Abstract
Chemical Oxygen Demand (COD) is one of pollution parameter that have to be reduced so the wastewater may not harm the environment. Tofu wastewater is one of the organic wastewater that have high concentration of COD. The level of COD in untreated tofu wastewater outnumbered 8000 mg/L. This parameter could be lowered by plasma electrolysis that produced radical species to degrade pollutants in the wastewater. Three variations had been done in this study, such as: the addition of Fe2+ ion as a catalyst, the voltage, and the depth of anode. It was shown that addition of 60 mg/L of Fe2+ ion in plasma electrolysis could degrade COD in tofu wastewater to 73%. The effect of the voltage also had been studied. By using the voltage at 750 V could discard COD as much as 85%. The last variation that was conducted in this study is the effect of the depth of anode in plasma electrolysis. The result showed that 73% of COD in tofu wastewater could be reduced by using the depth of anode 2 cm. All of these results showed that plasma electrolysis is a potential method to degrade pollution parameter, especially COD in tofu wastewater.
Highlights
Most people in Indonesia eat tofu as a daily food because of its nutrition
Tofu waste is divided into three categories: the solid waste or so-called tofu dregs, the wastewater, and the gaseous waste that is generated from fumes cooking process and foul odor from biodegradable waste
Chemical Oxygen Demand (COD) in untreated tofu wastewater outnumbers 8000 mg/L. This wastewater is classified as the hazardous waste for the environment, as a consequence, the state minister of environment in Indonesia confirmed that the quality standar of COD in tofu wastewater has to be below 300 mg/L
Summary
Most people in Indonesia eat tofu as a daily food because of its nutrition. To meet the needs, many tofu plants were established. Tofu wastewater is usually produced by immersing, washing, clumping, and pressing processes It contains many organic materials and make the level of chemical oxygen demand increased. The method that we used to treat the wastewater in this study was plasma electrolysis. It is confirmed that this electrolysis occurred with hydrogen gas formation at the cathode and oxygen gas formation at the anode [6]. This process will form energetic species, with the hydroxyl radical as the strongest one [5]. Plasma electrolysis had been studied as an effective method to treat wastewater [7,8]. In this paper, we would focus on the effectiveness of those three factors to reduce COD in tofu wastewater
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