Showing papers on "Hydraulic retention time published in 2001"
TL;DR: The pilot-scale MAP process achieved an orth-P removal ratio of 94% from an average influent ortho-P concentration of 61 mg/l and had cadmium, lead and mercury concentrations well below the legal limits for fertilisers in Queensland, Australia and can be reused as a valuable slow-release fertiliser.
484 citations
TL;DR: Results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye.
246 citations
TL;DR: An anaerobic-aerobic system including simultaneous methanogenesis and denitrification was introduced to treat organic and nitrogen compounds in immature leachate from a landfill site to enhance the nitrification rate in the following aerobic reactor.
211 citations
TL;DR: Characterized by an oxygen consumption rate, sludge specific activities both for organic decomposition and nitrification of ammonia nitrogen varied with SRT, but volumetric oxygen consumption rates of the membrane bioreactor, representing the whole ability of the process for decomposing pollutants, were enhanced as SRT increased.
210 citations
TL;DR: Anaerobic treatability and methane generation potential of cheese whey were determined in batch reactors and nutrient and trace metal supplementation is vital for the anaerobic treatment of Cheese whey.
202 citations
TL;DR: The PVA particles with the highest nitrification rates under all conditions showed promise as an immobilisation medium, and are amenable to further optimisation for the nitrification of high-strength ammonia wastewaters.
169 citations
TL;DR: Investigation of a hollow fibre membrane bioreactor for hydrogenotrophic denitrification of contaminated drinking water and tests with contaminated water from the Cape Cod aquifer resulted in an increase in product water turbidity and dissolved organic carbon (DOC) concentrations.
Abstract: The objective of this research was to investigate the performance of a hollow fibre membrane bioreactor (HFMB) for hydrogenotrophic denitrification of contaminated drinking water. In the HFMB, H2 flows through the lumen of the hydrophobic hollow fibres and diffuses to an attached H2 oxidizing biofilm. Nitrate in the contaminated water serves as an electron acceptor. A hydrogenotrophic denitrifying culture was enriched from a wastewater seed. Batch culture experiments were conducted to compare heterotrophic (methanol as electron donor) and hydrogenotrophic denitrification rates and to investigate the conditions required for the HFMB studies. The batch cultures demonstrated mixotrophy, with denitrification rates of 30 g NO−3-N m−3 d−1 for heterotrophic and 18 g NO−3-N m−3 d−1 for hydrogenotrophic conditions. A laboratory-scale HFMB was constructed that utilized 2,400 polypropylene hollow fibres with an inner diameter of 200 µm, an outer diameter of 250 µm and a 0.05 µm pore size. After a 70-day start-up period, the NO−3 loading rate was gradually increased over a three-month period. The NO−3 utilization rate reached a maximum of 770 g NO−3-N m−3 d−1 at an influent NO−3 concentration of 145 mg NO−3-N l−1 and a hydraulic residence time of 4.1 hours. Influent NO−3 concentrations of up to 200 mg NO−3-N l−1 were almost completely denitrified. Tests with contaminated water from the Cape Cod aquifer resulted in an increase in product water turbidity and dissolved organic carbon (DOC) concentrations.
148 citations
TL;DR: The performance of the AMBR in treating a carbohydrate-rich wastewater was found to be superior in terms of maximum loading rate and SMPR, and the absence of pre-acidification created "bulking" problems in a UASB reactor, operated under conditions similar to that of theAMBR.
142 citations
TL;DR: In this paper, a modified anaerobic baffled bioreactor (MABR) was studied under steady-state conditions for treating palm oil mill wastewater, which corresponded to the methane content of 67.3-71.2% within the range of examined hydraulic retention time (HRT).
134 citations
TL;DR: Experimental values indicated that both bioreactors showed high phenol degradation efficiencies, higher than 90%, even for a phenol loading rate in the influent as high as 4 g phenol/l day.
133 citations
TL;DR: Substrate complexity was observed to be less significant under two-phase, two-stage and UASB reactor configurations and the one stage CSTR--most commonly utilized in the field--was the worst possible reactor configuration.
TL;DR: This study revealed that VFA production was feasible at low temperatures (down to 8 degrees C), particularly in the presence of the industrial waste, and the amount VFA produced was adequate, in most cases, to support subsequent biological nutrient removal (BNR) processes.
TL;DR: An autotrophic biological process was developed for the treatment of nitrate-contaminated drinking water and when detected in the effluent, the concentration of nitrite was low, even under conditions that resulted in the elution of very high concentrations of nitrates.
TL;DR: The UASB/TF system is a very promising alternative for the treatment of domestic sewage in Brazil and other developing countries, since the system can be designed with very short hydraulic retention times, resulting in a very compact and low cost treatment unit.
TL;DR: The partial acidification process to manage swine waste should be operated in the optimum condition for acetic acid production because the optimum operating condition for butyric acid production approached the washout point.
Abstract: Swine wastewater was biologically treated to produce short-chain volatile organic acids (VOAs) in laboratory-scale continuously stirred tank reactors. The maximum production rates of acetic and butyric acids associated with simultaneous changes in pH and hydraulic retention time (HRT) were investigated, in which the degree of acidification of swine wastewater to the short-chain VOAs was <25% of influent chemical oxygen demand (COD) concentration. A constant inoculum system was used to minimize the experimental error due to the use of inconsistent inoculum. The inoculum system was operated with synthetic wastewater at 6000 mg soluble chemical oxygen demand per liter (pH 6.0) and 35°C at 0.5 day hydraulic retention time. Response surface methodology was applied successfully to determine the optimum physiological condition for which the maximum rate of acetic acid production occurred, which was pH 5.90 and 0.88 day hydraulic retention time at 35°C. The partial acidification process to manage swine waste should be operated in the optimum condition for acetic acid production because the optimum operating condition for butyric acid production approached the washout point. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 521–529, 2001.
TL;DR: In this article, the authors describe the thermophilic anaerobic biodegradation of wine distillery wastewater (vinasses) in a laboratory fluidized bed reactor (AFB) with a porous support medium.
TL;DR: An investigation has been made on laboratory scale to assess the feasibility of an anaerobic fixed film fixed bed reactor system to pre-treat herbal-based pharmaceutical wastewater with recourse to energy recovery, including influence of operating conditions.
TL;DR: The feasibility of the compartmentalized anaerobic migrating blanket reactor (AMBR) was studied for the treatment of low-strength soluble wastewater under low-temperature conditions and found that biomass was retained effectively and SCOD removal efficiencies staving greater than 70%.
Abstract: The feasibility of the compartmentalized anaerobic migrating blanket reactor (AMBR) was studied for the treatment of low- strength soluble wastewater under low-temperature conditions. During an operating period of 186 days, a 20-L AMBR was fed nonfat dry milk substrate as a synthetic wastewater at low temperatures (15 and 20 °C). The concentration of the influent was constant at chemical oxygen demand (COD) and 5-day biological oxygen demand (BOD5) concentrations of 600 and 285 mg/L, respectively. The soluble COD (SCOD) removal efficiency was 73% at the end of the operating period (15 °C) at a 4-hour hydraulic retention time (HRT), while the total COD (TCOD) removal efficiency was 59%. At a 4-hour HRT, staged conditions promoted complete removal of propionic acid in the final compartments of the reactor. The specific methanogenic activity of granules increased slowly until the end of the operating time, improving the removal rate. Biomass was retained effectively, as evidenced by the solids retention time (SRT) that was always greater than 50 days even during step decreases of the reactor HRT from 12 hours to 4 hours. A long SRT also promoted system stability during changes in flow, which was observed by SCOD removal efficiencies staying greater than 70%. During a hydraulic stress test, the HRT was reduced from 4 hours to 1 hour for one day (24 HRTs) in which volatile suspended solids (VSS) in the effluent increased from an average background level of 8.7 g/d to 35 g/d and the SRT decreased from 50.5 days to 12.6 days. However, mixed liquor volatile suspended solids concentration decreased only by 1 g/L, and hence a similar COD removal efficiency and biogas production was found one day after the hydraulic stress (as compared to one day before the hydraulic stress). Water Environ. Res., 73, 567 (2001).
TL;DR: Bioaugmentation of POME with mixed culture of nitrifiers (ammonia and nitrite oxidizers) has been identified as an effective tool not only for enhancing nitrification of Pome but also for improving quality of PAME as source of liquid nitrogen fertilizer for use in the agricultural sector, especially in oil palm plantations.
TL;DR: Results of this study demonstrate that required design parameters are different depending on the nutrient being removed in systems simulated by these microcosms.
Abstract: Effects of vegetation, wastewater drawdown, hydraulic retention time (HRT), and media depth on removal of nitrogen, phosphorous, and organic carbon in microcosms were investigated. Synthetic wastewater was added daily to 28 microcosms, and effluent was sampled every 12 days for 132 days. Effluent was analyzed for ammonium (NH4
+-N), nitrate (NO3
−-N), orthophosphate (PO4
3−-P), and total organic carbon (TOC). Average percent removal of NH4
+-N was significantly greater in microcosms containing plants (67%) than in those without plants (29%). Percent removal of PO4
3−-P was also significantly greater in microcosms with plants (42%) than in microcosms without plants (20%), but no significant difference was found for TOC removal between microcosms with plants (67%) and those without plants (74%). Average removal was significantly lower in microcosms with wastewater drawdown than in those without wastewater fluctuation for both NH4
+-N (51% versus 83%) and PO4
3−-P (14% versus 71%). Percent NH4
+-N removal was significantly greater in microcosms with a 6-day retention time (80%) than in those with a 2-day retention (53%), and PO4
3−-P removal was also significantly greater with a 6-day retention time (55%) than a 2-day retention (29%). No differences were seen in TOC removal due to any of the treatments but HRT, where removal was greater microcosms with a 2-day HRT (76%) than in those with a 6-day HRT (60%). Media depth did not have a significant effect on nutrient removal. Results of this study demonstrate that required design parameters are different depending on the nutrient being removed in systems simulated by these microcosms.
TL;DR: In this article, the authors evaluated the performance of a marine recirculating aquarium system with immobilized nitrifiers and found that the ammonia removal efficiency rate was 98% with 23 g ammonia-N/m3/day, while the salt concentration was related to the time to stabilize the system.
TL;DR: Methane production rate during the anaerobic stage was adversely affected by accumulations of formaldehyde in the reactor causing lower formaldehyde removal efficiency, however, denitrification proceeded properly even at a formaldehyde concentration of 700 mg L-1 in the reactors, although nitrous oxide appears in the off-gas.
TL;DR: Water extract of Moringa oleifera seeds (WEMOS) was used to enhance the start-up of a self-inoculated upflow anaerobic sludge blanket (UASB) reactor treating raw domestic wastewater, showing an improvement in the performance of the RM compared to that of the RC.
Abstract: Water extract of Moringa oleifera seeds (WEMOS) was used to enhance the start-up of a self-inoculated upflow anaerobic sludge blanket (UASB) reactor treating raw domestic wastewater. Two reactors labelled control (RC) and WEMOS addition (RM) were started without special inoculum. Both reactors were fed continuously for 22 weeks with domestic wastewater containing an average total chemical oxygen demand (COD) of 320 mg O2/l and suspended solid (SS) of 165 mg/l. The reactors operated during the entire experimental period at 29°C and at a hydraulic retention time (HRT) of 4 h. The RM reactor received 2 ml WEMOS per litre of influent. WEMOS solution was prepared on the basis of 2.5% (w/v) ground M. oleifera seeds in water. The results of 22 weeks' operation showed an improvement in the performance of the RM compared to that of the RC. The dosage of WEMOS in the feed (1) shortened the biological start-up period by 20%, (2) increased acidogenic and methanogenic activity by a factor of 2.4 and 2.2 respectively, (3) increased the specific biogas production by a factor of 1.6, (4) favoured fast growth of the sludge bed, and (5) allowed the aggregation of coccoid bacteria and growth of microbial nuclei, which are precursors of anaerobic granulation.
TL;DR: In this paper, the suitability of the first-order removal model was tested to predict metal retention in a young constructed wetland receiving agricultural and urban runoff, and water samples for total and dissolved metal analyses were collected every third day at both the inlet and the outlet.
TL;DR: One isolate recovered from the biofilm was shown to be capable of degrading 4-CP as a sole carbon and energy source.
Abstract: Using a continuous enrichment technique, a bacterial consortium capable of degrading 4-chlorophenol (4-CP) was obtained from the rhizosphere of Phragmites australis A granular activated carbon (GAC) biofilm reactor was established using this consortium, and the degradation of 4-CP was investigated under continuous flow operation using a feed of 20-50 mg l(-1) with a hydraulic residence time of 17 min over a 6-month period Chloride liberation occurred throughout the operation, and the reactor had 4-CP removal efficiencies of 69-100% Periods of lower performance were attributed to clogging of the column with biomass and the formation of channels Subsequently, the immobilized biofilm was subjected to a starvation period of 5 months, after which its degradative capacity was still maintained The microbial consortium was characterized during the continuous flow experiment and dynamic population changes were observed throughout One isolate recovered from the biofilm was shown to be capable of degrading 4-CP as a sole carbon and energy source
TL;DR: The processing of solid vegetable market waste was attempted in a two-stage digester and the effect of waste-liquid ratio, dilution and sprinkling rate on the digestion of waste were studied.
TL;DR: Coagulation and digestion of tannery wastewater were investigated in this paper, and the results indicated that coagulation considerably reduced the concentration of sulphide and improved the anaerobic treatability.
TL;DR: SCOD removal efficiency of 90 +/- 3% was achieved by both systems at an organic loading rate, indicating that the installation of an acidification reactor had no effect in terms of the maximum granular activity, biomass granulation and the settleability of granules.
TL;DR: A laboratory-scale study was conducted to evaluate the efficiency of a fluidized bed reactor operated under anaerobic condition with bioaugmentation to treat the cephalexin containing pharmaceutical factory effluent to show that bioaumentation could be used to promote biological treatment to applications where conventional operation might be difficult or unfavourable.
TL;DR: The results indicate that this procedure can be used to cultivate seed sludge for hydrogen production from sewage sludge resulting in a large hydrogen production in less than 60 days.
Abstract: The procedure for starting-up continuously stirred tank reactors (CSTR) for acclimating anaerobic hydrogen-producing microorganisms with sewage sludge was investigated. Initially, feeding with glucose and sucrose as well as mixing were carried out in semi-continuous mode; hydraulic retention time (HRT) was in an order of 20, 15, 10, 5, 2.5 and 2 days. When the pH declined to its lowest value (pH 5.18), it was adjusted to 6.7 using sodium hydroxide (I N). At the same time, the semi-continuous operation was changed to a continuous one. Finally, the pH was continuously regulated at approximately 6.7. The results indicate that this procedure can be used to cultivate seed sludge for hydrogen production from sewage sludge resulting in a large hydrogen production in less than 60 days. When the substrate was glucose, a hydrogen yield of 1.63 mol H 2 /mol glucose and a specific hydrogen production rate of 321 mmol H 2 /g VSS day at an HRT of 13.3 h was achieved. When the substrate was sucrose with the same HTR, a hydrogen yield of 4.45 mol H 2 /mol sucrose and a specific hydrogen production rate of 707 mmol H 2 /g VSS day was obtained.