Effect of influent COD/N ratio on biological nitrogen removal (BNR) from high-strength ammonium industrial wastewater

The effect of influent COD/N ratio on biological nitrogen removal (BNR) from high-strength ammonium industrial wastewater was investigated. Experiments were conducted in a modified Ludzack–Ettinger pilot-plant configuration for 365 days. Total nitrification of an influent concentration of 1200 mg NH₄⁺–N l⁻¹ was obtained in this period. Influent COD/N ratios between 0.71 and 3.4 g COD g N⁻¹ were tested by varying the nitrogen loading rate (NLR) supplied to the pilot plant. An exponential decrease of nitrification rate was observed when the influent COD/N ratio increased.

The experimental COD/N ratio for denitrification was 7.1±0.8 g COD g N⁻¹ while the stoichiometric ratio was 4.2 g COD g N⁻¹. This difference is attributable to the oxidation of organic matter in the anoxic reactor with the oxygen of the internal recycle. The influence of influent COD/N ratio on the treatment of high-strength ammonium industrial wastewater can be quantified with these results. The influence of COD/N ratio should be one of the main parameters in the design of biological nitrogen removal processes in industrial wastewater treatment.     

白曲霉工程菌TR12循环转化酒精废液研究

在含固体残渣8％的酒精废液中,加入尿素2g／L、玉米浆2mL／L,经接种白曲霉基因工程菌TRl2菌株,在32℃摇床培养70h后,可获得含糖化酶246U／mL和耐酸性α-淀粉酶13．42U／mL的转化液。转化液直接循环利用于无蒸煮酒精发酵配料工序,不仅不影响酒精生产的产量和质量,而且能有效地减轻环境污染压力,节约水资源,降低生产成本。     

Identification of Efficient Denitrifying Bacteria from Tannery Wastewaters in Ethiopia and a Study of the Effects of Chromium III and Sulphide on Their Denitrification Rate

In order to identify potential microorganisms with high denitrifying capacity from tannery wastewaters, 1000 pure cultures of bacterial isolates from Modjo Tannery Pilot and Ethio-tannery wastewater treatment plants (WWTP), in Ethiopia, were investigated. Twenty-eight isolates were selected as efficient denitrifiers. These were Gram-negative rods, oxidase and catalase positive denitrifying organisms. The 28 denitrifying strains were further classified according to their biochemical fingerprints into three different phylogenetic groups (BPT1, BPT2 and BPT3) and seven singles. Isolates B79^T, B11, B12, B15, B28 and B38 belonging to the BPT3 cluster were found to be the most efficient denitrifying bacteria. All phenotypic studies, including cellular fatty acid profiles, showed that the 6 BPT3 isolates were closely related to each other. The 16S rRNA partial sequence analysis of type strain B79^T(CCUG 45880) indicated a sequence similarity of 99% to Brachymonas denitrificans JCM9216 (D14320) in the β-subdivision of proteobacteria. Further studies of the effects of chromium III and sulphide on the six Brachymonas denitrificans strains indicated that denitrification by the isolates were inhibited 50% at concentrations of 54 and 96 mg/l, respectively. The efficient isolates characterized in this study are of great value because of their excellent denitrifying properties and relatively high tolerance to the concentrations of toxic compounds (70 mg chromium/l and 160 mg sulphide/l) prevailing in tannery wastewaters.     

Decolourization and Detoxification of Methyl Red by Aerobic Bacteria from A Wastewater Treatment Plant

Bacterial cultures from a wastewater treatment plant degraded a toxic azo dye (methyl red) by decolourization. Complete decolourization using a mixed-culture was achieved at pH 6, 30 °C within 6 h at 5 mg/l methyl red concentration, and 16 h at 20—30 mg/l. Four bacterial species were isolated that were capable of growth on methyl red as the sole carbon source, and two were identified, namely Vibrio logei and Pseudomonas nitroreducens. The Vibrio species showed the highest methyl red degradation activity at the optimum conditions of pH 6--7, and 30—35 °C. Analysis by NMR showed that previously reported degradation products 2-aminobenzoic acid and N,N-dimethyl-1,4-phenylenediamine were not observed. The decolourized dye was not toxic to a monkey kidney cell line (COS-7) at a concentration of 250 μM. This revised version was published online in July 2006 with corrections to the Cover Date.     

石龙芮在城市生活污水净化中的应用潜力

采用水培技术,研究了石龙芮(Ranunculus sceleratus L.)在净化城市生活污水中的应用潜力.经5 d培养,石龙芮处理组总氮(K-N)、总磷(TP)浓度分别降低到2.93和0.097 6 mg·L-1,总去除率分别达到97.47%和98.44%;氧化还原电位(Eh)迅速提高; pH值得到一定的改善; 浊度迅速下降, 72 h后达到5度. 而对照组K-N、TP浓度分别为35.42和1.27 mg·L-1, 总去除率仅为52.29%和61.31%; 氧化还原电位上升缓慢; 浊度下降缓慢,72 h后仍为 57.8度.结果表明石龙芮在富营养化水体控制及水生生态修复中具有很大的应用潜力.     

厌氧处理低浓度污水颗粒污泥的形成和生物特性研究

用UASB反应器在室温条件下处理模拟低浓度污水,研究了颗粒污泥的形成过程和特性。UASB反应器进水浓度为100～200mgCOD／L,水温为25℃～9℃,60天内形成了成熟的颗粒污泥。颗粒污泥中以丝状菌为主,存在少量球状菌。     

燃料乙醇制造的“零能耗零污染”趋势

酒精蒸馏废液有充足的非淀粉生物质可供沼气转化,沼液营养丰富可作酵母发酵工艺用水。通过酒精高浓度发酵、沼气高效转化、沼气热电联产、差压蒸馏、环形过程工艺等产能、节能、无废技术的研发和集成,将最终完成木薯原料燃料酒精制造向“零能耗、零污染”生产技术的转型。     

Upgrading of facultative waste stabilisation ponds under high organic load

Wastewater treatment using laboratory scale waste stabilisation ponds enriched with activated sludge was studied. After enrichment, the efficiency of these ponds under high organic loading rates (i.e., up to 2800kg CODha^–1day^–1) reached a maximum COD removal rate of 970kg CODha^–1day^–1, which is from 2 to 10 times more than commonly reported values, and suggests that enrichment is an effective method to improve stabilisation ponds.     

Enhanced biological treatment of saline wastewater by using halophilic bacteria

Biological treatment of saline wastewater by conventional activated sludge culture usually results in low removal of chemical oxygen demand (COD) because of plasmolysis of the organisms at high salt concentrations. Since salt removal operations by physicochemical processes before biological treatment are costly, a salt-tolerant organism (Halobacter halobium) was used for effective biological treatment of saline wastewater in this study. Halobacter halobium was used in activated sludge culture for COD removal from saline wastewater (1–5% salt) by fed-batch operation of an aeration tank. Inclusion of Halobacter halobium into activated sludge culture improved the rate and extent of COD removals especially with salt above 2% (w/v).     

Pilot study on the upgrading configuration of UASB-MBBR with two carriers: Treatment effect,sludge reduction and functional microbial identification

Two kinds of biocarriers were adopted and a combined process of “AMC (Anaerobic microorganism carrier)-UASB and PBG (Porous bio-gel)-MBBR” was operated at the pilot scale for the treatment of real textile wastewater. The influence mechanism of the two carriers on the start-up, pollutant removal and sludge reduction were investigated within 118 days of operation. The dominant functional bacteria in anaerobic and aerobic systems were identified by high-throughput sequencing, and the possible ways and related mechanisms of nutrient removal and sludge reduction were analyzed based on the data. 37.0 ± 7.5 % and 53 ± 12.7 % of COD removal efficiencies were achieved in anaerobic system and aerobic system, respectively. Ammonia nitrogen concentration decreased from 20 to 45 to 3.49 ± 0.54 mg/L after treatment. An anaerobe was found to be closely related to color removal, which existed in both anaerobic and aerobic systems, achieving 84.0 % of color removal. With the operation of the system, the sludge yield decreased gradually. The sludge yields of anaerobic and aerobic systems were calculated individually and compared with similar studies. Aging biofilms were characterized to explore the factors associated with biofilm renewal.