Abstract
The tofu industry is generally a household-scale industry so that the efficiency of water used and wastewater treatment are mistreated. Wastewater from tofu industry is very hazardous when discharged directly into the aquatic environment as it contains high organic pollutants which is indicated by high concentrations of BOD (biological oxygen demand), COD (chemical oxygen demand), TSS (total suspended solid), TDS (total dissolved solid) and turbidity. The optimization of wastewater treatment process is needed to meet the quality standards set by the government and also needed to obtain more effective and efficient effluent treatment. The aim of this study is to evaluate the performance of combination coagulation-flocculation and ultrafiltration processes for tofu industry wastewater treatment. The process of pretreatment coagulation and flocculation using poly aluminum chloride (PAC) was conducted to extend the life of the ultrafiltration membrane and improve the performance of ultrafiltration membrane separation. The experimental results showed that TSS and turbidity decreased with precipitation time whereas COD did not significantly change. TDS after coagulation-flocculation has increased due to the addition of PAC. The TSS, TDS, COD and turbidity of wastewater were drastically reduced after experiencing ultrafiltration process. After the ultrafiltration process, the TSS, Turbidity, COD and TDS rejection were 98.8%, 98.1%, 71.0% and 50.6%, respectively.
Highlights
Tofu is very popular food in Asian country especially in Japan and Indonesia, and is getting popular in European countries due to the associated health benefits and its suitable price [1]
The solid waste of tofu factories is generally used as animal feed, while the liquid waste can partly be utilized for the clumping of tofu in subsequent production
The high of COD value is most probably due to ion Na+ in the produced water that cannot be separated by the ultrafiltration process
Summary
Tofu is very popular food in Asian country especially in Japan and Indonesia, and is getting popular in European countries due to the associated health benefits and its suitable price [1]. The tofu factory is a small scale household, so the efficiency of the use of water resources and soybean is still low and the level of waste production is very high. Tofu wastewater is divided into two types based on physical appearance, namely solid waste and liquid waste. The solid waste of tofu factories is generally used as animal feed, while the liquid waste can partly be utilized for the clumping of tofu in subsequent production. Because the volume of wastewater is very large, generally cannot be reused entirely so that it is discharged into the surrounding waters environment. Wastewater of tofu factories contains high organic compounds. Conventional or chemically processed wastewater treatment is difficult as the wastewater contains suspended solids, COD and high concentrations of oil [3]
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