Ozone Application for Tofu Waste Water Treatment and Its Utilisation for Growth Medium of Microalgae Spirulina sp

¹ Chemical Engineering Department, Faculty of Engineering, Diponegoro University, Indonesia
² Master Program of Environnemental Sciences, Schoolf Postgraduate Studies, Diponegoro University, Indonesia

^* Corresponding author: Hadiyanto@live.undip.ac.id

Abstract

Tofu industries produce waste water containing high organic contents and suspendid solid which is harmful if directly discharged to the environment. This waste can lead to disruption of water quality and lowering the environmental carrying capacity of waters around the tofu industries. Besides, the tofu waste water still contains high nitrogen contents which can be used for microalgae growth. This study was aimed to reduce the pollution load (chemical oxygen demand-COD) of tofue wastewater by using ozone treatments and to utilize nutrients in treated tofu waste water as medium growth of microalgae. The result showed that the reduction of COD by implementation of ozone treatment followed first order kinetic. Under variation of waste concentrations between 10-40%, the degradation rate constant was in the range of 0.00237-0.0149 min^-1. The microalgae was able to grow in the tofue waste medium by the growth rate constants of 0.15-0.29 day^-1. This study concluded that tofu waste was highly potent for microalgae growth.