Microwave enhanced biodegradability of food processing wastewater sludge
Food industry wastewater contains a huge amount of organic matters; therefore in sludge, originating from it, the dosed cations in the precipitation stage of wastewater line altogether with living microorganisms and organic molecules form extracellular polymeric substances (EPS). EPS fraction of slu...
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| Dokumentumtípus: | Tanítási erőforrás |
| Kulcsszavak: | szennyvízkezelés |
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| Online Access: | http://eta.bibl.u-szeged.hu/4372 |
| Tartalmi kivonat: | Food industry wastewater contains a huge amount of organic matters; therefore in sludge, originating from it, the dosed cations in the precipitation stage of wastewater line altogether with living microorganisms and organic molecules form extracellular polymeric substances (EPS). EPS fraction of sludge causes hydrophilic characteristic of sludge, and increases the difficulty achieving effective bioconversion during anaerobic digestion (AD) or aerobic biotransformation processes, e.g. composting. Numerous sludge conditioning methods were developed and investigated to improve the accessibility of organic matter for decomposing bacteria. Microwave (MW) irradiation has been successfully applied in many fields of food technology, organic chemistry, biotechnology and also in environmental engineering. MW pre-treatment has verified positive effects on sludge disintegration and releasing of organic matter into the soluble phase, but combining of it with chemical methods, such as alkali, acid and oxidizer agents, synergetic mechanism was experienced with accelerated decomposition under aerobic and anaerobic condition, as well. Many reports deal with examination of the efficiency of MW irradiation of municipal sludge, but very few of them focus on the development of microwave pre-treatment processes for food industry sludge. Therefore, the aim of our present work is to identify the main influential operating parameters of MW pre-treatments in meat processing wastewater sludge conditioning process with optimization of them for enhanced biodegradability. MW pre-treatments were carried out in a special designed microwave cavity resonator, in which magnetron power is variable continuously in the range of 50W to 700W. To investigate the efficiency of MW pre-treatment the process parameters studied were the microwave power level (MWPL), and the irradiated microwave energy (IMWE). Selected control parameters for MW sludge conditioning were the organic matter solubility index (SLI) calculated from the ratio of soluble to total chemical oxygen demand (COD), and the biodegradation index (BDI) determined from the change of the ratio of biochemical oxygen demand (BOD) to COD. To quantify the change in the degree of anaerobic decomposition batch mesophilic biogas production tests were carried out. Our results verify the applicability of microwave pre-treatment procedure for food industry sludge. MW pretreatments increased the biodegradability and biogas production of meat processing wastewater sludge (MPWS). Investigated process parameters, namely IMWE and also MWPL, had significant effect on the SLI and BDI. MW pretreatments increased the organic matters solubility and the biodegradability of sludge, but the worsening effect of the high intensity irradiation over a certain value of IMWE was also experienced. Results from response surface modeling and optimization show that the optimal condition for MW process of MPWS for highest biodegradability with minimum energy demand was determined at 621 kJ of IMWE and at 2.6 Wg-1 of MWPL. |
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| Terjedelem/Fizikai jellemzők: | 8 |