With goals in determining the effect of diluting the distillery wastewater (DWW) and of varying the amount of DWW and press mud (PM), anaerobic co-digestion study was carried out at mesophilic condition in a 2-L Erlenmeyer flask, with a working volume of 800 mL for Batch 1 and 1500 mL for Batch 2 experiments. For Batch 1, two different ratios of DWW and tap water, with 2:3 and 3:2, were used to assess the effect of dilution on the methane yield, where same volumetric amount of PM was added. For Batch 2, following ratio of PM and DWW were used: a) 1:0, b) 1:1, c) 1:1, d) 2:1, and e) 1:2. All samples had the same amount of inoculum, except that Batch 1 samples had bagasse. The parameters that were assessed after 42 days of digestion were: pH, COD, BOD, TSS, VS, Cu, Ca, Mg, Mn, TOC, TN, and methane yield. For the effect of dilution, a significant difference in the methane yield between samples with higher and lower dilution ratio was seen, and in the first batch, the optimal dilution ratio of DWW and H2O, with 3:2 gave higher methane yield of 78.23% (v/v). Meanwhile, optimal volumetric ratio of DWW and PM from the Batch 2 experiments, with value of 1:2, gave the highest methane yield of 79.43% (v/v).

Organic waste has been discharged into the environment by various industries in a global society. Anaerobic digestion has proven its potential as a waste-to-energy (WTE) technology to produce biogas, which can also replace fossil fuels while accommodating these unwanted wastes. However, there are limitations to anaerobic digestion, such as poor biomethane yield due to limited supply and fluctuations in the composition of the substrates, and an inadequate C/N ratio in the feedstocks. This paper aims to discuss possible methods to overcome the constraints in the process, including co-digestion and immobilization of the substrates via a moving bed biofilm reactor. The parameters discussed in this literature were the following: (1) mode of operation; (2) temperature; (3) type of anaerobic digestion; (4) pre-treatment methods; (5) addition of nutrients; and (6) using plastic carriers. An in-depth study highlighting the role of industries in biogas production toward achieving circularity was also examined. Several studies have shown that co-digestion enhances biogas production more than mono-anaerobic digestion. Notably, using plastic carriers for immobilization can improve the metabolic process due to biofilm formation and serve as a niche for microbial culture. In addition, excessive nutrients can be highly toxic as they can inhibit bacterial activity in the methanogenic phase. This review also presented the techno-economic analysis of utilizing distillery wastewater and press mud from sugarcane industries to produce biogas. Therefore, the findings in this article allow the development of optimization designs for industrial scale based on circular economy to address various organic wastes.

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With goals in determining the effect of diluting the distillery wastewater (DWW) and of varying the amount of DWW and press mud (PM), anaerobic co-digestion study was carried out at mesophilic condition in a 2-L Erlenmeyer flask, with a working volume of 800 mL for Batch 1 and 1500 mL for Batch 2 experiments. For Batch 1, two different ratios of DWW and tap water, with 2:3 and 3:2, were used to assess the effect of dilution on the methane yield, where same volumetric amount of PM was added. For Batch 2, following ratio of PM and DWW were used: a) 1:0, b) 1:1, c) 1:1, d) 2:1, and e) 1:2. All samples had the same amount of inoculum, except that Batch 1 samples had bagasse. The parameters that were assessed after 42 days of digestion were: pH, COD, BOD, TSS, VS, Cu, Ca, Mg, Mn, TOC, TN, and methane yield. For the effect of dilution, a significant difference in the methane yield between samples with higher and lower dilution ratio was seen, and in the first batch, the optimal dilution ratio of DWW and H2O, with 3:2 gave higher methane yield of 78.23% (v/v). Meanwhile, optimal volumetric ratio of DWW and PM from the Batch 2 experiments, with value of 1:2, gave the highest methane yield of 79.43% (v/v).