Domestic wastewater at the building includes wastewater generated from daily activities such as bathing, eating, hygiene, washing, etc. The characteristics of wastewater in this building are black when not decomposing, contains many suspended solids, uneaten food, grease and waste impurities, etc. Due to the composition of wastewater, this type of wastewater often stinks due to the decomposition process of impurities. organic matter.
Although inorganic substances such as dirt, sandy soil do not cause much impact, they affect the wastewater treatment process of the system. In addition, microorganisms are harmful to human health, and the environment is abundant in this waste water, posing a risk of spreading diseases to the community, seriously affecting lives and umbrellas. environmental pollution.
Polluted organic and inorganic substances are shown in the following table.
|Pollution index||Unit||Typical value range of WW||QCVN14:2008/BTNMT – Column B|
|1. pH||–||5 – 9|
|2. BOD5 (20oC)||mg/l||110 – 400||50|
|3. Total suspended solids (TSS)||mg/l||100 – 350||100|
|4. Total dissolved solids||mg/l||850 – 1800||1000|
|5. Sunfua (theo H2S)||mg/l||–||4.0|
|6. Amoni (N)||mg/l||25 – 45||10|
|7. Nitrat (NO3–) (N)||mg/l||20 – 85||50|
|8. Animal and vegetable fats and oils||mg/l||50 – 200||20|
|9. Total surfactants||mg/l||–||10|
|10. Phosphat (PO43-)||mg/l||8 – 20||10|
|11. C olifoms||PMN/ 100ml||10000 – 15000||5000|
Proposed Technology Diagram
Explanatory process technology
Wastewater from building activities is pre-treated before being put into collection pits to remove grease, large-sized garbage, … to avoid hitting, damaging the pump and at the same time protecting Pipeline avoids clogging during processing. At the receiving tank, there are 2 submersible pumps controlled by the buoy system with 2 levels of water (shallow, full pump). Two rotating pumps are responsible for transferring wastewater to the regulating tank.
Waste water from the collection pit is pumped to the regulating tank. This regulating tank has the following main functions: Regulating flow, stabilizing the concentration of pollutants in wastewater, avoiding shocking load for rear treatment facilities (due to unstable water discharge mode specified) through a uniform mixing process throughout the tank volume. Reduce the volume of the rear treatment facilities, thereby reducing investment costs. Ensuring the system always operates stably.
Adhesive aerobic biological tanks
Waste water from the regulating tank is pumped to the sticky aerobic biological tank. Here, the tank uses the substrates for microorganisms to stick to to grow and develop. Microorganisms capable of decomposing organic compounds will stick and grow on the surface of the material, aerobic microorganisms will convert organic substances in wastewater to develop into biomass. In the case of treatment of organic compounds in wastewater, there is also the process of nitrification and denitrate in the aerobic biological tank, which helps remove nitrogen and phosphorus compounds in wastewater. Microorganisms adhering to the surface of the material include 3 types: the outer layer is anaerobic, the next one is anaerobic and the anaerobic zone is in the region. In domestic wastewater, nitrogen mainly exists in the form of ammonia and organic nitrogen. Because aerobic microorganisms will convert nitrogen compounds into the form of nitrite, nitrate. Continuing anaerobic and anaerobic microorganisms will use organic compounds in wastewater as oxidants to reduce nitrate, nitrite to N2 form.
Biological sedimentation tanks
Wastewater after biological treatment process contains lots of microorganisms. Therefore, it is necessary to separate the mud from the settling tank before going through the next treatment process. Sediment tanks are designed to settle microorganisms mud by gravity process. The tank is divided into 3 parts: clear water, sediment, mud. Water is put into the central pipe and from there evenly distributed throughout the tank. Under the force of gravity and the barrier of the microorganism mud settling to the bottom, clear water moves upwards. The clear water will be collected through the overflow system, which continues to flow to the disinfection tank. And the sediment will be divided into two lines as follows: Circulation flow back to aerobic biological tank adhesion to provide microorganisms for denitrification and maintain biomass concentration in aerobic tanks to help the process achieve high efficiency. Excess sludge flows to the sludge tank.
The disinfection tank is responsible for disinfecting wastewater before being pumped to the filter tank. Here, chemicals are added to kill the microorganisms in the sewage. The process of destroying microorganisms occurs in 2 stages. The disinfectant first diffuses through the cell wall of the microorganism, then reacts with the enzyme inside the cell and disrupts the metabolism that leads to the destruction of the microbial cell.
Sludge storage tank:
The residual sludge from biological sedimentation tanks with high humidity will be transferred to sludge tanks to stabilize the volume. Mud tank is responsible for storing and stabilizing sludge for the system, the sludge here will be collected and treated periodically.
Some actual works
- Wastewater treatment station of high-class apartment SHP Plaza Hai Phong
- WWTP of My Dinh Pearl Project, Nam Tu Liem District, Hanoi
- Wastewater treatment system for daily life Mixed-use office, commercial service, residential area No. 3 Luong Yen
- Waste water treatment station of Melinh Plaza Thanh Hoa Commercial Complex
- WWTP of D’.El Dorado Phu Thuong Project
- WWTPs of the Great Dragon Hotel