Enhanced biogas yield by thermo-alkali solubilization followed by co-digestion of intestine waste from slaughterhouse with food waste

Abstract

Intestine waste generated from slaughterhouse (IWS) is difficult to degrade in anaerobic process due to the presence of high protein and lipid contents. However, anaerobic co-digestion helps to increase the degradation of IWS by the addition of carbon-rich food waste (FW). To increase the biogas yield, thermo-alkali pretreatment may be more viable method for the anaerobic digestion of protein and lipid rich wastes. In the present study, Thermo-alkali pretreatment of intestine waste from slaughterhouse and food waste alone and mixing of IWS and FW with different ratios (1:1-1:3) on VS basis have been studied. To study the effect of Thermo-alkali pretreatment on solubilization of substrate, the substrate was mixed with alkali solutions (NaOH and KOH) at different concentrations of 1, 2, 3, 4 and 5% solutions. The results revealed that the maximum solubilization was observed to be 94.7% and 90.1% at KOH (1:3 and 5%) and NaOH (1:3 and 5%), respectively. Based on the study, enhancement in biogas yield by 16% (IWS), 11.5% (FW), 12.2% (1:1), 18.11% (1:2) and 22.5% (1:3) in KOH pretreated waste when compared with NaOH pretreated waste.

Abattoir Wastewater Treatment in Anaerobic Co-Digestion with Sugar Press Mud in Batch Reactor for Improved Biogas Yield

“…pH is a vital factor in AD. Therefore, the ideal pH for methanogenesis ranges from 6.5 to 8.2 [56]. In that regard, the current investigation recorded pH values of 8.06 and 5.41 for SHWW and SPM, respectively.…”

“…At the start of acidogenesis, pH is most likely to drop before actually rising as the VFAs degrade to produce methane. In that regard, the accumulation of VFAs can probably cause process instability as it can reflect a kinetic uncoupling between the acidogenesis and acetogenesis phases of the AD process [56]. Herein, the inhibition reported in SPM is most inclined to this attribute.…”

“…In addition, previous findings regarding SPM digestion point to the presence of process inhibitor factors [56]. Indeed, feedstock with a high C/N ratio has a low buffering capacity and generates an excess of VFAs during digestion, resulting in a pH drop [18].…”

“…However, a high VS breakdown in conjunction with a low maximum CH 4 content, on the other hand, denotes an imbalance between acidogenesis and methanogenesis. This is caused by low pH and nutrient deficiency [56].…”

Slaughterhouse and poultry wastes: management practices, feedstocks for renewable energy production, and recovery of value added products

“…In order to aid physical mass transfer, Ware and Power [107] carried out pre-blending of cattle soft offal consisting of intestinal residues, fat, meat trimmings to a particle size of less than 8 mm to aid biodegradation. The results of AD tests in a 900 mL batch AD reactor showed methane yield of 650.9 L/kg VS. Porselvam et al [108] carried out pretreatment (using KOH and NaOH) of intestinal waste prior to the AD process and carried out anaerobic co-digestion with food wastes that resulted in the increase in the methane yield from 119.7-238.1 to 331.5 L/kg VS. In our previous study, extrusion pre-treatment of cattle ruminal contents and blood followed by anaerobic co-digestion with vegetable market wastes, showed an increase in methane production from 273 to 304 L/kg VS.…”