(searched for: doi:10.1080/15435075.2014.909362)
Sustainability, Volume 14; https://doi.org/10.3390/su14052702
Dairy industry wastewater is rich in organic content, presenting a high biodegradability, and therefore biological treatments are widely employed. This study aimed to evaluate biosolids production in three systems: activated sludge (AS), movingbed biofilm reactor (MBBR), and sequencingbatch movingbed biofilm reactor (SBMBBR). Simulated dairy wastewater was used at different organic load rates (OLRs): 1.22, 2.87, and 5.44 gCOD L−1d−1. Besides biosolids production, COD, total carbon (TC), and total nitrogen (TN) removal efficiency was evaluated. Biosolids production was measured in the mixed liquor, carrier-adhered biomass, treated wastewater, and surplus sludge. The operational conditions were kept similar for the three systems, with a carrier filling ratio of 50% for MBBR and SBMBBR. The SBMBBR proved to have better performance in the removal efficiencies of COD, TC, and TN for all OLRs studied. The MBBR presented a similar COD and TC removal efficiency as the SBBR for the two highest OLRs (2.87 and 5.44 gCOD L−1d−1). Concerning biosolids production, the MBBR system produced less biomass and delivered the lowest amount of adhered biomass inside the carriers. The AS treatment generated the highest amount of sludge and offered the worst treatment capability for all OLRs evaluated.
Energies, Volume 14; https://doi.org/10.3390/en14030590
The present study aimed to determine the effect of a 17.6 mT static magnetic field (SMF) on the efficiency of anaerobic digestion (AD) of municipal sewage sludge (MSS). The SMF had a significant impact on methane (CH4) production efficiency, the levels of fermentation rate (ηFMSS) vs. removal rate (ηVS), and the structure of the anaerobic bacteria consortium, but it did not affect cumulative biogas production. The highest CH4 yield (431 ± 22 dm3CH4/kgVS) and the highest methane content in the biogas (66.1% ± 1.9%) were found in the variant in which the SMF exposure time was 144 min/day. This variant also produced the highest ηFMSS and ηVS values, reaching 73.8% ± 2.3% and ηVS 36.9% ± 1.6%, respectively. Longer anaerobic sludge retention time in the SMF area significantly decreased AD efficiency and caused a significant reduction in the number of methanogens in the anaerobic bacteria community. The lowest values were observed for SMF exposure time of 432 min/day, which produced only 54.8 ± 1.9% CH4 in the biogas. A pronounced reduction was recorded in the Archaea (ARC915) and Methanosaeta (MX825) populations in the anaerobic sludge, i.e., to 20% ± 11% and 6% ± 2%, respectively.
Energies, Volume 13; https://doi.org/10.3390/en13246626
Technological solutions allowing the increase of the technological efficiency of anaerobic methods of wastewater treatment are still under investigation. The weaknesses of these solutions can be limited by the use of active fillings. The aim of the present study was to determine the impact of fluidized active filling on the effectiveness of anaerobic treatment of sugar-industry effluent, the production efficiency and the qualitative composition of the biogas produced. High, comparable (p = 0.05) effluent treatment results were observed at tested organic load rates between 4.0 and 6.0 kg COD (Chemical Oxygen Demand)/m3·d. The COD removal rate reached over 74%, biogas yields ranged from 356 ± 25 to 427 ± 14 dm3/kg CODremoved and the average methane contents were approximately 70%. A significant decrease in effluent treatment efficiency and methane fermentation was observed after increasing the organic load rate to 8.0 kg COD/m3·d, which correlated with decreased pH and FOS/TAC (volatile organic acid and buffer capacity ratio) increased to 0.44 ± 0.2. The use of fluidized active filling led to phosphorus removal with an efficiency ranged from 64.4 ± 2.4 to 81.2 ± 8.2% depending on the stage. Low concentration of total suspended solids in the treated effluent was also observed.
Environmental Technology, Volume 38, pp 2373-2380; https://doi.org/10.1080/09593330.2016.1262455
The aim of this study was to determine the effect of a static magnetic field (SMF) on the composition of activated sludge biocenosis. The experiment was carried out in two parallel bench scale Sequencing Batch Reactors (SBRs). Both SBRs were treated with dairy wastewater. The activated sludge in the first SBR was exposed to an SMF via the induction of a 0.6 T magnetic field generated by four magnetic liquid activators. The second reactor (control reactor) was operated at the same operational parameters but the activated sludge was not exposed to the SMF. The mean length of the bacterium Eikelboom Type 0092 was lower in the SMF-exposed reactor than in the control reactor. Different activated sludge morphologies in SBRs were reflected in the values of the sludge volume index and sludge biotic index calculated on the basis of the microfauna composition.
Environmental Technology, Volume 37, pp 1656-1663; https://doi.org/10.1080/09593330.2015.1126362
The aim of the study was to determine the impact of the constant magnetic field (CMF) application on the effectiveness of anaerobic digestion of algal biomass. The highest yield of biogas in the range of 448.9 L/kg volatile solids (VS) to 456.6 L/kg VS was observed in the variants, in which the retention time in the CMF-exposed area ranged from 144 to 216 min/d. Under these conditions, the concentration of methane in the biogas was nearly 65.0%. The increase in the contact time of the fermentation medium with the CMF-exposed area had a significant impact of reducing the effectiveness of anaerobic digestion. The lowest biodegradation was observed when the retention time was 432 min/d. Under such condition, 281.1 L of biogas/kg VS with methane content of 41.8% was obtained. A correlation between the time of exposure to CMF and the values of parameters characterizing the methane production was found.
Published: 8 May 2015
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, Volume 229, pp 662-676; https://doi.org/10.1177/0957650915584717
Low calorific value of biogas is one of the most important barriers of biogas development in industrial scale. Since biogas upgrading is complicated and not economic, various characteristics of pure biogas combustion have been experimented in recent years. In this paper, the characteristics of biogas flame structure and emissions in nonpremixed vortex combustion are studied experimentally and numerically. A lab-scale asymmetric chamber is employed as an industrial vortex combustor model and characteristics of biogas vortex combustion such as temperature distribution inside the chamber, the flame stability and the combustion emissions are investigated with respect to the various mole fraction of CO2 in the biogas content. The flame structure and emissions were recorded by changing the percentage of CO2 mole fraction in the biogas from 0 to 40% by volume. The results indicate that the stability of nonpremixed biogas combustion decreases when the rate of CO2 mole fraction increases in the fuel. The rate of both CO2 and NO x formation of nonpremixed combustion reduce monotonically when the rate of CO2 fraction increases in the biogas ingredients.