A Pilot-experimental Study On The Application Of Pelleting Fluidized Bed Concentration Technology To Water Plant Wastewater Treatment

High organic matter and algae content characterized the wastewater of reservoir-sourced water plant in south China, the sludge conditioning and dewatering was so taxing a job. The traditional treatment process of this kind of wasterwater means expensive investment, high cost of running, large area of occupation, and poor efficiency of treatment. The previous experimental result has indicated that pelleting fluidized bed technology (PFBT) was a practical and feasible unified process to treat the wastewater. By using PFBT, the cost was declined dramatically, the sludge dewaterbility was improved markedly, whereas the construction area was minished obviously.In this paper, based on the previous experiment, by taking the Meilin water plant wastewater treatment as the object, PFBT was applied to concentrate the wastewater with a scale of 1.0~2.5m3/h. Experimental results showed that:(1) Under the pilot-experimental condition, taking the cation ployacrylamide(PAM) as flocculant, the minimum dosage was 3.6-4.2‰, and 5rpm was the optimal stirring speed of blender; Under continuous experimental condition, the maximum water flow rate of the PFBT was in negative proportion to the TS of the raw sludge, water flow rate in the pelleting fluidized bed (PFB) could reach 49.6cm/min when the TS of the raw sludge was 6870mg/L, while the corresponding maxiumum water flow rate was decreased to 37.7cm/min when the TS of the raw sludge ascended to 11158mg/L. Under the same experimental condition, with the lime dosage of 500mg/L, the PAM dosage could be saved to 2.8~3.5‰, and the maximum water flow rate could be enhanced from 38~50cm/min to 42-57 cm/min.(2) Compared with the conventional gravity-concentration process, by using PFBT, the flocculant dosage could be saved dramatically. Under the conventional process, the PAM dosage is 5~7‰, accompanied with lime dosage of 1600mg/L. The experiment indicated thatthe consumed dosage of PAM was just 25~40% of conventional process without lime consume; When the lime was used following the PAM as flocculant, the PAM consume could be a half of the conventional process, and the lime dosage was saved about 70%.(3) Using the PFBT, the sludge sendimentability could be improved markedly within a short time. The sludge particle sendimental rate of conventional process is 0.0167mm/s, while the same index of PFBT is 5~20 mm/s.(4) Using the PFBT, the solid concentration of the sludge could be reduced significantly within a short time. Under the traditional process, the conditioning couldn't contribut to the sludge concentration, and the solid concentration was about 1%; With the fit PAM dosage, the sludge concentration would be 3~5% after the PFBT process.(5) The centrifuge was choosen as the following dewatering device.(6) Compared with traditional process, by using the PFBT process, the running cost could be economized about 51%, the investment was reduced to 26%, and the occupied area was just 24% of the traditional process.