General large and medium-sized sewage treatment plants are used mechanical dehydration. There are many kinds of dewatering machine, according to dewatering principle can be divided into vacuum filtration dehydration, pressure filtration dehydration and centrifugal dehydration three categories.
This paper introduces the working principle of the filter press (including Belt filter press and plate-frame filter press) and centrifugal dewatering machine which are used frequently in domestic wastewater treatment plant, the problems to be considered when selecting equipment and the maintenance operation cost.
1, Belt filter Press is affected by the fluctuation of sludge load, but also has the low water content and stable start-up consumption, management control is relatively simple, the quality requirements of the operators are not high. At the same time, since the belt filter dewatering machine into the domestic earlier, there are a considerable number of manufacturers can produce this equipment. In the construction decision-making of sewage treatment project, the belt filter press can be used to reduce the project investment.
At present, the domestic new sewage treatment plant mostly using belt filter dewatering machine, such as Beijing Gaobeidian Sewage Treatment plant, a five dehydration machine is all belt filter dewatering machine, filter belt, roll pressure tube put into operation since the situation is good, so in the two period equipment selection is still selected this model.
2, the general plate-and-frame filter press and other types of dewatering machine compared to the mud cake containing the highest solid rate, up to 35%, if from the reduction of sludge stacking factor considerations, plate-frame filter press should be the preferred solution. The way the filter plate is moved. Requirements can be hydraulic one pneumatic device fully automatic or semi-automatic completion, the operation is inconvenient, filter cloth oscillation device, so that the cake easy to fall off. Compared with other types of dewatering machine, the biggest disadvantage of plate-and-frame filter press is that it occupies a large area. Taking Beijing Gaobeidian Sewage treatment Plant, the first phase of the belt filter press and Anshan industrial sewage treatment plant used by the plate-frame filter press as an example to compare: Gaobeidian sewage Treatment plant sewage capacity of 500,000 t/d, sludge production 1852.5m3/d, dry matter 92.63t/d, The use of five German KLEIN-KS30 type belt filter press, each filter press base covers an area of only 2750*3500mm, Anshan wastewater Treatment Plant for the 22t/d, dry matter 275t/d, using six plate frame filter press, each filter machine base covers an area of up to 2400* 12000mm, at the same time, due to the plate-frame filter press for intermittent operation, low efficiency, poor operating environment, there are two of pollution, domestic large-scale sewage plant has been rarely used.