Briefly introduce the advantages and disadvantages of several common industrial park sewage treatment processes

Wastewater is one of the main causes of damage to the natural environment, and its source is mostly the discharge of wastewater caused by various production processes. Therefore, it is required that every industrial park should be equipped with industrial wastewater treatment equipment. However, when selecting, different sewage treatment processes have different treatment effects on different industrial wastewater. The editor introduces the advantages and disadvantages of several common industrial park wastewater treatment processes, hoping to help everyone make a reasonable choice.

1、 A2/O process

A2/O process is the abbreviation of Anaerobic Anoxic Oxic, which stands for anaerobic anoxic aerobic biological nitrogen and phosphorus removal process. This process generally achieves a treatment efficiency of 90% to 95% for BOD5 and SS, over 70% for total nitrogen, and around 90% for phosphorus. It is generally suitable for large and medium-sized urban sewage treatment plants that require nitrogen and phosphorus removal.

However, the infrastructure and operating costs of A2/O process are higher than those of ordinary activated sludge process, and the operation and management requirements are high. Therefore, for the current situation in China, this process is only adopted when the treated sewage is discharged into closed water bodies or slow-moving water bodies, causing eutrophication and affecting the water supply source.

1. Advantages:

(1) The pollutant removal efficiency is high, the operation is stable, and it has good resistance to impact loads.

(2) Good sludge settling performance.

(3) The organic combination of anaerobic, anaerobic, and aerobic environmental conditions and different types of microbial communities can simultaneously remove organic matter, nitrogen, and phosphorus.

(4) The denitrification effect is affected by the reflux ratio of the mixed solution, while the phosphorus removal effect is affected by the presence of dissolved oxygen (DO) and nitrate oxygen in the refluxed sludge. Therefore, the denitrification and phosphorus removal efficiency cannot be very high.

(5) In the process of simultaneous deoxygenation, phosphorus removal, and organic matter removal, the process flow is simple and the total hydraulic retention time is less than other similar processes.

(6) Under the alternating operation of anaerobic anaerobic aerobic, filamentous bacteria do not reproduce in large numbers, and the SVI is generally less than 100. Sludge expansion will not occur.

(7) The phosphorus content in sludge is high, generally above 2.5%.

2. Disadvantages:

(1) The volume of the reaction tank is larger than that of the A/O denitrification process.

(2) The sludge has a large reflux rate and high energy consumption.

(3) The cost for small and medium-sized sewage treatment plants is relatively high.

(4) The economic benefits of biogas recycling and utilization are poor.

(5) Chemical phosphorus removal is required for sludge leachate.

2、 Traditional activated sludge process

The activated sludge process is a widely used aerobic biochemical treatment technology for wastewater, which mainly consists of an aeration tank, a secondary sedimentation tank, an aeration system, and a sludge reflux system.

1. Advantages:

The process is relatively mature, with accumulated operational experience and stable operation; The removal efficiency of organic matter is high, and the removal rate of BOD5 is usually 90% to 95%; The aeration tank has a low ability to withstand impact loads; Suitable for large urban sewage treatment plants with stable inlet water quality and high treatment requirements.

2. Disadvantages:

The imbalance between oxygen demand and oxygen supply is large, with insufficient oxygen supply at the head of the pool and greater oxygen supply at the end, resulting in waste; The traditional activated sludge method has a long residence time in the aeration tank, a large volume, a large footprint, high infrastructure costs, and high electricity consumption; The efficiency of deoxygenation and phosphorus removal is low, usually only 10% to 30%.

3、 SBR process

The treatment process is mainly completed by several purification processes, including initial removal and adsorption, microbial metabolism, formation of flocs, and flocculation sedimentation performance. The core of SBR technology is the SBR reaction tank, which integrates functions such as homogenization, primary sedimentation, biodegradation, and secondary sedimentation into one tank, without a sludge reflux system. Especially suitable for occasions with intermittent emissions and significant flow changes.

1. Advantages:

(1) The ideal push flow process increases the driving force of biochemical reactions, improves efficiency, and alternates between anaerobic and aerobic conditions in the pool, resulting in good purification effects.

(2) Stable operation effect, sewage settles in an ideal static state, requiring short time, high efficiency, and good effluent quality.

(3) Resistant to impact loads, with retained treated water in the pool, it has a diluting and buffering effect on sewage, effectively resisting the impact of water volume and organic pollutants.

(4) Each process in the manufacturing process can be adjusted according to water quality and quantity, ensuring flexible operation.

(5) Less processing equipment, simple structure, easy operation and maintenance management.

(6) There is a concentration gradient of DO and BOD5 in the reaction tank, which effectively controls the expansion of activated sludge.

(7) The SBR system itself is also suitable for modular construction methods, which is beneficial for the expansion and renovation of wastewater treatment plants.

(8) Denitrification and phosphorus removal can be achieved by appropriately controlling the operating mode, alternating between aerobic, anoxic, and anaerobic states, resulting in good denitrification and phosphorus removal effects.

(9) The process flow is simple and the cost is low. The main equipment only has one sequencing batch intermittent reactor, without a secondary sedimentation tank or sludge reflux system. The regulating tank and primary sedimentation tank can also be omitted, with a compact layout and low footprint.

2. Disadvantages:

(1) Intermittent cycle operation requires high self-control.

(2) Variable water level operation increases power consumption.

(3) The efficiency of nitrogen and phosphorus removal is not very high.

(4) The stability of sludge is not as good as anaerobic nitrification.

4、 A/O process

The A/O process originated in the 1970s and has been widely used due to its ability to degrade organic matter and remove nitrogen, as well as its convenient operation and management. Due to the fact that sewage treatment processes are determined based on various factors such as the amount, quality, effluent requirements, and local conditions of sewage, small and medium-sized urban domestic sewage treatment stations generally use processes such as A/O.

1. Advantages:

(1) High efficiency: This process has a high removal effect on organic matter, ammonia nitrogen, etc. in wastewater. When the total residence time is greater than 54 hours, the effluent after biological denitrification can be treated with coagulation and sedimentation to reduce the COD value to below 100mg/L, and other indicators can also meet the discharge standards, with a total nitrogen removal rate of over 70%.

(2) Simple process, low investment, and low operating costs: This process uses organic matter in wastewater as the carbon source for denitrification, so there is no need to add expensive carbon sources such as methanol.

2. Disadvantages:

(1) Due to the lack of an independent sludge return system, it is not possible to cultivate sludge with unique functions, resulting in a lower degradation rate of difficult to degrade substances.

(2) To improve denitrification efficiency, it is necessary to increase the internal circulation ratio, which increases operating costs. In addition, the internal circulation liquid comes from the aeration tank and contains a certain amount of DO, which makes it difficult to maintain the ideal anoxic state in section A, affecting the denitrification effect and making it difficult to achieve a denitrification rate of 90%.

5、 Biofilm process

Biofilm method is an artificial enhancement of soil self purification process, which mainly removes dissolved and colloidal organic pollutants in wastewater, and also has a certain nitrification ability for ammonia nitrogen in wastewater. The biofilm method has a wide range of applications in the treatment of industrial wastewater.

1. Advantages:

(1) Microbial diversity and a long food chain are beneficial for improving sewage treatment efficiency and unit area treatment load.

(2) Segmented operation of advantageous microbial communities is beneficial for improving the degradation efficiency of microorganisms towards organic pollutants and increasing the removal rate of difficult to degrade pollutants, thereby enhancing the nitrogen and phosphorus removal efficiency.

(3) Strong adaptability to changes in water quality and quantity, and enhanced resistance to impact loads.

(4) Good settling performance of sludge, easy solid-liquid separation, low residual sludge production, reduced sludge treatment costs, and thus reduced investment costs.

(5) Suitable for the treatment of low concentration wastewater.

(6) Easy to maintain, easy to operate and manage, low energy consumption.

2. Disadvantages:

Compared with activated sludge process, biofilm process requires higher environmental temperature, and high or low temperature can affect the activity of biofilm, causing necrosis and shedding of biofilm.

The above is a comparison of industrial park sewage treatment processes conducted by Daquan editor for everyone. These sewage treatment processes have their own advantages and disadvantages, and each has its own advantages when facing different industrial production. However, the specific choice still needs to be based on the treatment effect and the conditions of the enterprise. After determining the treatment process, it is necessary to purchase corresponding process sewage treatment equipment and carry out later operation and management to ensure the stable operation of the equipment.