Effect of humic acid in leachate on specific methanogenic activity of anaerobic granular sludge

Abstract

In order to find out the effects of humic acid (HA) in anaerobic-treated landfill leachate on granular sludge, the anaerobic biodegradability of HA as well as the influences of HA on the total cumulative methane production, the anaerobic methanization process and the specific methanogenic activity (SMA) of granular sludge are studied in this paper. Experimental results show that as a non-biodegradable organic pollutant, HA is also difficult to be decomposed by microbes in the anaerobic reaction process. Presence of HA and changes in the concentration have no significant influences on the total cumulative methane production and the anaerobic methanization process of granular sludge. Besides, the total cumulative methane production cannot reflect the inhibition of toxics on the methanogenic activity of granular sludge on the premise of sufficient reaction time. Results also show that HA plays a promoting role on SMA of granular sludge. Without buffering agent the SMA value increased by 19.2% on average due to the buffering and regulating ability of HA, while with buffering agent the SMA value increased by 5.4% on average due to the retaining effect of HA on the morphology of the sludge particles. However, in the presence of leachate the SMA value decreased by 27.6% on average, because the toxic effect of the toxics in the leachate on granular sludge is much larger than the promoting effect of HA.

A New Approach to Assess the Effect of Various Humic Compounds on the Metabolic Activity of Cells Participating in Methanogenesis

“…In still another investigation, an analysis of the specific methanogenic activity of granular anaerobic sludge in wastewater containing sodium humate at a concentration of up to 2 g/L showed an increase of this parameter by 19.2% [13]. These results demonstrated that HCs can enhance the metabolic activity of granular sludge.…”

“…It was found that the presence of sodium humate in concentrations up to 2 g/L does not significantly affect the accumulation of CH 4 and even has a certain stimulating effect on the methanogenic activity of anaerobic sludge, which on average is increased by 19% as a result of the buffering and regulating ability of sodium humate [13]. In another study of several methanogenic consortia, partial inhibition of methanogenesis was observed only at an HC concentration of 10 g/L and complete inhibition was shown at 20 g/L HC [14].…”

Effects of different N-acyl-serine lactone signaling molecules on the performance of anaerobic granular sludge

“… 15 The SMA value is calculated by cumulative methane production, and then fitted by one-dimensional linear model. 16 The SMA value was calculated using formula (1) : 17 where k denotes the slope of the fitted line, mL h −1 ; VSS denotes the average concentration of sludge biomass in the culture bottle, mg L −1 ; and V denotes the volume of the mixture, L.…”