Treatment of high-strength pet food wastewater using two-stage membrane bioreactors.

A two-stage membrane bioreactor was used to treat dissolved-air-flotation pretreated, high-strength pet food wastewater characterized by oil and grease concentrations of 50 000 to 82 000 mg/L and total chemical oxygen demand (COD) and five-day biochemical oxygen demand (BOD5) concentrations of 100 000 and 80 000 mg/L, respectively, to meet stringent surface discharge criteria (i.e., BOD5, total suspended solids [TSS], and ammonium-nitrogen [NH4(+)-N] of < 10 mg/L at an overall hydraulic retention time of 6.3 days). Organic contaminants were removed primarily in the first stage, followed by almost complete removal of ammonia in the second stage. Despite a rise in poorly biodegradable COD in the second stage, overall removal of TSS, BOD5, COD, and ammonia was 100, 99.9, 95.2, and 99.7%, respectively, thus readily achieving the required criteria. Consistent nitrite accumulation over a period of more than 100 days, even at dissolved oxygen concentrations of more than 2.5 mg/L, was remarkable. A residual alkalinity requirement for nitrification was quantified. Membrane performance was extensively studied in this work.     

Seasonal performance of an outdoor constructed wetland for graywater treatment in a temperate climate

The seasonal treatment efficiency of a pilot-scale constructed wetland system located outdoors in a semi-arid, temperate climate was evaluated for graywater in a comprehensive, 1-year study. The system consisted of two wetland beds in series--a free water surface bed followed by a subsurface flow bed. Water quality monitoring evaluated organics, solids, nutrients, microbials, and surfactants. The results showed that the wetland substantially reduced graywater constituents during fall, spring, and summer, including biochemical oxygen demand (BOD) (92%), total nitrogen (85%), total phosphorus (78%), total suspended solids (TSS) (73%), linear alkylbenzene sulfonate (LAS) surfactants (94%), and E. coli (1.7 orders of magnitude). Except for TSS, lower removals of graywater constituents were noted in winter--BOD (78%), total nitrogen (64%), total phosphorus (65%), LAS (87%), and E. coli (1.0 order), indicating that, although wetland treatment slowed during the winter, the system remained active, even when the average water temperature was 5.2 +/- 4.5 degrees C.     

不同pH条件下酵母菌处理高含油废水的研究

在使用混合酵母菌菌株处理高浓度含油废水中，研究了序批式反应器（SBR）内酵母菌在不同起始pH条件下对废水的处理效果。通过与pH中性或碱性条件比较发现，pH4～5的条件在酵母菌的发泡抑制、菌体生长以及COD／油去除等方面均显示出更好的效果，pH5是系统运行的最佳条件。长达100d的SBR连续运行试验表明，系统可以在pH=5条件下长期、稳定运行。     

Low-pressure catalytic wet-air oxidation of a high-strength industrial wastewater using Fenton's reagent.

Wastewater from the Afyon Alkaloids Factory (Afyon, Turkey) was subjected to low-pressure catalytic wet-air oxidation (CWAO) using Fenton's reagent, and the optimal reaction conditions were investigated. The CWAO using Fenton's reagent was applied to the factory effluent, diluted factory effluent, and aerobically pretreated wastewater. To find the optimum quantities of reagents, ferrous iron (Fe(+2))-to-substrate ratios of 1:10, 1:25, and 1:50 and hydrogen peroxide (H2O2)-to-Fe(+2) ratios of 1, 5, and 10 were investigated, and the treatment was carried out at different temperatures. High chemical oxygen demand (COD) removals were obtained at 50 degrees C, with the Fe(+2)-to-substrate ratio range between 1:10 and 1:25. The change in H2O2-to-Fe(+2) ratios did not cause any considerable effect. Also, the percentages of COD removals were nearly the same, so the ratio H2O2:Fe(+2):1 is recommended. Aerobic pretreatment seems to be effective. On the other hand, no enhancement was observed in the case of the diluted wastewater.     

Kinetics and stoichiometry of aerobic sulfide oxidation in wastewater from sewers-effects of pH and temperature.

Kinetics and stoichiometry of aerobic chemical and biological sulfide oxidation in wastewater from sewer networks were studied. In this respect, the effects of temperature and pH were investigated in the ranges 10 to 20 degrees C and 5 to 9, respectively. The temperature dependency of sulfide oxidation kinetics was described using an Arrhenius relationship. The effect of pH on the rate of chemical sulfide oxidation is related to the dissociation of hydrogen sulfide (H2S) to hydrogen sulfide ion (HS(-)), with HS(-) being more readily oxidized than H2S. Biological sulfide oxidation exhibited the highest rates at ambient wastewater pH, and the reaction was inhibited at both low and high pH values. Chemical sulfide oxidation was found to produce thiosulfate and sulfate, while elemental sulfur was the main product of biological sulfide oxidation. Based on the investigations, general rate equations and stoichiometric constants were determined, enabling the processes to be incorporated to conceptual sewer process models.     

一株反硝化细菌的分离鉴定及脱氮能力

本研究从水产养殖环境中分离出39株反硝化细菌,并从中筛选出具有较强反硝化能力的菌株DB-33,对其脱氮能力测定的结果表明,在培养基中亚硝酸盐氮浓度高达54．16mg／L,硝酸盐氮浓度高达306．91mg／L时,DB-33菌株对其去除率均达99％以上,且在去除过程中氨氮不累积;在模拟养殖水体中,DB-33可将亚硝酸盐氮和硝酸盐氮分别在24h和第3天彻底去除,对氨氮48h的去除率也可达51．52％。通过形态学特性和生理生化分析以及16SrDNA基因序列分析,菌株DB-33初步鉴定为施氏假单胞菌（Pseudomonasstutzeri）。     

Integrated catalytic wet air oxidation and aerobic biological treatment in a municipal WWTP of a high-strength o-cresol wastewater

This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass.     

Metal stoichiometry in predicting Cd and Cu toxicity to a freshwater green alga Chlamydomonas reinhardtii

In this study, we quantified the accumulation and toxicity of cadmium and copper in a freshwater green alga, Chlamydomonas reinhardtii, under different phosphate conditions. The accumulated Cd and Cu concentrations increased significantly with increasing ambient P concentrations and free metal ion concentrations. The metal:P ratio remained independent of the ambient P concentration. For the three pulse-amplitude-modulated parameters, the median inhibition concentrations were 1.5-1.6x and 2.0x higher, but the medium inhibition cellular quota was 2.2x and 1.2x lower for cells maintained at 0.1 microM P than for cells maintained at 10 microM P for Cd and Cu, respectively. Furthermore, the difference in metal toxicity decreased (for Cd) or disappeared (for Cu) when the toxicity was expressed by the metal:P ratio in the cells, indicating that the stoichiometry of metals and P can be better used to predict the toxicity of metals. It is necessary to consider the stoichiometry of metals in predicting metal toxicity in phytoplankton.     

Treatment of landfill leachate by irrigation of willow coppice - Plant response and treatment efficiency

Landfill leachates usually need to be treated before discharged, and using soil-plant systems for this has gained substantial interest in Sweden and in the UK. A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix). Two willow varieties were tested and four irrigation regimes in sixteen 400-m² plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (≤2160 kg N/ha), chloride (≤8600 kg Cl/ha) and other elements. Mean annual growth was 1.5, 9.8 and 12.6 tonnes DM/ha during years 1-3. For one of two willow varieties tested, relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied.     

一株高效降酚菌的分离鉴定及降酚特性研究

以苯酚为唯一碳源,采用逐量分批的方法从被酚类物质污染的土壤中驯化、筛选、分离降酚菌,利用形态学、培养特性、生理生化反应以及分子手段鉴定所得菌株,研究了该菌株生长与降酚的关系以及其降酚能力,并设计引物检测降酚酶基因。结果表明,获得的一株高效降酚菌GDYW-0027经鉴定为不动杆菌属(Acinetobacter),它的生长速率与苯酚的降解速率基本同步,48h内对高质量浓度(2.2g/L)苯酚的降解率为86.73%;在菌株GDYW-0027中检测到苯酚羟化酶及邻苯二酚2,3双加氧酶基因片段,推测其采用间位开环方式打开苯环。     

Nutrient stoichiometry in Sphagnum along a nitrogen deposition gradient in highly polluted region of Central-East Europe

We investigated the variation of N:P and N:K ratio in ombrotrophic Sphagnum plants along a gradient of atmospheric N deposition from 1 to 2.5 g m⁻² year⁻¹ in Central-East Europe. The N:P and N:K ratio in Sphagnum capitula increased significantly along the N deposition gradient. Sphagnum species from the Cuspidata section were characterised by significantly lower ratios at low N deposition. When we compared the observed N:P ratios in Sphagnum plants with the values reported in a previous European-wide study, we found a correspondence in nutrient stoichiometry only for a few bogs: higher P concentration in Sphagnum capitula caused a lower N:P ratio in most of the study bogs so that Sphagnum plants still seem N-limited despite their N saturation. Interaction between summer water table decrease and aerial liming of surrounding forests is proposed as an explanation for this discrepancy. Local forestry practice interacting with climate thus alter N:P stoichiometry of Sphagnum along the N deposition gradient.     

微气泡曝气O3／H2O2处理RO浓水的效能及影响因素

采用O3／H2O2高级氧化工艺处理炼油厂反渗透（RO）浓水,用溶气泵加压溶气并产生微气泡强化传质,确定装置运行条件,考察气体中臭氧浓度、O3／H2O2初始摩尔比、pH和温度对O3／H2O2处理RO浓水效果的影响,并对RO浓水处理效能进行研究。结果表明,随着气体中臭氧浓度的增加,COD的去除率基本呈线性增加;加入适当量H,0,能提高臭氧氧化RO浓水的效果,O3／H2O2初始摩尔比在0～0．8范围内,COD的去除率先增加后下降,O3／H2O2初始摩尔比为O．5时COD去除率最大;pH从6．84增加到9．01,COD去除率逐渐增大,pH为10．03时COD去除率反而降低;在14～28℃范围内,温度低时,升高温度COD去除率增加较大,温度较高时,升高温度对COD去除率的影响较小。为考察该工艺的稳定性,在H：0：／0,初始摩尔比为O．5、溶液pH为8～9、臭氧浓度为80～100mg／L、温度为10-28℃条件下,对COD为90～140mg／L的RO浓水氧化处理4～10h,出水COD维持在39．9～49．9mg／L,达到《城镇污水处理厂污染物排放标准（GB18918—2002）》中的一级A标准;去除1gCOD消耗031．4～3．3g,消耗0,与H,02的总氧量为2．2～4．4g。     

高浓度难降解乳化废水湿式氧化动力学

以高浓度难降解乳化废水为处理对象,在2L高压间歇反应釜中,研究了温度对湿式氧化的影响和动力学特征。结果表明,升高温度不但促使反应向直接氧化成终产物方向偏移,也使中间产物加速氧化,使CODcr和TOC去除率显著提高,220℃时可分别达86．4％和79．5％;通用动力学模型能较好预测湿式氧化过程,并得到基于CODcr的表观活化能：有机物直接氧化成终产物为6．19kJ／mol;中间产物氧化成终产物为24．47kJ／mol。     

高浓度苯酚降解菌Candida tropicalis Z-04的鉴定及其对苯酚降解条件的优化

从降解苯酚的好氧颗粒污泥中筛选出一株苯酚降解菌,该菌株最高可耐受2.0 g/L的苯酚.依据形态特征和内源转录间隔区(ITS)的核酸序列分析,将该菌株鉴定为热带假丝酵母菌(Candida tropicalis),并命名为Candida tropicalis Z-04.采用中心复合设计(CCD)法对Candida trop...     

Numerical analysis on a novel CGPFs for improving NOx conversion efficiency and particulate combustion efficiency to reduce exhaust pollutant emissions

Environmental Science and Pollution Research - Improving the NOx conversion efficiency and particulate combustion efficiency under cold-start conditions (low-temperature conditions) is still the...     

Trapping efficiency of selected adsorbents for various airborne pesticides.

A study was conducted to compare the efficiency of five adsorbents used by government and private laboratories to collect airborne pesticides. Six pesticides, acephate, chlordane, chlorpyrifos, diazinon, heptachlor, and propoxur, were vaporized in a closed system and collected on each of the adsorbents, Chromosorb 102, ORBO 42, ORBO 44 (chlordane and heptachlor only), polyurethane foam (PUF) or Tenax GC, by drawing 250 L of air through the adsorbent. There were no differences in collection efficiency of the five pesticides on Chromosorb 102, ORBO's 42/44, and PUF. The efficiency with Tenax was somewhat less with several of the pesticides.     

The reactions of paraquat and divalent metal ions with humic acid: Factors influencing stoichiometry 2

Abstract

Laurentide humic acid has been titrated with paraquat and with selected divalent metal ions. In some cases, the humic acid was spiked with one cation before titration with another one. Several equivalence points were determined for the binding of the divalent cations, including paraquat. Three equivalence points agreed well with values predicted from the acidic properties of the humic acid. Eight independent experiments gave nine replicate values for an equivalence point that corresponds to 79.2 mole % of the total pairs of carboxyl groups. It is postulated that this represents a large molecular weight or structural fraction of the humic acid. The remaining 20.8 mole % can either bind one divalent cation to two carboxylate anions or bind one divalent cation to one carboxylate anion, with another anion providing for charge balance. Aggregation ‐ disaggregation and dissolution ‐precipitation phenomena may determine which case prevails, and they in turn are sensitive to the chemical compositions of samples. It should be possible to develop analytical chemical methods for characterizing the stoichiometric properties of humic acid samples.     

Treatment and detoxification of a sanitary landfill leachate

The leachate from an old sanitary landfill (Gramacho Metropolitan Landfill, Rio de Janeiro) was characterized and submitted to coagulation and flocculation treatment followed by ozonation and ammonia stripping. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and TOC), ammonium nitrogen and metals. Detoxification was assessed by determining acute toxicity, using the following organisms: Vibrio fisheri, Daphnia similis, Artemia salina and Brachydanio rerio. Membrane fractionation was employed to infer the range of molecular masses of the pollutants found in the effluent, as well as the toxicity associated to these fractions. Of the techniques under investigation, coagulation and flocculation followed by ammonia stripping were the most effective for toxicity and ammonium nitrogen removal. Membrane fractionation was effective for COD removal; however, acute toxicity was almost the same in all the fractionated samples. Ozonation was moderately effective for COD removal, but significant toxicity removal was only attained when high ozone doses were used.     

高速泳动床对村镇微污染水体的预处理效果

利用高速泳动床反应器作为预处理装置处理村镇微污染水体,出水进入组合人工湿地。结果表明,实验阶段高速泳动床在HRT为1.2 h时,尽管泳动床进水各污染物浓度较低,但反应器对COD、TN和TP仍具有较明显（P〈0.05）的去除效果,平均去除率分别为11.3%、14.6%和25.8%。高速泳动床反应器对氨氮去除效果尤为明显,去除率达到46.9%。此外,高速泳动床反应器内硝化作用较强,出水中硝态氮含量平均增加率为45.5%,弥补了后续人工湿地硝化作用不强、除氨氮效果不佳的缺点。