Anaerobic co-digestion of sewage sludge and molasses

Abstract

Abstract. The efficiency of simultaneous digestion of sewage sludge and by-product of refining sugar beets (molasses) was investigated. The study was conducted for 28 days under mesophilic conditions. 0.5%, 1%, 1.5%, 2% and 3% (m/m) of molasses was added to the mixture of sludge. The result of the study showed that addition of molasses had positive effect the biogas production. The biggest biogas yield was achieved in sample with 0.5% of molasses (95.69 mL/g VS). In this sample biogas production increased by 21% in comparison with reference sample (without molasses). The biggest methane content (73%) was also observed in the sample with 0.5% of molasses. For comparison in reference sample was produced biogas with 70% content of methane. The dose over 0.5% of molasses caused inhibition of fermentation process. The minimal degree (38%) of degradation of organic matter was achieved in reference sample (38.53%) and in sample with 0.5% of molasses (39.71%) but in other samples was in the range of 35.61-36.76 % (from 3% to 1%, respectively). Digestion process have adverse effect on dewatering properties of sludge. Before co-digestion capillary suction time was from 31 s to 55 s, and after process increased from 36 s to 556 s (from 0% to 3% of molasses, respectively).

The Enhancement of Energy Efficiency in a Wastewater Treatment Plant through Sustainable Biogas Use: Case Study from Poland

“…Additionally, the inhibition of long-chain fatty acids (LCFA) may be observed in the FOG presence [56]. However, there are many successful examples of use of such wastes in co-digestion with sewage sludge in terms of biogas and energy production [35,50,56,59,60]. Table 2 presents certain biogas properties with the operational conditions of various organic substances characterized by significant fat content that can be co-digested with sewage sludge.…”

“…The maximum biogas production and methane content in biogas for different organic co-substrates[60].…”

The Use of Biogas From the Anaerobic Digestion of Sewage Sludge to Improve the Energy Balance of Wastewater Treatment Plants

“…The most important substrates for biogas production are organic compounds rich in proteins, fats and hydrocarbons. The fermented The Use of Biogas from the Anaerobic Digestion of Sewage Sludge to Improve… sewage sludge usually contains an appropriate mixture of substances from which biogas can be produced, but sometimes it is necessary to add an external source of biomass [8,13,14,16]. Fig.…”

“…The classic system for producing biogas in a wastewater treatment plant is a solution in which sewage sludge is initially thickened and then pumped to separate/closed anaerobic digester (SAD/CAD), where a mesophilic anaerobic digestion process takes place in the temperature range of 35-39 o C. The holding time is about 20 days, which is the period in which biogas is produced by microorganisms. It is a mixture of gases, mainly methane, carbon dioxide and other gases, whose residual content is water vapor, H 2 S, N 2 , H 2 , O 2 (Table 1) [1,4,13]. A lot of research is being carried out to determine the optimal conditions for the anaerobic digestion of sewage sludge.…”