EPS and SMP as Stability Indicators During the Biofiltration of Diffuse Methane Emissions

Abstract

Biofiltration of an air stream polluted with diffuse CH 4 concentrations of 0.19 % (v v −1 ) was carried out. These emissions can be encountered at different industrial facilities such as wastewater treatment plants and landfills. The effect of ammonium supplied in the nutrient solution was studied in a range from 0 to 1 g N-NH 4 + L −1 , taking account its effect on CH 4 removal efficiency (RE), CO 2 production, ammonium conversion and the occurrence of exopolymeric substances. Additional batch assays were performed in order to evaluate the most suitable pH and temperature ranges for the biomass used as inoculum. A conventional biofilter was operated along 225 days achieving maximum CH 4 elimination capacities of up to 11.2 g CH 4 m -3 h −1 , corresponding to REs of 62 %, using 0.52 g N L −1 of ammonia as nitrogen source in the nutrient solution and operating at an empty bed residence time of 4.4 min. CO 2 production values confirmed that most of this elimination was biological and not absorption into the liquid phase. The occurrence of instability periods resulted in a clear increase of the soluble microbial products (SMPs) contained in the liquid phase, especially in the protein fraction, which could be used as a monitoring tool to follow the stress conditions of the biofilter. Results indicate interesting links between the performance of the biofilter and the presence of extracellular polysaccharide and protein concentration in the liquid phase, with increasing concentrations detected when the process was not stable.

Gaseous Emissions from Wastewater Facilities

“…The effect of ammonium (0 to 1 g/L as NH4-N) in the nutrient solution at a conventional biofilter treating an Water Environment Research, Volume 88, Number 10-Copyright © 2016 Water Environment Federation air stream with a CH4 content of 0.19% v/v was studied in regards to CH4 removal, CO2 production, ammonium conversion, and the occurrence of exopolymeric substances (Hernández et al, 2015). The results indicated increased concentrations of extracellular polysaccharide and protein when the process was not stable.…”

Bio-conversion of methane into high profit margin compounds: an innovative, environmentally friendly and cost-effective platform for methane abatement

“…Under non-stressing conditions, EPS productions of 0.03-0.43 g g -1 biomass using gamma methanotrophs (Methylobacter, Methylomonas) have been reported (Malashenko et al 2001). Moreover, recent studies observed that acidification, high salinity and low N concentrations positively influence EPS excretion by microorganisms, whereas EPS accumulation can be inhibit if CH4 and O2 diffusion to the cells is limited (Wilshusen et al 2004;Hernández et al 2015). In this context, a recent publication demonstrated that a consortium composed of methanotrophic and non-methanotrophic bacteria (i.e.…”

Ozonation and Depolymerization of Extracellular Polymeric Substances (EPS) Extracted from a Biofilter Treating Gaseous Toluene

“…Neilsen et al [6] comprehensively discussed the composition of EPS extracted from biofilms in different engineered biological systems, such as in biofilters and trickling filters. Hernández et al [10] confirmed the presence of the largest fraction of protein in EPS extracted from a methane treating biofilter and used changes in protein content as a monitoring tool to study the stress conditions. Furthermore, it was identified that protein constitutes a variety of amino acids, such as glutamic acid, aspartic acid, alanine acid and leucine acid, at a high concentration (about 40% of total proteins in EPS) [11].…”