Recearch On The Pilot Test Of Composite Intensified Ecological Filter Bed For The Polluted River

In order to improve the water environment of Liao River and its important tributaries, taking different measurements into consideration by using the idea of water healthy cycle and learning the successful experience from abroad, a new craft that is a combination of constructed intensified biological bed and constructed wetland is applied in the river improvement.The purpose of this experiment that is based on a small pilot study is to provide a theoretical basis and technical support to the subsequent demonstration project. The research mainly consists of four parts as follows: 1. study on starting-up of biofilm growing in the constructed intensified biological bed; 2. study on the oxygen resuming of plants that grow in the constructed intensified biological bed; 3. study on the removal efficiency of pollutants in water; 4. study on the factors which influence the removal efficiency of the constructed intensified biological bed.At the beginning of biofilm growing, the constructed intensified biological bed is vaccinated through activated sludge in the A/O tank at the flow rate of 1m~3As to the study on the oxygen resuming of plants that grow in the constructed intensified biological bed, reoxygenation effect is studied through removal efficiencies, which are different when plants exist or not. /h. After 20days, the biofilm in the constructed intensified biological bed grows into a stable state and maintain stable removal efficiency. The removal rate of COD can be achieved beyond 55%, and the removal rate of ammonia can also be higher than 95%.Controlling the flow rate respectively at 1m~3/h, 2m~3/h, 3m~3/h and also controlling the air-water ratio respectively at 0, 3:1, 5:1, 7:1, it can be concluded that the removal efficiency could be the best when the flow rate is at 1m~3/h and the air-water ratio is at 5:1. Under the best removal efficiency, the hydraulic loading rate stays at 0.25m~3/(m2·h). Judging from the changes of head loss in the constructed intensified biological bed, it is known that the period time for backwash is 120 days. Because filter media of large particles is used in the constructed intensified biological bed, the way of discharging sludge and gas washing are applied in backwash. When the hydraulic loading rate and air-water ratio are controlled at the level according with the best removal efficiency, it is obtained that the combined process can make the removal rate of COD reach 80% and the removal rate of ammonia reach more than 95%. Meanwhile, the removal rate of TN could reach more than 65% and the removal rate of TP can reach 70%.