main technical and economic indicators of process selection include: investment per unit of water volume, reduction of investment per unit of pollutants, power consumption and cost per unit of water volume, reduction of power consumption per unit of source of pollutants and cost of loss, high sensitivity product of the ground, reliability of operation performance, difficulty of management and maintenance, overall environmental benefits, etc.

3) The quality of sewage inlet water should be realistically determined, and the process design parameters should be optimized. The current water quality characteristics and pollutant composition of the sewage must be investigated or measured in detail, and a reasonable analysis must be made**. When the water quality composition is complex or special, the dynamic test of the sewage treatment process should be carried out, and the pilot study should be carried out if necessary.

4) Actively and prudently adopt new processes that are efficient and economical. 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 application.

The AFF process is a simple reclaimed water reuse process, which is characterized by setting up a sedimentation tank in the activated sludge tank, and pumping the supernatant into the asymmetry fiber filter (AFF) through the water pump, filtering the effluent directly for discharge, or entering the MBFB combined process for advanced treatment, and the backflushed sludge is directly returned to the activated sludge tank.

The MBFB combined process is an advanced reclaimed water reuse process, which is based on the biofluidized bed, with POW-dered activated carbon (PAC) as the carrier, combined with the solid-liquid separation technology of the membrane bioreactor process (MBR) process, so that the reactor integrates the physical adsorption of activated carbon, the biological purification of the bioreactor and the efficient separation of the membrane. The small molecule organic matter that is difficult to degrade in the water body is mass transferred and mixed with the activated carbon powder in the fluidized state under aeration conditions, and is adsorbed and enriched on the surface of the activated carbon, so that the surface of the activated carbon forms a local pollutant concentration area; Under the condition of high dissolved oxygen, microorganisms oxidize and decompose the small molecule organic matter enriched on the surface of the activated carbon, and then use the ceramic membrane separation system to separate the water from the suspended particles such as powder activated carbon that adsorbs organic matter, and further purify the sewage through cross-flow filtration, so that it can meet the standard of reclaimed water reuse. Studies have shown that MBFB can effectively remove ammonia nitrogen, COD and other refractory small molecule toxic organic compounds in micro-polluted water.