城市污水处理工艺综述

介绍了国内外活性污泥废水处理的最新工艺。     

Speciation of chromium in wastewater and sludge by extraction with liquid anion exchanger Amberlite LA-2 and electrothermal atomic absorption spectrometry

A simple, integrated method for the speciation of chromium in wastewater and sewage sludge was developed, utilising liquid anion exchange by Amberlite LA-2 (LAES) and final determination by electrothermal atomic absorption spectrometry (ETAAS). Samples were filtered through a 0.45 μm membrane filter and chromium species were determined in filtered water samples and in sludge on the filters. In the former case (filtrate), total Cr was determined directly by ETAAS, while for the determination of Cr(VI) the filtrate was buffered to pH 6.4, extracted with LAES and Cr(VI) was determined in the organic extract. Cr(III) was determined by the difference. In the latter case (filter), the filters were leached with an alkaline buffer solution (pH 12.7) and the supernatant was subjected to the same extraction procedure. For the determination of total leachable Cr, the filters were subjected to acid leaching with dilute HNO₃ (pH 1) and the supernatant was subjected to ETAAS, after appropriate dilution with water. Then, Cr(III) was determined by the difference. The limits of detection (LOD) were 0.39 and 0.45 μg l⁻¹ for total Cr and Cr(VI), respectively, in the dissolved phase and 2.10 and 0.87 ng g⁻¹ for total Cr and Cr(VI) in the suspended solids. The recoveries of total Cr and Cr(VI) in filtrated wastewater samples and filters were quantitative, ranged from 93 to 106%. The effect of time and temperature of sonication and suspended solids concentration on total Cr and Cr(VI) recovery was studied. No significant difference in recoveries was obtained for sonication temperatures between 30 and 70 °C. However, sonication time equal to or higher than 30 min and concentration of suspended solids equal to or less than 30 mg significantly improved Cr recovery. The ETAAS program for the determination of Cr(VI) in Amberlite/MIBK extract was carefully optimised in the absence of a chemical modifier to avoid memory effects. The developed analytical method was applied for the determination of chromium species in wastewater and suspended solids of a municipal and a lab-scale wastewater treatment plant.     

Monitoring of di-(2-ethylhexyl)phthalate,nonylphenol, nonylphenol ethoxylates,and polychlorinated biphenyls in anaerobic and aerobic sewage sludge by gas chromatography–mass spectrometry

The occurrence of di-(2-ethyhexyl)phthalate (DEHP), nonylphenol and nonyphenol mono- and diethoxylates (NPEs) and seven polychlorinated biphenyl (PCB) congeners in different types of sludge samples is reported. The analysis of these compounds was carried out by sonication-assisted extraction and analytical determination by gas chromatography coupled with a mass spectrometry detector, following a previously described method. The applicability of the method was tested by monitoring the organic pollutants in primary, secondary, mixed, and digested-dehydrated sludge samples from two wastewater treatment plants (WWTPs) based on aerobic and on anaerobic biological stabilization. The occurrence of these compounds in sewage sludge and the influence of sludge stabilization process on the further farmland application of the sludge were evaluated. DEHP and NPEs were detected in all analysed sludge samples from both WWTPs at concentration levels in the range of 22.3–601?mg?kg^?1 and 136–2357?mg?kg^?1 dm (dry matter), respectively. PCBs were detected in all types of sludge analysed from the anaerobic WWTP but was not detected in any sludge sample from the aerobic WWTP. Concentration levels of the sum of the seven PCBs congeners were up to 1.5?mg?kg^?1 dm. The concentration of DEHP, sum of NPEs, and sum of the seven PCB congeners were higher than the limits fixed in the third draft of the future Sludge Directive for land application of sludge in the 67%, 100%, and 11% of samples from the anaerobic WWTP and in the 83%, 92%, and 0% of samples from the aerobic WWTP, respectively.     

污泥中重金属的形态分析及其可浸出性

以自来水厂和污水处理厂的污泥为研究对象,采用Tessier五步法和火焰原子吸收光谱法研究污泥中重金属（Zn、Cu、Cd、Ni、Mn）含量、形态分布以及可浸出性。结果发现,在自来水厂污泥和污水处理厂污泥中重金属总量大小依次为Zn〉Mn〉Ni〉Cu〉Cd,Zn〉Mn〉Cu〉Ni〉Cd,污泥中Zn含量最高,为448.17mg.kg-1;Cd含量最低,为27.17mg.kg-1,超过国家标准,限制了污泥的农用。Tessier形态分析结果表明,污泥中Zn、Cu、Cd主要以稳定态存在;Mn主要以有效态存在,潜在的迁移性和植物毒性最值得关注;Cu浸出率最高,为14.8%,Zn浸出率最低,为0.11%,因此浸出率不仅与金属和污泥的特性有关,而且金属在污泥中赋存的化学形态对其可浸出性也有重要的影响。     

Hydrazine determination in sludge samples by high-performance liquid chromatography

A relatively simple and cost-effective method utilizing HPLC with UV detection was developed to detect and quantify hydrazine in sludge samples. The method was developed primarily for sludge samples, but it can also be applicable to soil and other environmental samples. The hydrazines in the matrices were derivatized to hydrazones with benzaldehyde. The hydrazones were separated using HPLC with an RP C-18 column in an isocratic mode with methanol-water (95:5 v/v) and detected with UV detection at 313 nm. The detection limit (25 microL injection) for the method is 0.02 microg/mL of hydrazine.     

Membrane adsorption bioreactor (MABR) for treating slightly polluted surface water supplies: As compared to membrane bioreactor (MBR)

In this paper, a submerged membrane adsorption bioreactor (MABR) was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5 h. As powdered activated carbon (PAC) was added to the bioreactor at 8 mg/L raw water, the MABR achieved much higher removal efficiency for organic matter in the raw water than the parallel-operated membrane bioreactor (MBR). Moreover, the trans-membrane pressure (TMP) of MABR developed much lower than that of MBR, demonstrating PAC in MABR could mitigate membrane fouling. It was also identified here that the removal of dissolved organic matter (DOM) in MABR was accomplished through the combination of three unit effects: rejection by ultrafiltration (UF) membrane, biodegradation by microorganism, and adsorption by PAC; the last was of great importance. A sludge layer was observed on the membranes surface in both MABR and MBR and PAC particles themselves constituted a part of the cake layer and helped to intercept DOM in the mixed liquor by adsorption in MABR, especially for organic molecules of 5000–500 Da. The UF membrane together with the sludge layer and PAC layer in the MABR was able to reject hydrophobic bases (HoBs), hydrophobic neutrals, hydrophobic acids (HoAs), weakly hydrophobic acids (WHoAs) and hydrophilic matter (HiM) in the mixed liquor by 40.0%, 43.9%, 71.8%, 56.6% and 35.9%, respectively.     

Novel analytical procedures for screening of drug residues in water, waste water, sediment and sludge

Traces of pharmaceuticals are continuously introduced into the aquatic environment mainly by sewage treatment plant effluents. Final data about their impact on the ecosystem are still partly missing. Progress in instrumental analytical chemistry has resulted in the availability of methods that allow a monitoring of these pollutants at ng L⁻¹ levels. In this review the state-of-the-art of residue analysis of pharmaceuticals by chromatographic and electrophoretic techniques is summarized. Improvements in detection limits over the past years have mainly been due to sophisticated mass spectrometric detection techniques. Furthermore, robust sample preparation and preconcentration protocols based on solid-phase extraction and related procedures have contributed significantly to the achievements observed so far. This review also covers several immunochemical approaches which may serve as an inexpensive alternative for quick screening of samples.     

Evaluation of a biological wastewater treatment system combining an OSA process with ultrasound for sludge reduction

Sludge production is an undesirable by-product of biological wastewater treatment. The oxic-settling-anaerobic (OSA) process constitutes one of the most promising techniques for reducing the sludge produced at the treatment plant without negative consequences for its overall performance. In the present study, the OSA process is applied in combination with ultrasound treatment, a lysis technique, in a lab-scale wastewater treatment plant to assess whether sludge reduction is enhanced as a result of mechanical treatment. Reported sludge reductions of 45.72% and 78.56% were obtained for the two regimes of combined treatment tested in this study during two respective stages: UO1 and UO2. During the UO1 stage, the general performance and nutrient removal improved, obtaining 47.28% TN removal versus 21.95% in the conventional stage. However, the performance of the system was seriously damaged during the UO2 stage. Increases in dehydrogenase and protease activities were observed during both stages. The advantages of the combined process are not necessarily economic, but operational, as US treatment acts as contributing factor in the OSA process, inducing mechanisms that lead to sludge reduction in the OSA process and improving performance parameters.     

污泥内层和外层胞外聚合物的三维荧光光谱特性研究

运用三维荧光光谱技术对污泥LB-EPS和TB-EPS的荧光特性进行了研究.实验结果表明,在污泥LB-EPS和TB-EPS中都有三个明显的荧光峰,分别为Peak B(λex/λem=270～280 nm/345～360 nm),Peak C(λex/λem=330～340 nm/410～430 am)和Peak D(λex/λem=390 nm/450～470 nm).其中Peak B为类蛋白荧光(Protein-like)、Peak C为可见区类富里酸荧光(Visible fulvic-like)、Peak D为类腐殖酸荧光(Humic-like).从各荧光峰的荧光强度来分析,LB-EPS和TB-EPS中的主要成分都为类蛋白,然后依次为富里酸和腐殖酸.浓度和pH值对污泥LB-EPS和TB-EPS的三维荧光特性都有很大的影响,但影响程度略有区别,表明作为外层的胞外聚合物,LB-EPS表现出与TB-EPS不全相同的化学结构.     

Poly-β-hydroxybutyrate Production by Fast-Growing Rhizobia Cultivated in Sludge and in Industrial Wastewater

In our study, the potential of producing polyhydroxybutyrate (PHB) by cultivating fast-growing rhizobia (Sinorhizobium meliloti, Rhizobium leguminosarum bv. viciae, R. leguminosarum bv. phaseoli and R. leguminosarum bv. trifolii) in sludge and in industrial wastewater was evaluated. Results confirmed the possibility of using sludge as media for rhizobial growth. During growth, substantial quantity of PHB was accumulated and yields varied depending on the media and rhizobial species. Growing in sludge, PHB production did not exceed 3.7% w/w for all strains at the end of experiment (after 72 h). During the growth of S. meliloti, PHB yield varied and the maximum value reached 7.27% w/w after 60 h, with 1% Total Suspend Solid (TSS) sludge. Alkaline sludge pre-treatment affects rhizobial growth but did not improve the PHB accumulation. While growing S. meliloti in industrial wastewater, the PHB yields varied and the highest value was obtained with slaughterhouse wastewater (10.7% w/w) after 35 h of growth. Therefore, this work shows the potential of exploiting PHB production by rhizobia growing in wastewater or sludge which could be applied to bioplastic industry, and confirms the potential of these recyclable wastes for high production of rhizobial cells useable for legumes inoculants production. This study provides an environmentally sound way of sludge and wastewater management and use in diverse biotechnological applications.