Optimization of Temperature, pH, and Substrate Concentration for Biogas Production from Tofu Wastewater
Yusron Sugiarto*, Rahma Auliya Hidayah, Darmanto, Yusuf Wibisono, Wahyunanto Agung N., Ni Matul Izza, Elya Mufidah, Inggit Kresna Maharsih, and Angky Wahyu Putranto

Department of Biosystem Engineering, Faculty of Agricultural Technology, Universitas Brawijaya, Jl. Veteran, Malang 65145, Indonesia

*Email: yusronsugiarto[at]ub.ac.id

Abstract

The increasing energy needs in Indonesia demand the development of alternative energy that is sustainable and environmentally friendly. One potential solution is the production of biogas from organic waste, such as tofu waste. Tofu waste has potential in biogas production because it has a fairly high content of organic matter and theoretically has a methane potential of 61.5%. This study aimed to optimize key parameters (temperature, pH, and substrate concentration) on methane yield using a two-phase anaerobic digestion system. Optimization was carried out through Response Surface Methodology (RSM) with a Box-Behnken Design (BBD) at the laboratory scale. Experimental treatments included temperature variations (30, 40, and 50 C), pH levels (6, 7, and 8), and substrate concentrations (16.67, 33.34, and 50 g/L). The responses evaluated were methane production rate and cumulative methane yield. Results indicated that the optimal condition was achieved at 30.2 C, pH 8, and 16.67 g/L substrate concentration, resulting in a methane production rate of 99.44 ml/L/day and a cumulative methane yield of 945.42 ml/L, with a desirability index of 0.897. These findings highlight the potential of tofu waste as a sustainable feedstock for renewable energy generation.

Keywords: Anaerobic digestion- Biogas- Box-Behnken design- Response surface methodology- Tofu waste

Topic: Waste and environmental management and engineering