Enhancing anaerobic digestion of dairy and swine wastewater by adding trace elements: evaluation in batch and continuous experiments

Abstract

Trace elements play a critical role for microbial activity in anaerobic digestion (AD) but their effects were probably overestimated in batch tests and should be comparably evaluated in continuous systems. In this study, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ were added in different concentrations to manure wastewater, and the effects were compared in both batch and continuous systems. The results were used to demonstrate suitable trace element compositions for AD of dairy and swine wastewater, and to compare the outcomes from batch and continuous systems. Fe2+ and Zn2+ were identified as being the most efficient stimulant of dairy and swine wastewater respectively. The addition of 5 mg/L Fe2+ and 0.4 mg/L Zn2+ increased the batch specific methane yield by 62% and 126% for dairy and swine wastewater, respectively. Nevertheless, a lower increment of 2% and 21%, for dairy and swine wastewater was obtained in the 120-day continuously-fed experiments. The 16S rRNA gene sequencing results indicated a relationship between the methanogens population, specific methanogenic activities, propionate, and dissolved hydrogen. Conclusively, the addition of a low dosage of Fe2+ and Zn2+ is a feasible strategy to enhance the methanogenic metabolism of the AD of dairy and swine wastewater respectively.

Air Supplement as a Stimulation Approach for the In Situ Desulfurization and Methanization Enhancement of Anaerobic Digestion of Chicken Manure

“…During the S3 stage, the soluble iron in R2 increased to 75.8 mg/L, which was higher by 1.4-fold than that of R1 (54.7 mg/L).The raised soluble iron content in R2 may be ascribed to the mitigation of sulfide in the liquid phase, which blocks precipitation of FeS and “releases” free iron, improving the bioavailability of iron for the microorganism. It was reported that addition of a minute amount of Fe 2+ or Fe 3+ has a significantly positive effect on the AD performance of swine and dairy manure. , The raised soluble iron content attained in this study has a positive effect on the methane yield, as shown in Figure .…”

“…It was reported that addition of a minute amount of Fe 2+ or Fe 3+ has a significantly positive effect on the AD performance of swine and dairy manure. 37,38 The raised soluble iron content attained in this study has a positive effect on the methane yield, as shown in Figure 5.…”

Environmental and Economic Sustainability of Swine Wastewater Treatments Using Ammonia Stripping and Anaerobic Digestion: A Short Review

“…The reduction of the area required for the application of nitrogen-rich digestate after the biogas production and the possibility to treat the air stripped digestate in the wastewater plant are other advantages of the combined system AS/AD [41]. The main bacteria in the anaerobic process are hydrogenotrophic Methanocorpusculum, acetoclastic Methanosaeta [88], Methanobacteria, and Methanocorpusculum [89]. Clostridia are generally the most abundant bacteria for hydrolysis and fermentation as they can tolerate high concentrations of volatile fatty acids [89,90], while the Bacilli class easily produces acetate and lactate [88].…”

“…The main bacteria in the anaerobic process are hydrogenotrophic Methanocorpusculum, acetoclastic Methanosaeta [88], Methanobacteria, and Methanocorpusculum [89]. Clostridia are generally the most abundant bacteria for hydrolysis and fermentation as they can tolerate high concentrations of volatile fatty acids [89,90], while the Bacilli class easily produces acetate and lactate [88]. Schröder et al [91] used the liquid fraction of the digestate to recover phosphorous and nitrogen by struvite precipitation; then, the effluent was used for the production of ammonium sulphate by air stripping.…”

Analysis of the Energy and Material Use of Manure as a Fertilizer or Substrate for Biogas Production during the Energy Crisis

“…Although the most promising technology, especially in the case of GHG emissions from the solid fraction or farmyard manure (mixture of feces, urine and straw), seems to be anaerobic digestion, it is not the most efficient substrate in itself, as its biogas productivity is low [83,84]. Several scientific reports indicate a low efficiency of methane fermentation in relation to manure.…”