Highway service area facilities include supermarkets, toilets, accommodation, restaurants, gas stations and so on. Therefore, the sewage in expressway service area is generally composed of domestic sewage, restaurant sewage, car wash, gas station sewage and so on. Domestic sewage and gas station cleaning sewage are the main types of sewage. The quality of sewage is similar to that of typical domestic sewage and car washing sewage. The sewage discharged from restaurants, large public toilets and hotels in expressway service area is relatively more, especially from toilets and showers. As a result, the concentration of ammonia nitrogen and S S in the sewage of service area is high. The pollutants in the sewage of car washing are mainly sediment particles and petroleum. The drainage of vehicle filling station and maintenance station is mainly petroleum. Highway service area discharges less waste water from refueling, car washing and car repair, which is usually mixed with domestic sewage through oil separating pool pretreatment and subsequent treatment.
Service area sewage has its own characteristics: high ammonia nitrogen content, high color, high chemical oxygen demand, high phosphorus, heavy metals, oil pollution and other pollutants, complex water quality, large fluctuations in water volume. The distinct difference between sewage in expressway service area and domestic sewage is the unstable water quality and quantity. This has a lot to do with traffic. There are few permanent residents in the service area. The main reason is the sewage generated by passengers'parking. The traffic of vehicles is very random. Therefore, the amount of water that occurs also has great fluctuation, and the amount of water may be different every hour, every day and every month.
Based on many years of technical reserve and a large number of on-site investigations, our company has developed a new type of integrated sewage treatment equipment for expressway service area sewage treatment, one-stop solution to the sewage problem in expressway service area.
Picture of actual delivery
1. Buried below the ground, the ground above the equipment can be used as greening or other land, without building, heating and heat preservation.
2. Push-flow biological contact oxidation is used in the secondary biological contact oxidation treatment process, and its treatment effect is better than that of the fully mixed or two-stage series biological contact oxidation tank. Compared with activated sludge tank, it has smaller volume, stronger adaptability to water quality, better impact load resistance, stable effluent quality and no sludge bulking. A new type of combined three-dimensional filler is used in the pond, which has large specific surface area, easy to film-forming and defilm by microorganisms. Under the same organic loading conditions, the removal rate of organic matter is high and the energy consumption is low.
3. Biological contact oxidation method is used in biochemical pond. The volume load of filler is relatively low, microorganisms are in their own oxidation stage, and the sludge yield is low. It only takes three months (90 days) to discharge sludge (suction or dewatering by dung truck to make sludge cake for transportation).
4. The deodorization method of the buried domestic sewage treatment equipment uses conventional high-altitude exhaust gas and soil deodorization measures.
5. The whole equipment processing system is equipped with automatic electrical control system and equipment failure alarm system. It runs safely and reliably. Normally, it does not need special management, and only needs timely maintenance and maintenance of the equipment.
★ Working Principle:
Because the sewage of expressway service area contains more suspended impurities, pathogenic microorganisms and other pollutants, it is necessary to remove these pollutants by physicochemical process as early as possible. Otherwise, it will affect the operation and management of the whole processing system. Therefore, the scheme plans to set up grilles before sewage enters the biochemical treatment system to remove suspended solids in water.
Because the CODCR content of sewage is low and the biochemical effect is good, in order to reduce investment, reduce operation cost and enhance the impact load resistance of the system, this scheme adopts the "anaerobic + aerobic" treatment method to treat sewage biochemically.
The sewage first passes through the grille trough to remove the impurities such as suspended substances in the water, so as to prevent the blockage of the follow-up treatment sheet, resulting in water silting and affecting the operation of the system. The sewage filtered by grille flows into the regulating tank, which serves as a structure for regulating and homogenizing the amount of sewage water. Because the discharge of sewage during the day and night has the characteristics of uneven time interval and large time-varying coefficient. In order to make the follow-up treatment system run in a balanced way and minimize the impact of the impact load of sewage to achieve the desired treatment effect, it is necessary to set up a regulating tank to regulate and homogenize the amount of sewage water, so that the lifting pump of the regulating tank can always supply water to the follow-up treatment system according to the average amount of treated water. Statistics show that the effective volume of the regulating tank is calculated according to the average hourly treatment capacity of 6-10 times. Two sewage lifting pumps are installed at the end of the pool for lifting water to an integrated sewage treatment equipment, one for one. The operation of lifting pump is controlled by liquid level float ball. The pump starts automatically when the water level in the regulating pool is high and stops automatically when the water level is low.
The effluent from the regulating pond flows into the high efficiency anaerobic pond. The anaerobic hydrolysis acidification biological treatment of wastewater is a treatment method that uses the degradation of anaerobic microorganisms to purify organic substances in wastewater under anaerobic or anoxic conditions. Under anaerobic conditions, the anaerobic bacteria in sewage decompose carbohydrates, proteins, fats and other organic substances into organic acids, and then under the action of methanogens, further ferment to form methane, carbon dioxide and hydrogen, so that the sewage can be purified. After hydrolysis acidification treatment, the macromolecule refractory organic matter in water can be transformed into small molecule degradable organic matter, thus improving the treatment effect of subsequent aerobic treatment unit. Hydrolysis acidification process can greatly shorten the time required for aerobic biochemistry, and the treated water quality is better, which not only saves investment, saves operation costs, but also improves environmental benefits.
The effluent from anaerobic tank flows into a new contact oxidation unit. Biological filler is a combination filler in fixed bed. Fillers are used as attachment carriers for microorganisms. Biology is evenly distributed on the biological filler, which avoids the phenomenon of uneven distribution of microorganisms. At the same time, the biofilm adheres to the surface of the filler and does not flow with the water. Because the biofilm is directly agitated by the updraft, it is constantly updated, thus improving the purification effect. The high efficiency leachate process has the advantages of short treatment time, small volume, good purification effect, good and stable effluent quality, no reflux, no expansion of sludge, and low power consumption.
Its main characteristics are:
(1) High volume load and strong shock resistance;
(2) It has the advantages of membrane technology and less excess sludge.
(3) Activated sludge has the advantages of high biological activity and short sludge age, supplemented by mechanical equipment for oxygen supply.
(4) It can decompose other refractory substances in biological treatment.
(5) Easy to manage, eliminating sludge floating and bulking and other drawbacks.
The treated sewage from the contact oxidation unit is treated by sedimentation tank, filter and disinfection tank and discharged to the standard.
★ Implementation criteria:
Discharge Standards for Pollutants from Urban Sewage Treatment Plants (GB 18918-2002)
Pictures taken on construction site