Ferrer I.,University of Barcelona |
Ferrer I.,Technological Center |
Vazquez F.,Autonomous University of Barcelona |
Font X.,Composting Research Group
Bioresource Technology | Year: 2010
The aim of this study was to evaluate the performance of thermophilic sludge digestion at decreasing sludge retention time (SRT) and increasing organic loading rate (OLR), in terms of methane production, effluent stabilisation, hygienisation and dewaterability. Focus was put on determining indicators to help prevent process failure. To this end, a lab-scale reactor was operated for nearly 2 years at 55 °C. Methane production rate was increased (from 0.2 to 0.4-0.6mCH43 mreactor- 3 d-1) by decreasing the SRT from 30 to 15-10 days, while increasing the OLR from 0.5 to 2.5-3.5 kg VSmreactor- 3 d-1. Sludge dewaterability was worsened at SRT below 15 days; while pathogen destruction was always successful. The following concentrations might be used to prevent process failure: VFA C2-C5 (3.7 g COD L-1), acetate (0.6 g L-1), acetate/propionate (0.5), intermediate alkalinity (1.8 g CaCO3 L-1), intermediate/partial alkalinity (0.9), intermediate/total alkalinity (0.5), CH4 in biogas (55%). © 2009 Elsevier Ltd. All rights reserved.
Zulkeflee Z.,University Putra Malaysia |
Zulkeflee Z.,Composting Research Group |
Sanchez A.,Composting Research Group
Water Science and Technology | Year: 2014
An innovative approach using soybean residues for the production of bioflocculants through solid-state fermentation was carried out in 4.5 L near-to-adiabatic bioreactors at pilot-scale level. An added inoculum of the strain Bacillus subtilis UPMB13 was tested in comparison with control reactors without any inoculation after the thermophilic phase of the fermentation. The flocculating performances of the extracted bioflocculants were tested on kaolin suspensions, and crude bioflocculants were obtained from 20 g of fermented substrate through ethanol precipitation. The production of bioflocculants was observed to be higher during the death phase of microbial growth. The bioflocculants were observed to be granular in nature and consisted of hydroxyl, carboxyl and methoxyl groups that aid in their flocculating performance. The results show the vast potential of the idea of using wastes to produce bioactive materials that can replace the current dependence on chemicals, for future prospect in water treatment applications. © IWA Publishing 2014.
Ponsa S.,Composting Research Group |
Gea T.,Composting Research Group |
Sanchez A.,Composting Research Group
Waste Management | Year: 2010
Modern mechanical-biological waste treatment plants for the stabilization of both the source-separated organic fraction of municipal solid wastes (OFMSW) and the mixed stream of municipal solid wastes (MSW) include a mechanical pretreatment step to separate recyclable materials such as plastics, glass or metals, before biological treatment of the resulting organic material. In this work, the role of storage and mechanical pretreatment steps in the stabilization of organic matter has been studied by means of respiration techniques. Results have shown that a progressive stabilization of organic matter occurs during the pretreatment of the source-separated OFMSW, which is approximately 30% measured by the dynamic respiration index. In the case of mixed MSW, the stabilization occurring during the reception and storage of MSW is compensated by the effect of concentration of organic matter that the pretreatment step provokes on this material. Both results are crucial for the operation of the succeeding biological process. Finally, respiration indices have been shown to be suitable for the monitoring of the pretreatment steps in mechanical-biological waste treatment plants, with a strong positive correlation between the dynamic respiration index and the cumulative respiration index across all samples tested. © 2009 Elsevier Ltd. All rights reserved.