In this study, an acclimated manganese-oxidizing bacteria (MnOB) consortium, QBS-1, was enriched in an acid mine area; then, it was used to eliminate Mn(Ⅱ) in different types of wastewater. QBS-1 presented excellent Mn removal performance between pH 4.0 and 8.0, and the best Mn-removal efficiency was up to 99.86% after response surface methodology optimization. Unlike other MnOB consortia, the core bacteria of QBS-1 were Stenotrophomonas and Achromobacter, which might play vital roles in Mn removal. Besides that, adsorption, co-precipitation and electrostatic binding by biological manganese oxides could further promote Mn elimination. Finally, the performance of the Mn biofilter demonstrated that QBS-1 was an excellent inoculant, which indicates good potential for removing Mn contamination steadily and efficiently.

Emissions from Canadian landfills account for 20 % of national greenhouse gas emissions, a portion of which occur as fugitive emissions. Depending on management factors, significant quantities of landfill gas are emitted during the operational phase and over several decades following landfill closure. Successful landfill reclamation developments depend on low-maintenance solutions to manage fugitive emissions. Designing passive methane oxidation biosystems (PMOBs) to complement landfill covers has become a promising complementary strategy. Achieving year-round methane oxidation in cold climates, requires specific conditions for survival of methanotrophic bacteria (responsible for methane oxidation), including optimal temperature, moisture and sufficient supply of O2 and CH4. The objective of this study was to design, construct and monitor a fully instrumented pilot-scale PMOB capable of abating fugitive methane emissions from a closed landfill in the city of Kitchener, Ontario, now a public park. Factors considered in the design include type of PMOB media, methane loading rates, hydraulic behaviour and ambient temperature. Methane oxidation efficiencies between 73 and 100 % were achieved during the monitoring period. The goal was to develop a long-term solution to mitigate fugitive methane emissions at this closed landfill. Successful mitigation will provide a low-maintenance, high impact technology that could be adopted by the municipality for abatement of CH4 emissions at other landfills under its management. The results will also be useful to landfill designers, operators, and regulatory bodies. Overall, the PMOB construction and monitoring results supported evidence that the designed PMOB was capable of abating most of the CH4 loading. The paper describes several steps taken to design, install and operate the PMOB.

In addition to the adsorption capability for organic compounds, granular activated carbon (GAC) can also serve as a good media for the growth of microbial communities in biofilters. Despite its potential, the application of BAC filtration for municipal wastewater treatment has been little addressed in the literature. In this context, this paper aimed to investigate BAC filtration as a post-treatment of anaerobic effluent in pilot scale and its performance in removing organic matter and turbidity. Removal efficiencies during the biofilters run times and along biofilters depth were also evaluated. Three BAC filters were evaluated under different operating conditions of filtration rates (from 13 to 32 m d-1) and empty bed contact time (EBCT) (from 45 to 112 min) during 170 days. The lowest filtration rate (13 m d-1) presented the best performance in terms of dissolved organic carbon (DOC) removal (68.2 ± 4.0%), leading to mean DOC effluent concentration of 6.8 ± 0,9 mg L-1. The BAC reached the stability of biological activity from the 63rd day of operation, however, the adsorption process was still occurring contributing to DOC removal. These DOC removals were higher than those results reported in the literature for BAC filters treating drinking water and municipal wastewater. The DOC removal efficiencies were maintained during the filter run times, showing the robustness of the system even after the interference caused by the backwashing process. BAC filtration was also capable of removing turbidity, with removal efficiencies between 84.5 ± 3.6% and 70.63 ± 6.8% depending on the filtration rate. The results indicated the capability of BAC systems to remove efficiently organic carbon and turbidity from effluents with high organic content, mean of 23.97 (±3.96) mg.L-1, and also valuable support to determine adequate operating parameters for BAC filters application in secondary effluent treatment, such as filtration rate (13 m d-1), EBCT (112 min), and detailed backwashing procedures.

OBJECTIVE: Biofiltration is one of the most accepted technologies in odor control in wastewater facilities. A biofilter system consists of a bed of organic material providing both as the carrier for the active microorganisms and as nutrient supply. This study was aimed to evaluate and model a biofilter performance operated under real conditions of odor emission from a wastewater pump station located in Khorramabad, Iran.
METHODS: The media was a mixture of compost and wood chips with a weight ratio of 5:1. The treatment performance of the biofilter was assessed during a 90-day operation period and the gathered data were utilized to develop and determine the best fit kinetic model based on Michaelis-Menten and Ottengraf models. The best fit model was used in the analysis of scenarios defined based on inlet H2S loading fluctuations. Also, the effectiveness of the main parameters in biofilter performance was evaluated using a dimensionless sensitivity coefficient.
RESULTS: The best fit model was found the Ottengraf zero-order type limited by diffusion based on the values of R-square (0.98) and mean square error (MSE) (0.002). The results demonstrated a high H2S removal efficiency of about 98% in an EBRT (empty bed residence time) of 60 s. despite high fluctuations of inlet concentration under real conditions. The system was able to meet the effluent standard limit of 10 ppm even if the inlet H2S loading increases up to two times the base level. According to the results of the defined sensitivity coefficient, the system performance was more sensitive to the inlet concentration than EBRT with a ratio of 1.4.
CONCLUSIONS: In addition to the acceptable efficiencies of biofilter in odor removal, the results proved the worth of using a kinetic model in forecasting the system performance which is a useful tool in the design and operation of such systems.