The main facilities in expressway service area include accommodation (including parking), supermarkets, restaurants, entertainment, gas filling, auto repair and other functions.
In addition to the conventional domestic sewage, the sewage in the service station area also includes some oily sewage and washing sewage generated by gas stations, restaurants and garage. The main pollution factors are petroleum, COD, BOD, SS, etc. The sewage in the service area mainly has the following characteristics:
(1) There are many pollution points and the treatment scale is small. Under normal circumstances, the water consumption of the unilateral service area shall not exceed 10m? /h；
(2) Sewage mainly comes from public toilets and cleaning, with high nitrogen and phosphorus content;
(3) Catering wastewater accounts for a large proportion, and there are oily and lipid pollutants in parking lots, squares, gas stations and car wash wastewater;
(4) The sewage is uneven, and the treatment difficulty is higher than that of typical domestic sewage.
Expressway's affiliated areas, such as toll stations and service areas built earlier, mostly use dry toilets and septic tanks to treat domestic sewage, and there is no professional sewage treatment equipment in the service area. Dry toilets are mostly used in highway construction camps or built service areas in arid or semi-arid areas, and septic tanks are mostly used in flush toilets with certain sanitary requirements.
Dry toilets and septic tanks have low investment and convenient management, which are all environmental protection measures according to local conditions, but their effluent and sediments are generally difficult to meet the requirements of relevant sewage discharge standards. Due to the small amount of domestic sewage discharged by facilities along expressway, generally small domestic sewage processors can meet the requirements, and there is no specially designed sewage treatment equipment in the service area.
Therefore, many domestic expressway began to try to use the integrated domestic sewage processor to treat the domestic sewage in the service area. It not only saves valuable highway land, but also meets the relevant environmental protection requirements. Buried integrated domestic sewage treatment facilities have many advantages, and gradually become the first choice for domestic sewage treatment in expressway service area.
Characteristics of sewage volume in service area:
The sewage volume in expressway service area varies greatly in seasons, and the sewage volume in summer may be 5-6 times or even higher than that in winter. Due to the influence of traffic flow, the amount of sewage not only varies greatly in different seasons, but also fluctuates greatly at different times of the day.
Therefore, the sewage discharge in the service area fluctuates greatly. However, at present, the sewage treatment equipment in the service area generally chooses finalized products, which cannot be designed on site according to the actual situation, and the design capacity is quite different from the actual sewage volume, which often leads to insufficient treatment capacity or wasted investment.
The obvious shortcomings of sewage treatment technology in expressway service area in China are that it can't cope with the dynamic change of sewage volume, consumes a lot of electricity, has high operation and management costs, and the equipment is easily damaged. Therefore, the sewage treatment equipment with low capital construction cost, good operation effect and convenient management is the most needed in the service area at present.