Integrated facilities for medical wastewater treatment

Integrated facilities for medical wastewater treatment
The sewage treatment equipment we produce is nationwide and can treat any type of high or low difficulty sewage.

Company advantages: Engaged in the sewage industry for a long time, with rich experience, large company scale, good reputation, equipped with installation and after-sales personnel from all over the country, currently covering prefecture level cities.

Equipment advantages: adopting new technologies and processes, with sufficient stock of various models of equipment, and a wide range of equipment applications (capable of treating wastewater from any industry).

Our main products include underground integrated sewage treatment equipment, air flotation equipment, sedimentation equipment, chlorine dioxide generators, dosing equipment, etc.

The main body of the UNITANK system is a rectangular reaction pool that is partitioned into several units, typically a three cell pool. Hydraulic connectivity between the three pools; Each tank is equipped with an aeration system, which can be supplied with air by a blower or used for mechanical surface aeration and mixing; The two outer tanks are equipped with effluent weirs and residual sludge discharge outlets, which alternate as aeration tanks and sedimentation tanks. Wastewater can enter any one of the three tanks, using continuous inflow and alternating cycle operation. By adjusting the operation of the system, time and space control of the treatment process can be achieved, forming aerobic, anaerobic, or anoxic conditions to achieve specific treatment goals.

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During operation, two tanks are in the aeration stage, while one of the side tanks is in a sedimentation state. The treated effluent is discharged from the weir mouth, and the remaining sludge is discharged from the bottom tank. For example, sewage enters from the left rectangular tank, which serves as an aeration tank. It flows from the connecting pipe to the middle rectangular aeration tank, and then through the connecting pipe to the right rectangular sedimentation tank. The treated water is discharged from the fixed weir, and the water flow direction is from left to right; After a certain period of time, close the inlet gate of the left pool and open the inlet gate of the middle pool. At this point, the left pool begins to stop aeration, and sewage flows from the middle pool to the right pool; After a brief transition period, close the inlet gate of the middle tank and switch to the right tank for water intake. At this point, the right tank is aerated, while the left tank undergoes static sedimentation before discharging water. The water flows from right to left, completing a switching cycle. This cycle repeats itself, and the sewage achieves the purification goal.
Due to the water level difference among the three ponds, water flows from one pond to the middle pond and then out from the other pond. At this time, the water level in the incoming pond is the highest and submerges the fixed weir's discharge tank. When the pond transitions from the aeration tank to the sedimentation tank, the water level will inevitably decrease. The sludge and sewage mixture remaining in the discharge tank must be removed and the tank must be washed with clean water. The discharged mixture and flushing water are collected in a dedicated tank and then lifted by a small water pump to the middle tank.

Aerobic granular sludge is a new technology in wastewater biological treatment Compared with the activated sludge flocs commonly used in the current activated sludge process, the advantage of aerobic granular sludge is that the activated sludge flocs grow into particles under certain conditions and settle much faster in water than the activated sludge flocs. Therefore, using aerobic granular sludge to treat wastewater can greatly increase the biological concentration in the aeration tank and shorten the settling time The concentration of activated sludge in the ordinary activated sludge method aeration tank is about 3000 mg · L-1, and the sedimentation time is 30 minutes to 2 hours. However, using aerobic granular sludge technology, the sludge concentration in the aeration tank can reach 10000-14000 mg · L-1, and the sedimentation time only takes 1-3 minutes. Compared with anaerobic granular sludge commonly used for treating high concentration wastewater and difficult to degrade wastewater, the cultivation time of aerobic granular sludge is about 1 week to 1 month, which is much shorter than the start-up time of anaerobic granular sludge, which is 6 months Therefore, aerobic granular sludge technology is expected to bring breakthrough progress to today's sewage biological treatment technology

However, the research on aerobic sludge granulation is still relatively short, and there is a lack of in-depth research on the formation process, mechanism, various environmental factors affecting aerobic granular sludge, and microbiology of granular sludge In addition, most of the research on aerobic granular sludge is conducted on a laboratory scale using artificially prepared water with higher organic matter concentrations (such as glucose) as the substrate, and less use is made of low organic matter concentration urban domestic wastewater to cultivate aerobic granular sludge On the other hand, urban domestic wastewater contains various pollutants with low COD content, usually less than 200 mg · L-1. Currently, traditional activated sludge methods are commonly used for the treatment of this type of wastewater, which have good treatment effects. However, traditional activated sludge treatment systems generally occupy a large area, have high construction costs, a large amount of residual sludge, high operating costs, and are prone to sludge expansion

The UNITANK process, also known as the integrated activated sludge process (alternating biological tank), consists of three rectangular tanks that are hydraulically connected. Each tank is equipped with oxygen supply equipment, which can use air blowing aeration or surface aeration. Rectangular tanks are set on both sides of the outer surface, with fixed effluent weirs and residual sludge discharge outlets. The tank can be used as both an aeration tank and a sedimentation tank, with the middle rectangular tank only serving as an aeration tank. The sewage entering the system can be controlled by the near water gate to enter any one of the three rectangular tanks in time sequence, as shown in Figure 1.
The UNITANK process is a new sewage treatment process today, which is a new variant and development of the SBR method. It not only has the main characteristics of the SBR system, but also can operate continuously at a constant water level like the traditional activated sludge process.

The UNITANK process can be regarded as a combination of "sequencing batch method", "ordinary aeration tank method" and "three ditch oxidation ditch method", which overcomes the disadvantages of intermittent water inlet in the "sequencing batch method", large footprint in the "three ditch oxidation ditch method", and multiple equipment in the "ordinary aeration tank method", and has synchronous nitrogen and phosphorus removal function. The typical UNITANK process consists of three water tanks, which are hydraulically connected and each tank is equipped with an aeration system. The outer two tanks are equipped with effluent weirs and sludge discharge outlets, which alternate between aeration tanks and sedimentation tanks.

Wastewater can enter any one of the three tanks, using continuous inflow and periodic alternating operation. Under automatic control, each tank is placed in aerobic, anoxic, and anaerobic states to complete the removal of organic matter and nitrogen and phosphorus. The UNITANK system has become an efficient, economical, flexible, and mature wastewater treatment process abroad. After research and application, the UNITANK system has become an efficient, economical, flexible, and mature wastewater treatment process.

The main body of the UNITANK system is a rectangular reaction pool that is partitioned into several units, typically a three cell pool. Hydraulic connectivity between the three pools; Each tank is equipped with an aeration system, which can be supplied with air by a blower or used for mechanical surface aeration and mixing; The two outer tanks are equipped with effluent weirs and residual sludge discharge outlets, which alternate as aeration tanks and sedimentation tanks. Wastewater can enter any one of the three tanks, using continuous inflow and alternating cycle operation. By adjusting the operation of the system, time and space control of the treatment process can be achieved, forming aerobic, anaerobic, or anoxic conditions to achieve specific treatment goals.
Ammonia stripping is a method of first adjusting the pH of wastewater to 10.8-11.5, and then allowing the wastewater to reflux with a large amount of air in the form of water droplets for mass transfer, thereby diffusing ammonia nitrogen in the water into the atmosphere in the form of NH3. This ammonia removal process is simple and easy to control, but there are two main issues:
(1) The efficiency of ammonia stripping is closely related to the pH value. In order to achieve a high removal rate of ammonia nitrogen, it is necessary to adjust the pH value of the sewage to alkaline, and alkali needs to be added. The higher the acidity in the raw water, the more alkali is consumed to adjust the pH; After deamination, the wastewater needs to be adjusted to neutral pH by adding acid or CO2, which will increase operating costs and also increase the dissolved solid content in the wastewater.

(2) The efficiency of ammonia stripping is closely related to water temperature and air temperature. The lower the temperature, the lower the efficiency of ammonia removal. At 20 ℃, the typical ammonia removal rate is 90% -95%, while at 10 ℃, the ammonia removal rate decreases to below 75%. In general, the gas to water ratio for stripping is above 3000. For an open system, the water temperature will tend to be * with the ambient temperature. If the ambient temperature is too low, it will greatly affect the stripping efficiency. If the ambient temperature is below 0 ℃, the ammonia removal tower will not be able to operate. Therefore, for the southern regions with higher temperatures, if the acidity in the water is not high, it is feasible to use the blow off method for denitrification. In the cold northern regions, it is not easy to use blow off denitrification.
Ion exchange for ammonia removal

Characteristics of membrane technology process
Compared with many traditional biological water treatment processes, MBR has the following main characteristics:
1、 High quality and stable effluent water quality
Due to the efficient separation effect of the membrane, the separation efficiency is much better than that of traditional sedimentation tanks. The treated effluent is extremely clear, with suspended solids and turbidity close to zero. Bacteria and viruses are greatly removed, and the effluent quality is better than the domestic miscellaneous water quality standard issued by the Ministry of Construction (CJ25.1-89). It can be directly reused as non potable municipal miscellaneous water.
At the same time, membrane separation also intercepts microorganisms in the bioreactor, allowing the system to maintain a high concentration of microorganisms. This not only improves the overall removal efficiency of pollutants by the reaction device and ensures good effluent quality, but also enables the reactor to adapt well to various changes in inlet load (water quality and quantity), withstand shock loads, and stably obtain high-quality effluent quality.

2、 Low production of surplus sludge
This process can operate under high volume load and low sludge load, with low residual sludge production (theoretically achieving zero sludge discharge), reducing sludge treatment costs.
3、 Small footprint, not limited by the setting location
The bioreactor can maintain a high concentration of microbial biomass, with a high volumetric load on the treatment device and a large footprint, resulting in significant cost savings; This process is simple, compact in structure, and occupies a small area. It is not limited by the installation location and is suitable for any occasion. It can be made into ground, semi underground, and underground types.
4、 Can remove ammonia nitrogen and difficult to degrade organic matter
Due to the interception of microorganisms in the bioreactor, it facilitates the retention and growth of slowly proliferating microorganisms such as nitrifying bacteria, thereby improving the nitrification efficiency of the system. At the same time, it can increase the hydraulic retention time of some recalcitrant organic compounds in the system, which is beneficial for improving the degradation efficiency of recalcitrant organic compounds.

Biochemical treatment for further degradation of COD in wastewater is a relatively economical treatment process, but its disadvantage is that the COD concentration in the treated effluent is difficult to reach a very low level. When the required COD value is very low, other measures still need to be taken; The activated carbon adsorption process is a technically reliable and economically feasible method, and the COD of the effluent can reach a level of about 10mg/L. The disadvantage is that it requires regular regeneration. If there is an activated carbon production plant nearby that provides carbon replacement services, the activated carbon adsorption process is an ideal method for deep sewage treatment; For the ozone pretreatment+biochemical treatment method, although it can achieve a lower level of COD in the effluent, using it as supplementary water for the circulating cooling system may not necessarily reduce the amount of scale production. At the same time, using ozone treatment will greatly increase infrastructure investment and operating costs, and operation management will also be complicated. Therefore, it should be carefully considered in practical engineering.
Removal of Ammonia Nitrogen
At present, the treatment technologies for wastewater containing ammonia nitrogen include biological nitrification, ion exchange, blow off, liquid membrane, chlorination or adsorption, and wet catalytic oxidation. For secondary biochemical effluent with ammonia nitrogen concentration of tens of mg/L, biological nitrification, blow off, and ion exchange are the most commonly used. When the ammonia nitrogen concentration is not high, chlorination should be used.

Biological nitrification method for ammonia removal
Biological nitrification and denitrification is the process of converting ammonia into nitrate under aerobic conditions using nitrifying bacteria and sub digesting bacteria. Both of these bacteria are chemoautotrophic. Under aerobic conditions, nitrifying bacteria first oxidize ammonia to nitrite, and then nitrifying bacteria further oxidize nitrite to nitrate. Many domestic sewage treatment plants have biological nitrification function to remove ammonia nitrogen from sewage. For treatment facilities that specifically consider biological nitrification, ammonia nitrogen in sewage can be removed to below 2mg/L.

The split membrane bioreactor separates the membrane components from the bioreactor. The mixed liquid in the bioreactor is pressurized by the circulation pump and sent to the filtration end of the membrane module. Under pressure, the liquid in the mixed liquid passes through the membrane and becomes the system's treated water; Solid substances, large molecular substances, etc. are trapped by the membrane and reflux back into the bioreactor with the concentrated solution. The characteristics of a split membrane bioreactor are stable and reliable operation, easy membrane cleaning, replacement, and addition; Moreover, the membrane flux is generally high. However, under normal conditions, in order to reduce the deposition of pollutants on the membrane surface and extend the cleaning cycle of the membrane, it is necessary to use a circulation pump to provide a higher cross flow velocity on the membrane surface. The water flow circulation volume is large, the power cost is high, and the shear force generated by the high-speed rotation of the pump can cause certain microbial cells to become inactive.

The integrated membrane bioreactor involves placing membrane components inside the bioreactor. The incoming water enters the membrane bioreactor, where most of the pollutants are removed by the activated sludge in the mixed solution, and then filtered out by the membrane under external pressure. This form of membrane bioreactor eliminates the need for a mixed liquid circulation system and relies on water suction, resulting in relatively low energy consumption; It occupies more space and is more compact than a separate type, and has received special attention in the field of water treatment in recent years. However, the membrane flux is generally relatively low, making it prone to membrane fouling and difficult to clean and replace after fouling.
The composite membrane bioreactor also belongs to the integrated membrane bioreactor in form, with the difference being the addition of fillers inside the bioreactor to form a composite membrane bioreactor, which changes certain characteristics of the reactor.

Activated carbon adsorption process
Activated carbon adsorption method is a technically reliable and economically feasible physical and chemical treatment method. Its principle is to use the huge surface area of activated carbon to adsorb organic matter in water. It has been widely used in production and application abroad for many years. Generally, the secondary effluent of activated sludge process is first subjected to coagulation sedimentation and filtration, and then activated carbon adsorption is carried out. The COD of the effluent from the carbon tower can reach about 10mg/L, and the weight ratio of adsorbed COD to activated carbon can reach 0.3-0.8. The operating effect is relatively ideal. Therefore, the use of activated carbon to treat the secondary effluent of sewage plants is technically mature and reliable.

However, there are also some obstacles in the adsorption treatment of secondary effluent by activated carbon, and the main problem is the regeneration of activated carbon. During operation, the adsorption capacity of activated carbon will gradually saturate and must be regenerated or replaced. The regeneration method is usually thermal regeneration, which requires three processes: drying, organic matter pyrolysis, and activation. The activation temperature reaches 820 ℃ or above, and the equipment is relatively complex. For systems with small amounts of activated carbon, setting up activated carbon regeneration equipment is not economically feasible. In this case, transporting saturated activated carbon back to the activated carbon plant for regeneration is more economical. Some domestic activated carbon production plants have already carried out this business.

Integrated facilities for medical wastewater treatmentOzone oxidation+biochemical treatment process
For sewage with poor biodegradability, the use of biochemical treatment methods alone cannot achieve high COD treatment effects. Therefore, chemical oxidation+biochemical treatment processes have emerged, in which ozone is mainly used as the oxidant. As ozone is a strong oxidant, it can oxidize many complex organic compounds into simple organic compounds, transforming non biodegradable components into biodegradable components. In this process, ozone is decomposed into oxygen without the production of other harmful substances. For the subsequent biochemical treatment units, some researchers have proposed the biological activated carbon process. On the one hand, activated carbon is used as a microbial carrier to grow biofilms, and on the other hand, activated carbon is used to adsorb difficult to degrade organic substances, further reducing COD in wastewater. The application shows that this process is effective for the deep removal of organic matter in wastewater, but there are also certain problems. Firstly, activated carbon still needs to be regenerated. If not regenerated, saturated activated carbon can only serve as a regular biological carrier; If regeneration is carried out, the biofilm cultured in the previous stage will be destroyed. The second issue is that the secondary effluent treated by sedimentation and filtration still contains 30-40 mg/L COD, and the concentration of ozone added increases accordingly, resulting in increased operating costs. Thirdly, at present, large capacity ozone generators cannot be produced domestically due to high infrastructure investment and complex operation and management.

Solid liquid separation membrane bioreactor is a widely researched and in-depth type of membrane bioreactor in the field of water treatment. It is a water treatment technology that uses membrane separation process to replace the secondary sedimentation tank in traditional activated sludge process. In traditional wastewater biological treatment technology, sludge water separation is completed by gravity in the secondary sedimentation tank, and its separation efficiency depends on the settling performance of activated sludge. The better the settling performance, the higher the sludge water separation efficiency.

The settling property of sludge depends on the operating conditions of the aeration tank, and improving the settling property of sludge requires strict control of the operating conditions of the aeration tank, which limits the applicability of this method. Due to the requirement of solid-liquid separation in the secondary sedimentation tank, the sludge in the aeration tank cannot maintain a high concentration, generally around 1.5-3.5g/L, which limits the biochemical reaction rate.