Download or read book Acid phase Anaerobic Digestion of Primary Sludge written by Indira J. Maharaj and published by . This book was released on 1999 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acid phase Anaerobic Digestion of Primary Sludge the Role of Hydraulic Retension Time HRT Temperature and Starch rich Industrial Wastewater written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Hydraulic Retention Time HRT and Temperature on the Acid phase Anaerobic Digestion of Primary Sludge and Industrial Wastewater written by Amit Kumar Banerjee and published by . This book was released on 1997 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Hydraulic Retention Time HRT and Temperature on the Acid phase Anaerobic Digestion of Primary Sludge and Industrial Wastewater written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pathogen Destruction Efficiency In High Temperature Digestion written by Donald M. D. Gray (Gabb) and published by IWA Publishing. This book was released on 2004-01-01 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research was to evaluate and compare various thermophilic anaerobic digestion processes for meeting U.S. EPA biosolids Class A pathogen standards. The project was split into three phases. Phase 1 screened three bench-scale thermophilic anaerobic process configurations at three different thermophilic temperatures based on their fecal coliform destruction efficiency. All three of the thermophilic process configurations tested were capable of achieving the Class A fecal coliform standard and were included in Phase 2. In Phase 2, bench-scale anaerobic digesters were fed primary sludge seeded with E.coli, helminth ova, poliovirus, and Salmonella to evaluate pathogen destruction. Two process configurations, the thermophilic single-stage and the two-stage mesophilic acid-phase/thermophilic methane-phase system, met Class A requirements at 50oC. In Phase 3, the single-stage thermophilic anaerobic digestion process was compared to the single-stage mesophilic process at full scale (1.5-MG digesters) based on fecal coliform and pathogen destruction, process performance, digested sludge dewaterability, and odor generation. Pathogen destruction and process performance comparisons of the various process configurations are presented for each phase of the study. Based on the fecal coliform data presented here, an empirical model was developed for quantitatively comparing multiple stage and single-stage thermophilic anaerobic digester performance. The model demonstrates that various combinations of thermophilic temperatures, staging, and residence times can achieve the Class A fecal coliform requirement. This study also suggests that anaerobic digesters operating in the lower thermophilic temperature range (approximately 50?C) are not only capable of achieving Class A requirements but may also produce digested sludges with less odor and lower volatile solids than digesters operating at higher thermophilic temperatures.

Download or read book Two phase Anaerobic Digestion for Enhanced Stabilization and Methanation of Sewage Sludge written by and published by . This book was released on 1992 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Thermal Pretreatment on Digestibility of Thickened Waste Activated Sludge and Primary Sludge in Two stage Anaerobic Digestion written by Rubaiya Sarwar and published by . This book was released on 2015 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigated the effect of high pressure thermal (HPTH) pretreatment on the biodegradability of a mixture of primary sludge (PS) and thickened waste activated sludge (TWAS) in single-and two-stage continues anaerobic digestion. The HPTH was applied to the TWAS only at 1500C and 3 bars for 30 minutes. All the systems were operated at mesophilic temperature (350C). The objective of this study was to evaluate the impact of TWAS pretreatment on hydrolysis and fermentation in acid phase digesters and to evaluate potential for increased methane production in the subsequent methanogenic digester. For the two-stage systems, the impact of hydraulic retention time (HRT) on performance was evaluated at two different conditions. The biodegradability of TWAS after pretreatment was evaluated through BMP tests and an increase of 16% biodegradation was observed with pretreated TWAS (PTWAS) as compared to raw TWAS. The HPTH also increased the solubilisation of TWAS by 25-34%. The biodegradable products generated in the pretreated stage were further hydrolyzed and acidified in the acidogenic stage and produced 2 fold higher VFAs in the pretreated digester compared to the control digester. To evaluate the impact of PT on hydrolysis dynamic tests were employed and a two-component hydrolysis model was fit to the data. The readily biodegradable hydrolysis coefficient (Kr) for the control and pretreated digesters were 3.09 d-1 and 2.53 d-1 respectively. Thus, the overall rates of solubilisation were higher for the control than the pretreated digester. However, the advanced pretreatment stage was capable of producing 10% more VFA/TCOD compared to the control. The dynamic tests showed that despite slower hydrolysis rates in the pretreated digesters this PT was capable of producing higher fermentation products in the pretreated digester of the acidogenic phase. The results of this study showed that the HPTH pretreatment resulted in about a 30% increase in the methane production in both single and two-stage processes. Also, same yield value of 0.16 L CH4/ g TCOD added was found for the pretreated digester in two stage system with 10 day HRT and in the control digester of single stage system with 13 day HRT. Thus, integration of pretreatment with two stage digestion yielded similar methane production to that observed with a control that had an extended HRT.

Download or read book Anaerobic Digestion Processes in Industrial Wastewater Treatment written by Sandra M. Stronach and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: There have been many significant microbiological, biochemical and technological advances made in the understanding and implementation of anaerobic digestion processes with respect to industrial and domestic wastewater treatment. Elucida tion of the mechanisms of anaerobic degradation has permitted a greater control over the biological parameters of waste conversion and the technical advances achieved have reduced the time and land area requirements and increased the cost-effectiveness and efficiency of the various processes presently in use. By product recovery in the form of utilisable methane gas has become increasingly feasible, while the development of new and superior anaerobic reactor designs with increased tolerance to toxic and shock loadings of concentrated effiuents has established a potential for treating many extremely recalcitrant industrial wastestreams. The major anaerobic bioreactor systems and their applications and limitations are examined here, together with microbiological and biochemical aspects of anaerobic wastewater treatment processes. London, June 1986 S. M. Stronach T. Rudd J. N. Lester v Table of Contents 1 The Biochemistry of Anaerobic Digestion 1 1. 1 Kinetics of Substrate Utilisation and Bacterial Growth 3 1. 1. 1 COD Fluxes and Mean Carbon Oxidation State 3 1. 1. 2 Bacterial Growth and Biokinetics 4 1. 1. 2. 1 Growth and Single Substrate Kinetics 4 1. 1. 2. 2 Multisubstrate Systems . 8 1. 2 Kinetics and Biochemistry of Hydrolysis 8 1. 3 Kinetics and Biochemistry of Fermentation and J1-0xidation . 11 1.

Download or read book Green Chemistry for Sustainable Biofuel Production written by Veera Gnaneswar Gude and published by CRC Press. This book was released on 2018-05-24 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Renewable fuel research and process development requires interdisciplinary approaches involving chemists and physicists from both scientific and engineering backgrounds. Here is an important volume that emphasizes green chemistry and green engineering principles for sustainable process development from an interdisciplinary point of view. It creates an enriching knowledge base on green chemistry of biofuel production, sustainable process development, and green engineering principles for renewable fuel production. This book includes chapters contributed by both research scientists and research engineers with significant experience in biofuel chemistry and processes. The book offers an abundance of scientific experimental methods and analytical procedures and interpretation of the results that capture the state-of-the-art knowledge in this field. The wide range of topics make this book a valuable resource for academicians, researchers, industrial practitioners and scientists, and engineers in various renewable energy fields. Key features: • Emphasizes green chemistry and green engineering principles for sustainable process development for biofuel production • Discusses a wide array of biofuels from algal biomass to waste-to-energy technologies and wastewater treatment and activated sludge processes • Presents advances and developments in biofuel green chemistry and green engineering, including process intensification (microwaves/ultrasound), ionic liquids, and green catalysis • Looks at environmental assessment and economic impact of biofuel production

Download or read book Characterization of Acid Phase Anaerobic Digestion of Municipal Sludges to Improve Biological Nutrient Removal Processes written by Antonio Albornoz and published by . This book was released on 2017 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced biological phosphorus removal (EBPR) can improve the balance sheet for waste water treatment plants. However, for phosphate accumulating organisms (PAOs) to work efficiently, there needs to be a readily biodegradable carbon source as their substrate for growth. Side stream hydrolysis and acid-phase fermentation of the sludge can generate readily available carbon in the form of volatile fatty acids (VFAs). The VFAs are subsequently consumed by PAOs to support the phosphorus removal process. Phosphorus is then recovered from the waste activated sludge using various dewatering and sorting methods. This study evaluated modeling of side-stream acid-phase digestion of primary sludge to support consistent production of VFAs and thereby stabilize and optimize phosphorus removal processes. In this regard, hydrolysis processes were focused on since they are typically the rate-limiting step in anaerobic digestion. It was found that the literature fails to provide consistent information to aid in the modeling of this process, particularly with regards to the values of the hydrolysis rate constants and the sensitivity of these constants to environmental factors such as temperature, pH, and sludge composition. An experimental set up consisting of three semi-batch reactors provided data that was subsequently employed in the model evaluation. The reactors were fed with either primary sludge (PS), waste activated sludge (WAS), or a mixture of both (mixed liquor (ML)). The ML set up received 62% PS and 38% WAS by volume. The reactors were fed with sludge from the Elmira WWTP and were operated at an SRT of 6 days. Water quality parameters such as pH, NH3, COD, SS, TKN, VFA, PO4 were monitored using standard analytical methods. It was found that adding WAS to PS increased the hydrolysis of PS solids by 19% based on VFA produced by influent Total COD. BioWin model simulations employed this data to calibrate a baseline model that described the observed VFA production. It was found that traditional anaerobic hydrolysis rate expressions could not describe all data sets consistently. In an effort to improve the universality of the hydrolysis expression, two extensions for the model were considered. The product inhibition extension considered reduced hydrolysis at high VFA concentrations. This model performed well but improved with the second extension regarding enzyme concentration. It was found that including the effect of hydrolytic enzymes in the model can improve the ability of the model to predict results and it is suggested that the follow up research expands in this area to consider more specific enzymes.

Download or read book Acidogenesis in Two phase Anaerobic Treatment of Dairy Wastewater written by Burak Demirel and published by . This book was released on 2003 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: The acid phase of the two phase anaerobic treatment of dairy wastewater was investigated in this study. The purpose was to observe the effects of variations in hydraulic retention time (HRT) on volatile fatty acid (VFA) production and distribution in a laboratory-scale, continuous-flow, completely mixed, mesophilic anaerobic reactor, coupled with a continuous recycling system. The reactor was operated up to an organic loading rate (OLR) of about 9.3 kg COD/m3.day, and at a HRT range from 24 to 12 hours, without pH control, at temperature in a range of 35±1C. At 24 hours of HRT, net VFA production and thus, acidification, was none. The anaerobic reactor performed like that of a conventional single-phase reactor, in terms of COD removal and biogas production. Later, the degree of acidification were 6, 6, 7, 23 and 56 per cent, at HRTs of 22, 20, 18, 16 and 12 hours, respectively. The rates of acid production were also determined to be 0, 0.14, 0.19, 0.23, 0.82 and 3.07 g/l/d, at HRTs of 24, 22, 20, 18, 16 and 12 hours, respectively. The degree of acidification and the rate of acid production increased, as HRT was decreased from 24 to 12 hours. The highest degree of acidification and the highest rate of acid production were both achieved at 12 hours of HRT. Propionic, acetic, butyric, valeric and isobutyric acids were produced significantly during acidogenesis of dairy wastewater. Variations in HRT affected VFA production and distribution substantially. In order to provide acidification at 24 hours of HRT, pH was monitored in the settling tank, instead of the reactor. An average settling tank pH of about 5.2 provided an operating pH of 6.8 in the anaerobic reactor, and consequently, 20 per cent acidification was attained at 24 hours of HRT. In this phase of the study, propionic, valeric, acetic and butyric acids were the major VFAs produced. Caproic acid was also produced at minor amounts. The system was also evaluated from microbiological points of view during the study. The effects of variations in HRT on the bacterial populations present in the anaerobic reactor were monitored, in terms of changes in numbers of total microbial community, autofluorescent methanogens, and morphology of the autofluorescent methanogens. Before inoculation, seed sludge had a specific methanogenic activity (SMA) value of 403 ml CH4/g VSS.d. Medium rods and Methanococcus-like species were determined as the dominant methanogens. At the end of start-up, the specific methanogenic activity (SMA) value was 226 ml CH4/g VSS.d, and Methanococcus-like species and short rods were the dominant methanogens. The number of total bacterial community firstly decreased between 24 and 20 hours, then increased between 18 and 12 hours. The number of autofluorescent methanogens and the ratio between the number of autofluorescent methanogens and the number of total bacterial community varied much with respect to variations in HRT between 24 and 12 hours. The ratio of autofluorescent methanogens to total bacterial community ranged from 5 to 16 per cent. The lowest ratio was determined at a HRT of 12 hours. Variations in HRT also affected the dominant methanogenic species. Methanococcus-like species remained the most dominant methanogen between 24 and 18 hours. Medium rods-short rods, and long rods-medium rods were the dominant methanogens at 16 and 12 hours, respectively. A high number of methanogens were observed in the system at 24 hours of HRT with pH control in the settling tank. The ratio of autofluorescent methanogens to total bacterial community was 15 per cent, and Methanococcus-like and medium rods were the dominant methanogens. Monitoring of pH intermittently in the settling tank and consequent decrease in reactor pH did not affect the ratio of autofluorescent methanogens to total bacterial community significantly, but decreased the methanogenic activity to an extent, and provided an increase in the degree of acidification.

Download or read book Anaerobic Digestion of Wastewater Sludge from Primary Sedimentation and Primary Effluent Filtration written by Stanley R. Dean and published by . This book was released on 1984 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anaerobic Digestion of Waste Activated Sludge written by Roy L. Belser and published by . This book was released on 1983 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anaerobic Digestion Process Stability and the Extension of the ADM1 for Municipal Sludge Co Digested with Bakery Waste written by Morris Elya Demitry and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Uncertainty about anaerobic digestion process stability is the main issue preventing more widespread use of the process as a source of energy recovery in wastewater treatment facilities. The overall objective of this research was to study the feasibility of enhancing biogas production inside wastewater facilities using co-digestion of municipal sludge with bakery waste. Another objective was to improve the stability index and a mathematical model that can be useful tools to predict the process stability of municipal sludge digestion alone, and when it is mixed with bakery waste, as a substrate for microorganisms. Experiments were conducted in three phases. In phase 1, a full-scale anaerobic digester at Central Weber Sewer Improvement District, Ogden, UT, receiving a mixture of primary and secondary sludge, was monitored for one hundred days. Chemical oxygen demand (COD), and volatile solids (VS) mass balances were conducted to evaluate the stability of the digester and its capability of producing methane gas. The COD mass balance accounted for nearly 90% of the methane gas produced while the VS mass balance showed that 91% of the organic matter removed resulted in biogas formation. Other parameters monitored included: pH, alkalinity, VFA, and propionic acid. The values of these parameters showed that the digester was running under stable steady state conditions. At mesophilic temperature, the stability index was determined and equal to 0.40 L (CH4)/ g(Î4VS) In phase 2, the feasibility of adding BW to MS was tested in batch reactors scale. The biogas production was enhanced and the digester was stable until the range of 37- 40% of BW to 63-60% of MS. The ADM1 coefficients were modified to accurately predict the digester performance. The modified model outputs (pH, VFA, and methane) were within acceptable ranges when compared with the observed data from the batch reactors. In phase 3, the feasibility of MS and BW were tested using an Induced Bed Reactor (IBR) with a 50:50% ratio of MS:BW (COD basis). The process was stable during different hydraulic retention times and the ADM1 was modified to predict the stability of the process in the IBR.

Download or read book Effect of Acid and Base Pretreatment on the Anaerobic Digestion of Excess Municipal Sludge written by and published by . This book was released on 2005 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: The treatment and disposal of sewage sludge is a growing problem worldwide due to the continuing increase in sludge production from biological wastewater treatment plants and recent stringent regulations regarding sludge treatment and disposal. To date, the primary disposal methods for the excess sludge produced are landfilling, incineration and application in agricultural or forestland [1]. The high water content of the sludge makes incineration expensive and faces restrictions on disposal in modern landfills due to the tendency to reduce the amount of organic matter applied. Agricultural use seems to be the best options but several constraints exist due to health related problems such as odors, heavy metals content or pathogens and hazardous compounds that may be present in the sludge preventing their use in farming [2]. In this context, anaerobic sludge digestion represents a good sludge treatment alternative, decreasing the amount of solids present in the sludge with consequent reductions in disposal cost. Furthermore, we have to consider the advantage represented by energy recovery in the form of methane production that can be utilized as an energy source at the facility [3]. The present research project evaluates the combined use of hydrochloric acid (HCl) and sodium hydroxide (NaOH) for sludge chemical pretreatment to improve the performance of anaerobic digestion by extending the effectiveness of solids hydrolysis which is considered the rate-limiting step in the process [4]. The effect of temperature and the length of pre-treatment were initially evaluated to optimize the pretreatment process prior to use of any anaerobic treatment. Once the results of this experiment are analyzed, the performance of anaerobic digestion with chemical pretreatment using different combinations of primary and waste activated sludge pretreatment with either acid or base was studied. Two different SRTs for anaerobic digestion, 10 and 20 days, were investigated using duplicate reactors for each condition. Two reactors (number 1 and 6), used as control, were fed with a mixture of untreated primary and waste activated sludge in a mass ratio 1:1 with a combined VSS concentration around 30 g/l. Two reactors (number 2 and 4) were fed with a mixture of primary sludge pretreated with HCl and activated sludge pretreated with NaOH. The last two reactors (number 3 and 5) were fed with a mixture of primary sludge treated with NaOH and activated sludge treated with HCl. The same primary and waste activated sludge mass ratio as the one used to feed the control reactors were maintained in the four reactors fed with the chemically pretreated sludge. Monitored parameters were: TSS, VSS, total and soluble COD, Total Kjheldahl Nitrogen (TKN), Ammonia, Volatile Fatty Acids (VFA), pH, Phosphates, metals concentration, fecal coliforms concentration and gas production and composition. As expected, the results showed that 20 days SRT provided higher VSS and COD removal than 10 days SRT for all the three configurations evaluated. For both SRTs, the mixture of primary sludge treated with NaOH and activated sludge treated with HCl resulted in higher VSS and COD removal. VSS removal averaged from 37.2% in reactor 1 and 38.6% in reactor 6 for the 10 days SRT. Increasing the SRT to 20 days led to 46.6% and 44% VSS removal for reactor 1 and 6, respectively. Reactors 2 and 4 led to an overall average VSS removal of 44% for the 10 days SRT experiment which increased to around 50% in both reactors during the 20 days SRT experiment. For both SRTs, reactors 3 and 5 provided the highest average solids reduction with values around 46% for 10 days treatment and close to 53% for 20 days SRT (Chapter 7.2.1). It has to be considered that, in terms of maximum solids destruction, for the 10 days SRT experiment, a highest solids removal value of 47.8% was achieved in reactor 3 while 56.7% removal was obtained in reactor 5 when the SRT increased to 20 days. A similar trend was obtained when the COD removal has been considered. The two control reactors, 1 and 6, averaged from the 37.2% and 38.1% removal for the 10 days SRT experiment to values around 45% when the SRT was increased to 20 days. An overall average COD removal of 44.5 and 43.2% was achieved in reactors 2 and 4, respectively, for the 10 days SRT experiment and increased to around 47% in both reactors when the SRT was increased to 20 days. For both SRTs, reactors 3 and 5 provided the highest average COD removal with values around 45% for 10 days treatment experiment and close to 51% for 20 days SRT. For both retention times, all reactors exhibited good reproducibility in the replicates. Volatile fatty acids (VFAs) concentration was very low for both 10 and 20 days SRT in all reactors and weekly gas analysis exhibited a methane content of approximately 65%, meaning good overall performance of anaerobic digestion. The research proposed showed that anaerobic sludge digestion can be successfully used as sludge treatment alternative to reduce the amount of solids present in the sludge, with consequent reductions in disposal costs. Furthermore, compared with other sludge pretreatment options, the combined use of strong acid and strong base as chemical sludge pretreatment resulted in a good balance between solids reduction, process stability and cost reduction.

Download or read book Anaerobic Digestion of Solid Waste and Sewage Sludge to Methane written by Steven J. Hitte and published by . This book was released on 1975 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anaerobic Digestion of Organic Solid Waste for Energy Production written by Satoto Endar Nayono and published by KIT Scientific Publishing. This book was released on 2010 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anaerobic digestion of the organic fraction of municipal solid waste as such or together with food waste, press water or patatoes sludge was investigated to equilibrate methane production within a day or over the weekend, when no OFMSW was available. A stable co-digestion process could be achieved with COD degradation between 60 and 80 %. The max. organic loading rates were 28 kg COD/L, d. For stable methane production the OLR during Co-digestion should not excede 22,5 kg/L,