Flat MBR Used for Hospital Wastewater Treatment and Reuse

According to the amount of wastewater and water quality of a psychiatric hospital in a province, the wastewater is treated effectively with MBR flat membrane and corresponding process. After treatment, the wastewater meets the reuse water standard. The cost of the project design and operation is approximately: 0.79 yuan/m3.

1 Project Overview

A psychiatric hospital is a specialized hospital for mental and neurological diseases. It is also a famous large-scale provincial grade A hospital in the country. The actual wastewater discharge of the hospital's existing project is 400m3/d. The wastewater discharge of the project under construction is 120m3/d. The expansion project is added by 37.2m3/d. After the completion of the expansion project, the hospital has a total of 557.2m3/d. The mental hospital is now Sewage treatment station sewage treatment scale is 500m3 / d, the existing treatment scale and technology can not meet the medical wastewater treatment requirements, according to hospital planning, plans to build a new medical wastewater treatment station to deal with the hospital medical wastewater.

Considering the operation and management factors in the actual operation, the treatment scale of general wastewater facilities is not less than 1.2 times of the actual water volume. Therefore, the project design scale is 700m3/d. The designed effluent water quality meets the urban miscellaneous water quality standard and at the same time meets the pollutant discharge of medical institutions. standard.

2 Design basic parameters

The sewage mainly comes from the domestic sewage produced by the psychiatric hospital. See Table 1 below for the quality of the influent water.


3 Process Flow and Features

3.1 Introduction to Process Flow


The object of this project is hospital sewage. The hospital is a psychiatric hospital. Compared with other comprehensive hospital wastewater, the water quality is low in concentration, there is less virus in the water, biodegradability is better, and water quality is not changed much. Similar to domestic sewage.

Conventional hospital sewage treatment processes can be divided into activated sludge and biofilm processes. Activated sludge activated sludge method has a long incubation time, complex operation and operation management, strict requirements for operators, and must have certain professional capabilities. It is generally used for medium or high concentrations of water, but also can be applied to water with a certain degree of fluctuation, biofilm method, due to the growth of fillers or other substrates for biofilm growth, cultivation time is faster, the winter is generally 2 to 3 Weeks and summers are generally 1 to 2 weeks, which can be implemented more rigorously and can be operated stably after system debugging. The biofilm method has poor anti-shock load and is generally used for low-concentration sewage water with small water volume and small fluctuations in water quality and water volume. Moreover, the above processes require a secondary settling tank, and the effluent of the secondary settling tank cannot reach the design index. Therefore, advanced treatment is required, and the system operation department is stable, and the effluent water quality bacteriological index exceeds the standard. In order to reach the goal, the sewage treatment adopts a new sewage treatment process - membrane bioreactor process (MBR process).

3.2 MBR process features

(1) Effluent water quality and stability: Due to the efficient separation of MBR flat membranes, complete separation of hydraulic retention time (HRT) and sludge retention time (SRT) is achieved, the treated water is clear, suspended solids are close to zero, bacteria and viruses Removed by large-scale interception, the effluent quality is better than the Class A emission standard for urban sewage, and meet the city's miscellaneous water quality, and can be directly reused as medium water.

At the same time, MBR flat membrane separation also allows microorganisms to be completely shut off in the bioreactor, ensuring that the microbial concentration in the system is maintained at a high level, which not only improves the overall efficiency of the reactor in removing pollutants, but also ensures high quality The water quality of the effluent, while the reactor is strong against the impact load, can obtain stable quality effluent water quality.

(2) Less excess sludge production: The MBR flat membrane process can be operated under high volume load and high sludge load. Theoretically, zero discharge of organic sludge can be achieved, and the sludge management cost can be greatly reduced.

(3) Small footprint, not limited by setting occasions: Bioreactors can maintain microbial counts as high as tens of thousands of mg/L, with high volume loading of processing equipment, high processing efficiency, and significant savings in floor space; the MBR The flat membrane process is simple, compact and saves space. It is not limited by the installation site and is suitable for any occasion. The small amount of water can be made into an integrated device, which can be buried underground, placed on the ground, or semi-buried.

(4) Removal of ammonia nitrogen and hard-to-degrade organics: The MBR flat membrane process completely shuts off microorganisms in the bioreactor, which is beneficial to the retention and growth of microorganisms with long growth cycles. For example, nitrifying bacteria increase the concentration of bacteria in the system and increase the nitrification efficiency. At the same time, the hydraulic retention time of some hard-degradable organic pollutants in the system is prolonged, which is conducive to improving the degradation efficiency of refractory organics.

(5) Convenient operation and management, easy to implement automatic control: The MBR flat membrane process adopts PLC control, which can realize remote monitoring, and the operation control is more flexible and stable.

(6) It is easy to reform from the traditional process: The MBR flat membrane process can be used as an advanced treatment unit for traditional wastewater and hospital wastewater treatment processes, in the upgrading and reconstruction of municipal wastewater, hospital wastewater, and other industries, in-depth treatment, and reuse of water Has a broad application prospects.

4 Operational cost analysis

Installation power of the equipment in this project: 97.03kW, operating power: 59.43kW; actual power consumption: 35.658Kw (permissible coefficient: 0.60) The electricity fee is calculated at 0.5 yuan/kWh, and the electricity cost per m3 wastewater treatment and reuse is 0.61 yuan. /m3; The system has two maintenance staff. Salaries are calculated at 24,000 yuan per person per year. The cost per m3 of sewage treatment is 0.18 yuan/m3, and the operating and maintenance cost per ton of sewage is 0.79 yuan/m3.

5 Concluding remarks

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