Effect of Seasonal Temperature on the Performance and on the Microbial Community of a Novel AWFR for Decentralized Domestic Wastewater Pretreatment

Abstract

Due to environmental burden and human health risks in developing countries, the treatment of decentralized domestic wastewater has been a matter of great concern in recent years. A novel pilot-scale three-stage anaerobic wool-felt filter reactor (AWFR) was designed to treat real decentralized domestic wastewater at seasonal temperature variations of 8 to 35 • C for 364 days. The results showed that the average chemical oxygen demand (COD) removal efficiencies of AWFR in summer and winter were 76 ± 7.2% and 52 ± 5.9% at one day and three days Hydraulic Retention Time (HRT), respectively. COD mass balance analysis demonstrated that even though COD removal was lower in winter, approximately 43.5% of influent COD was still converted to methane. High-throughput MiSeq sequencing analyses indicated that Methanosaeta, Methanobacterium, and Methanolinea were the predominant methanogens, whereas the genus Bacillus probably played important roles in fermentation processes throughout the whole operation period. The performance and microbial community composition study suggested the application potential of the AWFR system for the pretreatment of decentralized domestic wastewater.

Immobilized and granular biomass systems

“…As far as biogas production is concerned, Pentassuglia et al (2020) highlighted a clear correlation between biogas yield and operating temperature of the plant (Figure 4.2). This finding is in agreement with other studies reporting that low temperatures led to a reduction in biogas production, even due to an increase in methane solubility in liquid phase (Bandara et al, 2012;Li & Lu, 2017). According to the biogas production measured, the methane yield ranged 104-267 NmLCH 4 /gCOD removed when the AnSBio operate at the lowest and the highest temperature, 14°C and 35°C, respectively.…”

“…As for example, similar results were obtained by Bodík et al (2002), evaluating the performances of an UAF in the temperature range 8-23°C, which found 84-87% COD removal when operating the plant at 15°C. Lower COD removal was obtained by other authors with different biofilters: Li and Lu (2017) reported only a 52 ± 6% COD removal when operating an anaerobic wool-felt filter reactors (AWFRs) during winter (10°C ± 2) at a 3-d HRT. The COD removal efficiency approached 60% when operating temperature was increased to 21°C (spring).…”

“…The selection of an adequate carrier material was one of the key points in many of the published studies. Several materials have been investigated for their suitability as packing material, including glass, peat, powdered minerals, natural zeolite, expanded clay, fibrous carriers, ceramic, polyurethane foam cubes, and a variety of plastic materials (Li & Lu, 2017;Loupasaki & Diamadopoulos, 2012). The appropriate texture and porosity of the support material allow microbial populations to grow attached onto the surface as biofilm and colonize the interstitial spaces as suspended biomass (Kaetzl et al, 2018).…”

“…Another bioreactor operated as UAF was proposed by Li and Lu (2017). They investigated the performance of a pilot-scale three-stage anaerobic wool-felt filter reactor (AWFR).…”

“…This metabolic route is thermodynamically favoured under psychrophilic conditions, due to an increase of gas solubility (Lettinga et al, 2001). The relevant abundance of hydrogenotrophic species compared to acetoclastic methanogens at cooler temperatures has been widely described (Bandara et al, 2012;Li & Lu, 2017;McKeown et al, 2009). Indeed, a few studies focusing on anaerobic processes at low temperature reported a methane content in the biogas close (Serrano León et al, 2018) or even higher than 80% (Smith et al, 2015).…”