[Case Study] Sludge Dewatering in Fruit Processing Industry

TECHASE’s specific Multi-plate Screw Press provides a better sludge dewatering solution for wastewater treatment of fruit and vegetable processing industry.

The fruit and vegetable industry typically generates large volumes of effluents and solid waste. The effluents contain high organic loads, cleansing and blanching agents, salt and suspended solids such as fibers and soil particles.

Major wastewater characteristics to be considered for the processing industry of vegetables and fruit are the wide ranges of wastewater volume and the concentrations of organic materials. Wastewater characteristics can be influenced by a number of factors such as the commodity processed, the process unit operations used, the daily-production performance level and the seasonal variation, e.g., growing condition and crop age at harvest.

Ningbo Showco Food CO., LTD (Ningbo Orient Jiuzhou Food Trade &Industry CO.,LTD),which was established in 1996,is a joint-stock company with the production of the canned food and trade as its major business scope.

From November to January, its trade effluent volume is about 800 t/d. In off seasons, it also produces 500 tons of wastewater every day. Its factory would have to be moved if the effluent water from this factory still can’t achieve the local discharging standard.

We proposed a completed scheme to update and improve the former wastewater and waste treatment process system, adding hydraulic grids, an all-in-one flotation system, and Techase Multi-plate Screw Press dewatering system, re-designing the piping system without constructing additional tanks.

The treated water from the updated system has successfully achieved the Class B discharging standard for municipal wastewater.

Huangguan WWTP mainly accepts the trade effluent from the Zhejiang Huangyan First Canned Food Factory which produces canned fruits, juice and fishes. It has to deal with 3,500 ~ 4,000 tons wastewater from this factory.

The biggest problem of this project is the fruits pectin and fish gelatin that is very sticky, large in volume and floating on the wastewater. The existing belt filter press was frequently blocked and consumed large volume of back wash water. The outlet solids still contained a lot of water and very difficult to be transported.

The target of this project is to reduce the COD to less than 300 mg/l and get dewatered solids that will not drop many liquids during transportation. We added a suitable flotation system to remove the solids waste and reduce most of the soluble COD. The COD in the treated water is less than 500 mg/l. Then we replaced the old belt filter press with our Multi-plate Screw Press to dewater the solid waste and excess sludge. The outlet sludge contains much less water and will not drop much water during transportation.