Recent Papers in Anaerobic Processes
Content Table
Anaerobic digestion of the organic fraction of municipal solid waste in a two-stage membrane process
Water Science & Technology—WST Vol 60 No 8 pp 1965–1978 © IWA Publishing 2009 doi:10.2166/wst.2009.498
A. P. Trzcinski and D. C. Stuckey
Department of Chemical Engineering, Imperial College of Science and Technology and Medicine, Prince Consort Road, London SW7 2BY, UK E-mail: a.trzcinski@ic.ac.uk; d.stuckey@ic.ac.uk
Abstract
A batch of the Organic Fraction of Municipal Solid Waste (OFMSW) was treated in a two-step process with effluent recirculation comprising a novel hydrolytic reactor (HR) followed by a Submerged Anaerobic Membrane Bioreactor (SAMBR) operating at a stable permeate flux of 5.6 L/m2 hr (LMH). A soluble COD removal higher than 95% was obtained from the SAMBR. The soluble COD as well as the Total Suspended Solids (TSS) did not build up due to efficient hydrolysis inside the SAMBR, and no VFA accumulation occurred due to the complete retention of methanogens by the membrane as well as the formation of syntrophic associations. Because of the microfiltration membrane in the second reactor a stabilized leachate was obtained from the very first days of the treatment and the highly stable process enabled shorter treatment periods compared to traditional leach bed processes. This experiment showed that the recycle of the stabilised leachate does not lead to a build up of SCOD. Size exclusion chromatography analysis confirmed that high molecular weight compounds were completely degraded and did not appear in the SAMBR permeate, and that low molecular weight fulvic-like and medium MW material were present in the permeate of the SAMBR but their concentration remained stable with time.
A simple method to evaluate the short-term biogas yield in anaerobic codigestion of WAS and organic wastes
Water Science & Technology—WST Vol 58 No 8 pp 1615–1622 © IWA Publishing 2008 doi:10.2166/wst.2008.502
D. Scaglione, S. Caffaz, E. Ficara, F. Malpei and C. Lubello
Dipartimento di Ingegneria Civile e Ambientale, Università di Firenze, Via Santa Marta 3, 50139, Firenze, Italy E-mail: davide@dicea.unifi.it
Publiacqua SpA, Via Villamagna 39, 50126, Firenze, Italy E-mail: s.caffaz@publiacqua.it
D.I.I.A.R. – Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy E-mail: elena.ficara@polimi.it
Abstract
The present study was aimed at setting and applying a procedure to measure the anaerobic degradability of different organic substrates by short-term tests (2–7 days) carried out at lab-scale with a low food to biomass (F/M) ratio. All tests were carried out using an acclimated sludge taken from a pilot-plant anaerobic digester (200 L). Trials were performed with a manometric system.
The experimental reliability of the device in measuring the anaerobic degradability was assessed by several preliminary tests carried out using acetate and glucose as reference substrates. The average conversion to methane was 99% for acetate and of 83% for glucose. The results of tests in triplicate showed the high repeatability of the method with an average coefficient of variation lower than 2%.
Then, the lab-scale procedure was applied to study the short-term anaerobic degradability of complex organic substrates: thickened waste activated sludge, two kinds of organic fraction of municipal solid waste (a kitchen waste and a fruit and vegetable waste collected at the wholesale market of Florence), olive mill wastewater and freshly harvested grass. Results indicated that organic fraction of municipal solid waste, olive mill wastewater and grass were characterized by a much higher anaerobic degradability if compared to the thickened activated sludge, well in agreement with literature data.
Energy- and CO2-reduction potentials by anaerobic treatment of wastewater and organic kitchen wastes in consideration of different climatic conditions
Water Science & Technology—WST Vol 58 No 2 pp 379–384 © IWA Publishing 2008 doi:10.2166/wst.2008.363
D. Weichgrebe, I. Urban and K. Friedrich
Institute of Water Quality and Waste Management (ISAH), Leibniz Universität Hanover, Welfengarten 1, D-30167, Hannover, Germany E-mail: weichgrebe@isah.uni-hannover.de; urban@isah.uni-hannover.de; friedrich@isah.uni-hannover.de
Abstract
The classical municipal wastewater treatment in Germany consists of an aerobic carbon and nitrogen elimination and mostly an anaerobic sludge treatment. Organic kitchen wastes from separate waste collection as well as yard wastes are converted mostly in composting plants to soil conditioner. With these conventional types of treatment, the energy potential in waste and wastewater is lost due to aerobic material conversion.
In this article three scenarios for the treatment of municipal wastewater and waste are compared on the subject of energy efficiency and useable potential: Sc1. the classical wastewater treatment and the composting of the organic waste fraction, Sc2. the anaerobic treatment of wastewater combined with deammonification and the digestion of the organic waste fraction, and Sc3. a mutual anaerobic treatment of wastewater and waste as co-digestion with deammonification. The calculation of energy and CO2-balance considers different climatic conditions. In case of using anaerobic treatment, not only the energy balance will be positive, also the CO2-balance is improved by the substitution of fossil fuels with generated biogas
Use of microaerobic conditions for the improvement of anaerobic digestion of solid wastes
Water Science & Technology—WST Vol 58 No 7 pp 1491–1496 © IWA Publishing 2008 doi:10.2166/wst.2008.493
P. Jenicek, F. Keclik, J. Maca and J. Bindzar
Institute of Chemical Technology Prague, Technicka 5, 166 28, Prague 6, Czech Republic E-mail: pavel.jenicek@vscht.cz
Abstract
The treatment of solid wastes containing slowly biodegradable compounds or high level of sulphur compounds was carried out. In both cases the application of microaerobic conditions (that means controlled dosing of small amount of air or oxygen into digester) was an efficient tool to increase the biodegradability of treated material and/or to increase the activity of methanogenic bacteria by removal of their inhibitor.
Enhancement of food waste digestion in the hybrid anaerobic solid-liquid system
Water Science & Technology—WST Vol 57 No 9 pp 1369–1373 © IWA Publishing 2008 doi:10.2166/wst.2008.081
X. Y. Liu, H. B. Ding, S. Sreeramachandran, O. Stabnikova and J. Y. Wang
School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore E-mail: liux0012@ntu.edu.sg; sunand@ntu.edu.sg; costab@ntu.edu.sg; jywang@ntu.edu.sg
Abstract
The hybrid anaerobic solid-liquid (HASL) system is a modified two-phase anaerobic digester for food waste treatment. To enhance the performance of anaerobic digestion in the HASL system, thermal pre-treatment (heating at 150°C for 1 h) and freezing/thawing (freezing for 24 h at-20°C and then thawing for 12 h at 25°C) were proposed for food waste pre-treatment before the anaerobic digestion. Both processes were able to alter the characteristics and structure of food waste favoring substance solubilization, and hence production of methane. However, there was no net energy gain when the energy required by the pre-treatment processes was taken into account.
Anaerobic digestion of catering wastes: effect of micronutrients and retention time
Water Science & Technology—WST Vol 57 No 5 pp 687–692 © IWA Publishing 2008 doi:10.2166/wst.2008.092
M. A. Climenhaga and C. J. Banks
School of Civil Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK E-mail: mac2@soton.ac.uk; cjb@soton.ac.uk
Abstract
Source-separated foodwastes collected from a campus catering facility were processed in bench-scale single-stage anaerobic digesters. The feedstock contained a varied mix of fruits, vegetables, meats and fried foods. A constant organic loading rate (OLR) was maintained with differing hydraulic retention times (HRT). Regular addition of trace elements or prolonged retention time allowed stable digestion at high total volatile fatty acid (TVFA) levels. Reactors on HRT of 25, 50, and 100 days with no micronutrient supplementation exhibited methanogenic failure after approximately 40, 100 and 90 days respectively, while duplicate reactors with micronutrient supplementation maintained stable digestion. An extended HRT of 180 days has so far allowed continued digestion (for reactors with and without micronutrient supplementation) at levels of ammonia nitrogen exceeding 5.7 g l-1 and volatile fatty acid levels exceeding 15 g l-1, usually considered inhibitory or toxic.
Low temperature anaerobic biotreatment of priority pollutants
Water Science & Technology—WST Vol 57 No 4 pp 499–503 © IWA Publishing 2008 doi:10.2166/wst.2008.056
R. M. McKeown, G. Collins, F. A. Chinalia, T. Mahony and V. O'Flaherty
Microbial Ecology Laboratory, Department of Microbiology and Environmental Change Institute, National University of Ireland, University Road, Galway, Ireland r.mckeown2@nuigalway.ie; gavin.collins@nuigalway.ie; chinalia@hotmail.com; therese.mahony@nuigalway.ie; vincent.oflaherty@nuigalway.ie
Abstract
The effect of low operating temperature and pollutant concentration on the performance of five anaerobic hybrid reactors was investigated. Stable and efficient long-term (>400 days) treatment of a cold (6–13°C), volatile fatty acid (VFA)-based, wastewater was achieved at applied organic loading rates (OLRs) of 5 kg chemical oxygen demand (COD) m-3 d-1 with COD removal efficiencies c. 84% at 6°C (sludge loading rate (SLR) 1.04–1.46 kg COD kg [VSS]-1 d-1). VFA-based wastewaters, containing up to 14 g pentachlorophenol (PCP) m-3 d-1 or 155 g toluene m-3 d-1 were successfully treated at applied OLRs of 5–7 kg COD m-3 d-1. Despite transient declines in reactor performance in response to increasing toxicant loading rates, stable operation (COD removal efficiencies > 90%) and satisfactory toxicant removal efficiencies (>88%) were demonstrated by the systems.
Two-stage anaerobic digestion enables heavy metal removal
Water Science & Technology—WST Vol 57 No 4 pp 553–558 © IWA Publishing 2008 doi:10.2166/wst.2008.054
Robert Selling, Torbjörn Håkansson and Lovisa Björnsson
Department of Biotechnology, Lund University, PO Box 124, SE-22100, Lund, Sweden lovisa.bjornsson@biotek.lu.se
Abstract
To fully exploit the environmental benefits of the biogas process, the digestate should be recycled as biofertiliser to agriculture. This practice can however be jeopardized by the presence of unwanted compounds such as heavy metals in the digestate. By using two-stage digestion, where the first stage includes hydrolysis/acidification and liquefaction of the substrate, heavy metals can be transferred to the leachate. From the leachate, metals can then be removed by adsorption. In this study, up to 70% of the Ni, 40% of the Zn and 25% of the Cd present in maize was removed when the leachate from hydrolysis was circulated over a macroporous polyacrylamide column for 6 days. For Cu and Pb, the mobilization in the hydrolytic stage was lower which resulted in a low removal. A more efficient two-stage process with improved substrate hydrolysis would give lower pH and/or longer periods with low pH in the hydrolytic stage. This is likely to increase metal mobilisation, and would open up for an excellent opportunity of heavy metal removal.
Anaerobic co-digestion of winery wastewater
Water Science & Technology Vol 56 No 2 pp 49–54 © IWA Publishing 2007 doi:10.2166/wst.2007.471
L. Rodríguez, J. Villaseñor, F.J. Fernández and I.M. Buendía
University of Castilla-La Mancha, Chemical Engineering Department (ITQUIMA), Avenida Camilo José Cela S/N. 13071 Ciudad Real, Spain (E-mail lourdes.rodriguez@uclm.es; jose.villasenor@uclm.es; fcojesus.fmorales@uclm.es; inmaculadam.buendia@uclm.es)
Abstract
The operational performance of anaerobic batch reactors treating winery wastewater (WW) combined with waste activated sludge (WAS) in different proportions was investigated under mesophilic conditions. In these experiments it was shown that for anaerobic digestion of WW alone, methane production rate was lower than the rates achieved when WW and WAS were treated together. When WW was mixed with WAS at a concentration of 50% WW resulted in the highest methane production rates. A simplified anaerobic model was used to determine the main kinetic parameters; maximum COD reduction rate (qDA) and maximum methane generation rate (kmax). The maximum values of qDA and kmax were 16.50 kgCOD COD-1 d-1 and 14.34 kgCOD kgCOD-1 d-1, respectively.
Anaerobic digestion of blackwater from vacuum toilets and kitchen refuse in a continuous stirred tank reactor (CSTR)
Water Science & Technology Vol 55 No 7 pp 187–194 © IWA Publishing 2007 doi:10.2166/wst.2007.144
C. Wendland, S. Deegener, J. Behrendt, P. Toshev and R. Otterpohl
Institute of Wastewater Management and Water Protection, Hamburg University of Technology, Germany (TUHH) (E-mail: c.wendland@tu-harburg.de)
Abstract
The objective of this research was mesophilic anaerobic digestion of blackwater from vacuum toilets (BW) and kitchen refuse (KR) in a CSTR within an ecological sanitation system. A detailed investigation of the BW characteristics was carried out. Research on anaerobic digestion was performed with CSTR of 10 l volume at HRT of 10, 15 and 20 days. The digestion of BW at 20 days HRT showed stable performance without inhibition effects, in spite of relatively high ammonium concentrations. The removal of total and particulate COD was 61% and 53%, respectively, and the methane yield 10 l CH4/cap/day. The addition of kitchen refuse (KR) improved the performance of the CSTR in terms of COD removal efficiency and methane yield. At 20 days HRT the removal of total and particulate COD increased up to 71% and 67%, respectively, and the methane yield to 27 l CH4/cap/day. The results at 15 days HRT showed similar performance. At HRT of 10 days, the anaerobic treatment was limited but reached steady state conditions at higher VFA concentrations in the effluent, with a decrease of COD removal of 30 to 33% and of methane yields of 19 to 21%.
