Total CODCr Research Articles

Experimental Study on the Plasticizer Wastewater Treatment by UASB-A/O Process

Plasticizer wastewater of high concentration was experimentally studied by the process of pretreatment of acidification demulsion and Fe-C micro-electrolysis and combined process of UASB and A/O aiming at the CODCr removal in this work. The result showed that the CODCr removal rate of pretreatment process arrived at 56.2% after Fe-C micro-electrolysis reaction of 160 min on the optimal condition of pH 3.5 of acidification demulsion and 1:1.2 of the Fe/C ratio, and meanwhile improved the biodegradability of wastewater. On the other hand, UASB-A/O process could afford 80~85% of the CODCr removal rate under the optimized condition of temperature 30~35 °C, HRT 48h, pH 6.5 for UASB and HRT of aerobic zone 10~12 h, DO of about 3mg/L for A/O basin. The whole system could run at the total CODCr removal rate of 94.53~96.36%, and the system effluent CODCr was 500 mg/L or less.

混凝沉淀–厌氧水解酸化–好氧工艺处理印染废水的中试研究

针对具有有机物含量高、成分复杂、碱度大、可生化性差以及色度高等特点的印染废水，本文采用混凝沉淀–水解酸化–好氧工艺进行了中试规模的处理。运行结果表明，中试系统稳定运行120 d，在进水CODcr 1365 mg/L的情况下，厌氧水解池出水CODcr平均值为600 mg/L，平均去除率24%，B/C由0.2提升至0.33~0.63，厌氧水解池提高了废水的可生化性。好氧池出水CODcr平均值为192 mg/L，系统CODcr总去除率平均值为84%，效果显著。TN、TP的出水均值为31.95 mg/L、1.1 mg/L，平均去除率分别为76%、81%。该工艺具有耐冲击负荷，易操作，简单成熟等优点。 Based on high organic content, complex composition, high alkalinity, poor biodegradability, higher chromi-nance of printing and dyeing wastewater, this paper adopted coagulation precipitation-hydrolysis acidification-aerobic process for pilot scale processing. The result of the experiment, which was operated stably for 120 days, showed that the final effluent concentration of anaerobic tank was 600 mg/L with removal efficiency 24% in the flooding water of CODcr 1365 mg/L.B/C was promoted from 0.2 to 0.33 - 0.63, which meant higher biodegradability. The final CODcr effluent concentration of aerobic pond was 192 mg/L. The total CODcr removal efficiency was 84% that had a signifi-cant effect. The final effluent concentration of TN, TP was 31.95 mg/L, 1.1 mg/L, the average removal rate was 76% and 81% respectively. This technology has advantages of impact resistance, easy operation, simple mature etc.

Quality Monitoring and Property Analysis of Urban Initial Rainwater

Pollutants of urban rainwater runoff on water environment as well as the influencing factors are reviewed. By comparing with combined sewer overflows (CSOs), the paper thinks that urban rainwater runoff pollution control is necessary. Four months road runoff and Combined Sewer Overflows quality monitoring was carried in Luoyang, where indices included suspended solids(SS)，chemical oxygen demand(CODcr), dissolved chemical oxygen demand, Ammonia nitrogen(NH3-N) and total phosphorus(TP).The results showed that the concentrations of pollutants of Combined Sewer Overflows(CSOs)were higher than that of street runoff. Concentrations of pollutants in initial flush were very high, but they descended gradually and approached to the stabilization after a period of flushing. The main pollutants were SS, CODcr and NH3-N. By analyzing the correlation between SS and CODcr, and contrasting the content between total CODcr and dissolved CODcr, it inferred that SS was the main contribution to CODcr. The initial split-flow is suggested to handle the heavily polluted runoff.

Evaluation of Treatment Characteristics and Sludge Properties in a UASB Reactor Treating Municipal Sewage at Ambient Temperature

The evaluation of treatment characteristics and sludge properties of an upflow anaerobic sludge blanket (UASB) process was investigated using a pilot-scale 1.15 m 3 reactor. The UASB, inoculated with digester sludge, was operated at a hydraulic retention time of 8 h at sewage temperatures ranging from 10.6 to 27.7 °C for more than 1100 days. The stable removal efficiencies for total COD Cr and SS were 63 ± 13% and 66 ± 20%, respectively. The average concentration of the retained sludge increased to more than 24.5 gSS/L of the column volume after two years of operation. In summer, the water temperature increased above 20 °C, and biodegradation of solid organic matter was enhanced. The solid retention time was evaluated to be as long as 293 ± 114 days; this is sufficient for mineralisation of solid organic matter, as indicted by a low sludge conversion of 0.029 gVSS/gCOD removed and a growth yield of 0.132 gVSS/gCOD, determined by seasonal sludge profiling. The bacterial communities, based on bacterial 16S rRNA genes in the retained sludge, were significantly diverse. Bacteroidetes and Firmicutes were the dominant phyla of the decomposers of solid organic matter in the library. A Ruminococcus-related clone detected in the Firmicutes phylum acted as a cellulose decomposer. Key word: Anaerobic, UASB, Municipal sewage, Ambient temperature,Sludge

Performance of a pilot-scale sewage treatment: An up-flow anaerobic sludge blanket (UASB) and a down-flow hanging sponge (DHS) reactors combined system by sulfur-redox reaction process under low-temperature conditions

Performance of a wastewater treatment system utilizing a sulfur-redox reaction of microbes was investigated using a pilot-scale reactor that was fed with actual sewage. The system consisted of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with a recirculation line. Consequently, the total CODCr (465±147 mg L(-1); total BOD of 207±68 mg L(-1)) at the influent was reduced (70±14 mg L(-1); total BOD of 9±2 mg L(-1)) at the DHS effluent under the conditions of an overall hydraulic retention time of 12 h, a recirculation ratio of 2, and a low-sewage temperature of 7.0±2.8 °C. A microbial analysis revealed that sulfate-reducing bacteria contributed to the degradation of organic matter in the UASB reactor even in low temperatures. The utilized sulfur-redox reaction is applicable for low-strength wastewater treatment under low-temperature conditions.

Water source protection and industrial development in the Shandong Peninsula, China from 1995 to 2004: A case study

Xiashan Reservoir is the largest reservoir in the Shandong peninsula and the major water supply source for urban, industry and agriculture in Weifang, Shandong Province. In the upstream region of Xiashan Reservoir, its industry development ranged in the top three among 12 districts and counties of Weifang from 1995 to 2004. This study investigated changes of water quality in Xiashan Reservoir and its upstream rivers, and analyzed the key industrial developments and industry structure in the upstream region of Xiashan Reservoir between 1995 and 2004, in order to provide potential implications for planning and conducting Xiashan Reservoir protection and the industry development in the upstream region in the future. Five key industries in the upstream region were investigated between 1995 and 2004, including industrial production, water usage, wastewater treatment, and the discharged pollutants. Results showed that the water quality of Xiashan Reservoir gradually improved between 1995 and 2004 and met the requirements of Class III in 2004. Industrial development in the upstream region has increased nearly 7 times, from US$ 163.67 million in 1995 to US$ 1283.69 million in 2004, and shifted in the past decade from food brewery processing industry as the major industry in 1995 to car manufacture and accessory processing as the major industry in 2004. The amounts of water used by the five key industries in 2004 were lower than that in 1995 because of improvements in water utilization and a shift in industry structure. Correspondingly, the total industrial wastewater discharged changed little from 1995 to 2004, but the total COD Cr discharged was greatly reduced.

Biological phosphate removal using a degradable carbon source produced by hydrothermal treatment of excess sludge

Abstract - The possibility of reusing excess sludge treated by hydrothermal reaction for the purpose of improving the efficiency of the enhanced biological phosphate removal (EBPR) process was investigated. Excess sludge from a fish-processing industry located in Japan was treated in high-temperature and high-pressure water, at a reaction temperature ranging from 200 to 400 o C, a pressure of 1.8 to 30MPa and a constant reaction time of 7 min. For the conditions tested, the results showed that when the reaction temperature was increased the content of readily biodegradable substrate in the total COD Cr increased. In addition, the amount of some volatile fatty acids (VFAs) produced by the hydrothermal reaction increased as reaction temperature increased. From the phosphate release tests under anaerobic conditions, it was possible to demonstrate that not only the VFAs, but also the readily and slowly biodegradable substrates are used as potential carbon source by the phosphate-accumulating organisms (PAOs).

二相循環プロセスによるジャガイモ加工廃棄物の無希釈水素・メタン発酵の特性

A new type of two-phase process for producing hydrogen and methane from food waste was investigated using potato processing waste in this study. In this process a mixing tank, a thermophilic acidogenic reactor (55°C) and a mesophilic methanogenic reactor (36°C) were used in series. The methane-fermentation-mixed liquor was returned to the mixing tank for the dilution of influent food waste. A continuous experiment was conducted by changing the whole process hydraulic retention time (HRT) stepwise from 56 days to 30 days, then 20 days and 15 days. The process was successfully performed for over 290 days until the HRT was reduced to 15 days. A stable and high hydrogen production yield of 1.67 mol H2·mol-1 degraded hexose with a VFA concentration of 10000 to 25000 mgHAc·l-1 was obtained in the thermophilic acidogenic reactor, while a high efficiency of methane fermentation was achieved in the mesophilic methanogenic reactor. As a result, the high VS removal (92%) and total CODcr removal (85-90%) were achieved by the new process at HRTs of 20 to 56 days. The suggested new process was not only possible for the dilution-free treatment of potato processing waste, but also useful for continuous hydrogen fermentation at a high rate.

High-rate thermophilic methane fermentation on short-chain fatty acids in a down-flow anaerobic packed-bed reactor

In order to maximize the efficiency of methane fermentation on short-chain fatty acids, growth media containing acetic acid and butyric acid as major carbon sources were supplied to a thermophilic down-flow anaerobic packed-bed reactor. The organic loading rate (OLR) to the reactor ranged from 0.2 to 169 kg-dichromate chemical oxygen demand(CODcr)/m(3)-reactor/day, corresponding to a hydraulic retention time (HRT) of between 1.4 h and 20 days. Stable methane production was maintained at HRTs as short as 2 h (OLR=120 kg-CODcr/m(3)/day), with the short-chain fatty acids in the feed almost completely removed during the process. The apparent substrate removal efficiency, determined from the total CODcr values in the influent and effluent, was 75% at short HRTs. However, the actual substrate removal efficiency must have been greater than 75%, since a fraction of substrate was also utilized in microbial cell synthesis, and these cells were part of the measured total CODcr.

生ごみの高温・高濃度メタン発酵に及ぼす滞留時間と負荷の影響

Effects of the hydraulic retention time (HRT) and loading rate on thermophilic methane fermentation of the organic fraction of municipal solid waste (OFMSW) were investigated by using a semi-continuous flow completely-mixed reactor. The experiment was conducted at a temperature of 55 °C and a constant influent TS level of 10% by changing the HRT from 5 days to 30days. The results indicate that the HRT of thermophilic digester could be shortened to 5 days without significant decrease in both the organic matter degradation and methane production, and that the digester was successfully operated at the high loading rate up to 31 kg-CODCr·m-3·d-1. The removal efficiencies of TS, VS and total CODCr were, respectively, in the ranges of 73-78%, 76-78%, and 72-75%, and 1 kg of influent TS produced about 0.75 m3 of digestion gas with the methane content of 57-59%. The Stoichiometric formula of the methane fermentation of OFMSW was identified as: C17H29O10N + 6.5H2O → 9.25CH4 + 6.75CO2 + NH4+ + HCO3-, which is in accordance with the experimental results of this study. The first-order reaction was found suitable for describing the degradation of the OFMSW, and kinetic constants for TS, VS and total CODCr were summarized in a table. It is suggested that the applicable HRT for the high-solids digestion of OFMSW could be shortened to at least of 7.5 days, corresponding to the CODCr loading rate of 20 kg-CODCr·m-3·d-1, by adding mineral nutrient to the feed. In addition, the relationships between HRT and various operation parameters were determined quantitatively based on the experimental results.

Ecological analysis of the bacterial system in a full-scale egg-shaped digester treating sewage sludge

A full-scale investigation was conducted to evaluate the treatment performance and the bacterial system in an egg-shaped digester treating sewage sludge. The experiment was continued over one year to measure the methanogenic activities using various substrates and the population levels of various trophic groups of methanogenic bacteria, as well as the degradation of each component of organic matters. A total of 10 full-scale egg-shaped sludge digesters fed with concentrated sludge were investigated in this study. At a retention time of 30 days and mesophilic condition of 36 °C, the average reduction efficiencies of carbohydrates, proteins and lipids, which are the three main components in raw sludge, were 74.2%, 55.2% and 42.2%, respectively. As a result, the removal efficiencies of volatile solids (VS) and total CODcr reached 54.2% and 60%, respectively, and 1 m3 influent concentrated sludge produced 23.3 m3 digestion gas in which methane content was about 60%. The comparison between the specific methanogenic activity and the actual specific methane production rate in the digester suggestes that the retention time of the digester could be reduced from 30 days to 15 days without affecting their performance. In addition, both the hydrogen and acetate-consuming methanogenic bacteria were enumerated on the order of 107 MPN/ml.

Ecological analysis of the bacterial system in a full-scale egg-shaped digester treating sewage sludge

A full-scale investigation was conducted to evaluate the treatment performance and the bacterial system in an egg-shaped digester treating sewage sludge. The experiment was continued over one year to measure the methanogenic activities using various substrates and the population levels of various trophic groups of methanogenic bacteria, as well as the degradation of each component of organic matters. A total of 10 full-scale egg-shaped sludge digesters fed with concentrated sludge were investigated in this study. At a retention time of 30 days and mesophilic condition of 36 °C, the average reduction efficiencies of carbohydrates, proteins and lipids, which are the three main components in raw sludge, were 74.2%, 55.2% and 42.2%, respectively. As a result, the removal efficiencies of volatile solids (YS) and total CODcr reached 54.2% and 60%, respectively, and 1 m3 influent concentrated sludge produced 23.3 m3 digestion gas in which methane content was about 60%. The comparison between the specific methanogenic activity and the actual specific methane production rate in the digester suggestes that the retention time of the digester could be reduced from 30 days to 15 days without affecting their performance. In addition, both the hydrogen and acetate-consuming methanogenic bacteria were enumerated on the order of 107 MPN/ml.