Showing papers on "Hydraulic retention time published in 1985"
Journal Article•
TL;DR: Biological phosphorus removal was first proposed in 1955 by Greenburgh et al. as discussed by the authors, who suggested that activated sludge could take up phosphorus at a concentration beyond that required for normal growth.
Abstract: Biological phosphorus removal was first proposed in 1955 by Greenburgh et al.1 The authors suggested that activated sludge could take up phosphorus at a concentration beyond that required for normal growth. The progress made since that time is summarized in the publications from two conferences in 1982; the International Association on Water Pollution Research (IAWPR) Post Conference on Phosphorus Removal in Biological Treatment Processes, Pretoria, South Africa,2 and a U. S. Environmental Protection Agency (EPA) Workshop on Biological Phosphorus Removal in Municipal Wastewater Treatment, Annapolis, Md.3 The report on the Annapolis workshop discusses the probable economic advantages of in corporating biological rather than chemical phosphorus removal at treatment facilities. A major conclusion of the report was that biological phosphorus removal is a viable alternative to chemical treatment and should be considered in either retrofit or new plant designs. Proprietary biological phosphorus removal systems are cur rently marketed by several manufacturers. The A/O process is patented and marketed by Air Products and Chemicals, Inc. The system has a short hydraulic retention time. A sludge with approximately 6% phosphorus is wasted from the system.4,5 The Bardenpho system, licensed to the EIMCO Process Equip ment Company in the U. S., has a long hydraulic retention time. Sludge production results in a phosphorus-rich sludge containing 4 to 6% phosphorus.6 The PhoStrip system is marketed by Biospherics Incorporated. Phosphorus removal occurs by lime precipitation of phosphorus that is elutriated from a sludge side stream.7 The University of Cape Town (UCT) process is used with wastewaters containing a low ratio of total chemical oxygen demand to Kjeldahl nitrogen (COD/ TKN)8 with an additional recycle stream for eliminating nitrate from the anaerobic zone. Other systems have been brought to the attention of the authors including a periodic system marketed in Denmark9 but the four mentioned above constitute the major configurations either in operation or being discussed at this time.
65 citations
TL;DR: In this paper, a fixed film loop reactor was developed for the stabilization of undiluted sour whey, and the fermentation system was self-supporting with the aid of a pH-titrator.
Abstract: A fixed film loop reactor was developed for the stabilization of undiluted sour whey. Porous clay beads were used to immobilize the population. The fermentation system was self-supporting with the aid of a pH-titrator. Within 2 months; the loading increased automatically to its maximum of 14 kg COD (chemical oxygen demand)/m3 per day. Parallel to this, the bacterial film was formed on the surface of the support material. For a pH of 6.7 the steady state was reached at a hydraulic retention time of 5 days equivalent to a loading of 14 kg COD/m3 per day. An amount of 5.6 m3 biogas was produced per m3 digester content and day and the COD-reduction was 95%. The pH-controlled whey addition led to only minor disturbances when overloading or oxygenation occured and a fast recovery of methanogenesis was observed. The economics of anaerobic whey digestion compared with conventional whey utilization is estimated by a simple cost/benefit calculation.
58 citations
TL;DR: Palm oil mill effluent was treated anaerobically in 210 dm−3 tank digesters in which inoculation with anaerobic seeding coupled with careful addition of lime could shorten the natural stabilisation process to about 30 days as discussed by the authors.
Abstract: Palm oil mill effluent was treated anaerobically in 210 dm−3 tank digesters in which inoculation with anaerobic seeding coupled with careful addition of lime could shorten the natural stabilisation process to about 30 days. The system was subsequently scaled up to 500 tonnes capacity. The characteristics of the anaerobically digested liquors were studied at 10 and 20 days hydraulic retention time (HRT) respectively, and close to 90% treatment efficiency could be achieved at 20 days HRT with complete microbial conversion of plant cell debris. However, the digested liquor still contained 0.325% (by wt) suspended solids. The kinetics of the anaerobic process show close resemblance to those treating other high strength organic wastes. Optimum gas production occurred only over a narrow pH range of 6.8–7.2 units. A methane content of 62–67% on gas production was noted about equivalent to 0.34 to 0.39 dm−3 CH4 g−1 of BOD destroyed.
37 citations
TL;DR: In this paper, a semi-continuous digester was used to degrade palm oil mill effluent (POME) under mesophilic conditions, achieving a space loading of 12·6 kg COD/m 3 day (hydraulic residence time of 5·6 days).
31 citations
TL;DR: In this paper, the authors compared thermophilic anaerobic fluidized bed Reactor (AFBR) and mesophilic AFBRs to achieve inferior COD removal efficiencies.
Abstract: Thermophilic anaerobic fluidised bed reactors (AFBRs) were shown to achieve inferior COD removal efficiencies in comparison to mesophilic AFBRs treating a synthetic meat waste. Organic removal efficiencies of 45.6–83.7% were observed for mesophilic reactors over a range of COD loadings between 0.5 ‐ 32 kg m‐3 d‐1, while removal efficiencies of the thermophilic reactors were between 33.1–62% over the same range. The optimum hydraulic retention time (HRT) was found to lie within the range of 6–13 h at a COD loading of 4.6 kg m‐3 d‐1. There appeared to be little difference between the optimum HRT for thermophilic and mesophilic reactors.
29 citations
TL;DR: In this article, a pilot plant study on biological removal of phosphorus was conducted over fifteen months to obtain optimum operational conditions and evaluate process performance, which was composed of an anaerobic zone followed by an aerobic zone, and had a capacity of treating 100 m3 municipal wastewater per day.
26 citations
TL;DR: In this paper, a thermophilic, semi-continuous digester was used to degrade palm-oil mill effluent in a semi-condensate environment, achieving treatment rates approaching those of sludge blanket reactors.
26 citations
TL;DR: Results indicate that a large reduction of required reactor volume is possible through application of a fixed‐film concept combined with a liquid–solid separation pretreatment of dairy manure.
Abstract: The technical feasibility of adopting the fixed-film reactor concept for biogas production from screened dairy manure was investigated. The methane production capability of laboratory-scale 4-L anaerobic reactors (conventional and fixed-film) receiving screened dairy manure and operated at 35 degrees C was compared. Dairy manure filtrate with 4.4% total solids (TS) and 3.4% volatile solids (VS) (average value) was prepared from 1:1 manure-water slurry. The feed material was added intermittently at loading rates ranging from 2.34 to 25 and 2.25 to 785 g VS/L d, respectively, for the conventional and fixed-film reactors. Maximum methane production rate (L CH(4)/L d) for the conventional reactor was 0.63 L CH(4)/L d achieved at a 6-day hydraulic retention time (HRT). For the fixed-film reactor the maximum production rate was 3.53 L CH(4)/L d when operated at a loading rate of 262 g VS/L d (3 h HRT). The fixed-film reactor was capable of sustaining a loading of 785 g VS/L d (1 h HRT). The fixed-film reactor performed much better than the conventional reactors. These results indicate that a large reduction of required reactor volume is possible through application of a fixed-film concept combined with a liquid-solid separation pretreatment of dairy manure.
25 citations
TL;DR: In this paper, a fixed-film reactor was used for the high rate production of methane from screened dairy manure under mesophilic temperatures, which enabled the reactors to withstand high organic loadings as well as very short hydraulic retention times down to 1 h.
24 citations
TL;DR: In this paper, a continuous two-step anaerobic digestion of sugar beet pulp as carbon and energy source was carried out, achieving a biogas yield of more than 85% of the theoretical value for total carbon conversion.
Abstract: A continuous two step anaerobic digestion of sugar beet pulp as carbon and energy source was carried out. The loading rates in the acidification reactor were varied from 5 g·1−1·d−1 to 15 g·1−1·d−1 while the hydraulic retention time was in the range of 10 hours to 30 hours; the corresponding values for the methane reactor varied from 2 days to nearly 6 days. With this reactor configuration a biogas yield of more than 85% of the theoretical value for total carbon conversion was achieved resulting in a corresponding COD reduction.
22 citations
TL;DR: The results over one year from bench and pilot scale tests conducted with synthetic and settled domestic wastewaters respectively are reported in this paper, where a two stage (anaerobic-aerobic) system was installed in one of the Rome urban wastewater treatment works.
01 Jan 1985-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering
TL;DR: In this paper, a two-phase anaerobic digestion system with a completely mixed acid reactor was studied using a 2 percent synthetic glucose substrate, and the steady-state performance of the acid phase was studied at pH 4.3 and a hydraulic retention time (HRT) of 4.5 hours for 117 days.
Abstract: A two‐phase anaerobic digestion system with a completely mixed acid reactor was studied using a 2 percent synthetic glucose substrate. The steady‐state performance of the acid phase was studied at pH 4.3 and a hydraulic retention time (HRT) of 4.5 hours for 117 days. Separation of phases was noted under these conditions as methane production in acid reactor was initially less than 10 percent of the total gas. The effects of pH and HRT on the acid phase were observed by adjusting pH levels to A.3 and 6.5 and HRT to 2, 4.5 and 8 hours.
01 Jan 1985
TL;DR: For example, animal waste-related problems have received very little attention until the last few decades, in which remarkable changes have taken place with respect to farm sizes and animal waste production as discussed by the authors.
Abstract: Historically, animal wastes have been used either as fertilizers or as a fuel source (after being dried). Animal waste-related problems have received very little attention until the last few decades., in which remarkable changes have taken place with respect to farm sizes and animal waste production.
TL;DR: A qualitative and quantitative study of the pollutants in the hydrolyzer effluent of the Petrochemical Industries Company (PIC) was undertaken as mentioned in this paper, which involved flow measurements coupled with a routine and intensive collection of wastewater samples, a comprehensive analysis for the determination of a set of 6-11 parameters and 10 heavy metals, and statistical analysis of the results.
TL;DR: In this paper, the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth were evaluated in a 160 dm3 capacity, well-mixed continuous digestion unit at ambient temperature.
Abstract: With a view to evaluate the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth, experiments were conducted in a 160 dm3 capacity, well-mixed continuous digestion unit at ambient temperature. The optimal design of biogas plant using water hyacinth was elucidated, to provide a unit giving a maximum methane yield of 0.16 nm3 kg−1 volatile solids added, which was 60% greater than the conventional plant using cowdung. The calculations of optimal design factors were based on reactor size, hydraulic retention time and volatile solids loading rate; considerations were made of capital cost, running costs and operational revenue.
01 Jan 1985
TL;DR: In this paper, the authors proposed a land application is an attractive and in most cases the only economically feasible method for the final treatment and disposal of piggery wastes, which is the case for most cases.
Abstract: Land application is an attractive and in most cases the only economically feasible method for the final treatment and disposal of piggery wastes.