The gelatinous industry is the most polluting process where huge quantities of chemicals (i.e., NaOH, HCl, Ca2+) are utilized in the manufacturing processes. Considerable wastewater quantities are produced and contain a big portion of protein. Discharge of such wastewater into sewerage network and/or water streams causes severe pollution problems and represents a pollution source of drinking water as well. Simultaneous treatment and energy production from gelatinous wastewater (GW) is a promising approach due to saving energy, chemicals, and less excess sludge. Fortunately, the biodegradability (BOD:COD ratio) of GW exceeds 0.6 and is rich with calcium ions; it thereby represents a promising substrate for biofuel production (H2 and CH4) using anaerobes. This chapter describes anaerobic technologies for energy production from the GW industry. Anaerobic digestion of protein-rich wastewater often results in the formation of scum and causes sludge washout, which has a negative effect on reactor performance. This problem has significantly hindered the application of the anaerobic process to the treatment of wastewaters from gelatin industries. In addition, proteins are degraded more slowly than carbohydrates. Carbohydrate presence in GW lowers the protein degradation rate. Those problems could be overcome by intentional discharge of the excess sludge from anaerobic digester and use of a two-stage system for treatment of GW.
Clean Energy and Resources Recovery. Biomass Waste Based Biorefineries, Volume 1, 2021, Pages 145-154,