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Journal ArticleDOI

Volatile Fatty Acids Production through Degradation of Biomass by Anaerobic Digestion (Mesophilic and Thermophilic)

01 Jun 2014-Applied Mechanics and Materials (Trans Tech Publications Ltd)-Vol. 567, pp 172-176
TL;DR: In this article, the authors used anaerobic sludge digester for the production of volatile fatty acids by two different temperatures condition which are mesophilic and thermophilic; 35°C and 55°C respectively.
Abstract: Volatile fatty acids (VFAs) are fatty acids with a carbon chain of six carbons or fewer and usually referred to as short-chain fatty acids (SCFA). Degradation of biomass through anaerobic digestion will produce volatile fatty acid (VFAs) through anaerobic digestion process. The volatile fatty acids obtained can be recovered and used to produce methyl or ethyl esters which, could be advantageously used as additive for biodiesel [1]. Anaerobic digestion is a biological process that can degrade waste organic material by concerted action of a wide range of microorganisms in the absence of oxygen. The objective of this study is to degrade the biomass through anaerobic digestion for the production of volatile fatty acids by two different temperatures condition which are mesophilic and thermophilic; 35°C and 55°C respectively. The production of volatile fatty acids was optimized by varying the cycle period of the digestion process with the concentration of Mixed Liquor Suspended Solid (MLSS) maintained at 8000 mg/L for each cycle. The degradation of biomass was carried out using anaerobic sludge digester which 2L of biomass was digested from day 1 until day 24 (cycle period). The tests of MLSS and Mixed Liquor Volatile Suspended Solid (MLVSS) was conducted by Standard Method 2540-D while test for VFAs was conducted through Standard Method 8196. The highest production of volatile fatty acids was obtained in day 5 of cycle period where the concentration is 441 mg/L as acetic acid (HOAC).
References
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Journal ArticleDOI
TL;DR: There are many sludge management options in which production of energy (heat, electricity, or biofuel) is one of the key treatment steps as discussed by the authors and the most important options are anaerobic digestion, co-digestion, incineration in combination with energy recovery, coincineration in coal-fired power plants, and co-incining with organic waste focused on energy recovery.
Abstract: Treatment of municipal wastewater results worldwide in the production of large amounts of sewage sludge. The major part of the dry matter content of this sludge consists of nontoxic organic compounds, in general a combination of primary sludge and secondary (microbiological) sludge. The sludge also contains a substantial amount of inorganic material and a small amount of toxic components. There are many sludge-management options in which production of energy (heat, electricity, or biofuel) is one of the key treatment steps. The most important options are anaerobic digestion, co-digestion, incineration in combination with energy recovery, co-incineration in coal-fired power plants, co-incineration in combination with organic waste focused on energy recovery, use as an energy source in the production of cement or building materials, pyrolysis, gasification, supercritical (wet) oxidation, hydrolysis at high temperature, production of hydrogen, acetone, butanol, or ethanol, and direct generation of electrical energy by means of specific micro-organisms. Incineration and co-incineration with energy recovery and use of sewage sludge in the production of Portland cement are applied on a large scale. In these processes, the toxic organics are destructed and the heavy metals are immobilized in the ash or cement. The energy efficiency of these processes strongly depends upon the dewatering and drying step. It is expected that these applications will strongly increase in the future. Supercritical wet oxidation is a promising innovative technology but is still in the development stage. With the exception of biogas production, the other biological methods to produce energy are still in the initial research phase. Production of biogas from sewage sludge is already applied worldwide on small, medium, and large scales. With this process, a substantial experience exists and it is expected that this application is getting more and more attention. Besides the increasing focus on the recovery and reuse of energy, inorganics, and phosphorous, there is also an increasing focus to solve completely the problem of the toxic organics and inorganic compounds in sludge. In the assessment and selection of options for energy recovery by means of biological methods, this aspect has to be taken into account.

485 citations


"Volatile Fatty Acids Production thr..." refers methods in this paper

  • ...It has also been used for the treatment of waste activated sludge prior to final disposal and has been employed worldwide [3] where 20%-30% of the sludge Total Solid (TS) is mineralized [4]....

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Journal ArticleDOI
TL;DR: Numbers of cultivable methanogens, estimated by the most probable number (MPN) method, were significantly lower on glucose, acetate and butyrate at the increased operational temperature, while the numbers of hydrogenotrophic methanogen remained unchanged.

229 citations

Journal ArticleDOI
TL;DR: In this paper, a review of various lipid extraction techniques and biodiesel production processes from municipal wastewater sludge is presented, where the extracted lipid is converted to biodiesel by esterification and/or transesterification reaction.
Abstract: Extensive research is being conducted all over the world to produce fuels from renewable biomass. Biodiesel, a renewable liquid fuel produced from lipid sources, is one of the most attractive among the options explored for alternative energy sources. However, 70–80% of the overall biodiesel production cost is associated with raw materials cost. Municipal sewage sludge is readily available at no cost. It contains various lipids and hence it is a promising raw material for biodiesel production. Lipids can be initially extracted from the sludge. Subsequently, the extracted lipid is converted to biodiesel by esterification and/or transesterification reaction. Biodiesel is also produced by in situ transesterification of dried sludge. This paper reviews the various lipid extraction techniques and biodiesel production processes from municipal wastewater sludge.

156 citations


"Volatile Fatty Acids Production thr..." refers background in this paper

  • ...There are some advantages of biodiesel compared to conventional diesel such as renewable, less toxic, biodegradable, low emission, excellent lubricity and could provide similar energy density to diesel [2]....

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Journal ArticleDOI
TL;DR: In this paper, the effect of temperature and requirement for mixing on VFA generation from waste activated sludge (WAS) generated in full scale non-EBPR wastewater treatment plant was investigated.

139 citations


"Volatile Fatty Acids Production thr..." refers result in this paper

  • ...Comparing to other researchers result, [9] has shown that the production of VFAs was up to 2154 mg/l after 6 days of digestion under mesophilic condition with the initial TSS of 9730 mg/l....

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Journal ArticleDOI
TL;DR: Investigation suggests that pH 10.0 could significantly improve the VFA production through the break of sludge matrix, increase the effective contact between extracellular organic matters and enzymes, and create a favorable environment for microbes to accumulate VFA.

105 citations


"Volatile Fatty Acids Production thr..." refers background in this paper

  • ...In another experiment, [10] has shown that the VFAs production was 2500 mg/L and 1200 mg/L for mesophilic and thermophilic condition; respectively, with the initial TSS of 10000 mg/L....

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