Beijing Gaobeidian Wastewater Treatment Plant

Beijing Municipal Research Institute of Environmental Protection recently issued a survey report entitled "Technical report on typical wastewater treatment in North China". The research team carried out the investigation of wastewater treatment technologies in Beijing and Hebei provinces that may be suitable for adoption in Africa.

The investigation consists of field research and information provided by company, focusing on the wastewater treatment process, investment costs, operating costs, treatment capacity, occupation area, inflow conditions and water quality and other aspects.

Gaobeidian wastewater treatment plant which is located in Beijing Gaobeidian Township, Chaoyang District, is the largest secondary wastewater treatment plant of 16 municipal wastewater treatment plants planned in Beijing with a total investment of 1.644 billion RMB and a total area of 68 hectares. The second phase of construction was finished in 1999 and the total treatment capacity reached 1 million m3/d, which accounts for about 40% of current total wastewater in Beijing.

The plant is responsible for wastewater collection and treatment in the downtown area and the eastern industrial zone which has a total area of 9661 hectares and a population of 2.4 million. Gaobeidian wastewater treatment plant takes advantage of conventional secondary biological treatment (A2/O) with operating cost of about 0.2 to 0.25 RMB/ton. Effluent water quality as shown in Table 1.1 achieves the GB18918-2002 standard B , and part of the treated water is discharged to Tonghuihe, which plays an important role for improving the water quality of Tonghuihe. Another part of about 470,000 m3/d is treated with reclaimed water treatment process "denitrifying biofilter + UF + Ozone plus disinfection" with operating cost of 1.48 RMB/ton and energy consumption is about 0.4 to 0.5 kWh of electricity per ton of water. 10,000 cubic meters per day of reclaimed water is provided to Huaneng and Shijingshan as plant and green watering and to Gaojin Thermal Power Plant as industrial cooling water. 300,000 cubic meters of reclaimed water is also provided to Beijing No.6 water plant and Gaobeidian Lake as industrial cooling water (4 RMB/ton) and as urban green irrigation water (1 RMB/ ton).

The water quality standard for the discharge of the reclaimed water and the various uses is as shown in table 1.2. Excess sludge is treated with a two-stage anaerobic digestion process operating at medium temperature. Biogas generated during digestion process can produce electricity of more than 10 million kWh, equivalent to 5,000 households electricity consumption per year, which can meet the demand of 20% electricity consumption in the plant. After dehydration, sludge digested with moisture content of 60% to 65% can be used as an agricultural fertilizer and green sources.

Table 1.1  Effluent water quality in Gaobeidian WWTP ( unit is mg/L except for chromaticity)

Table 1.2 water discharge standard of Gaobeidian reclaimed water treatment plant (mg/L)

(GB/T 18921-2002&GB3838-2002)

Parameter	Aesthetic environment use			Entertainment environment use			Environmental quality standards for surface water (Class IV)
	River	Lake	Landscape	River	Lake	Landscape
DO	1.5			2			3
BOD5	10	6		6			6
SS	20	10		No demand			10
TN	15						1.5
NH3-N	5						1.5
TP	1.0	0.5		1.0	0.5		0.3（lake and reservoir 0.1）