Use of Chemotaxonomy To Study the Influence of Benzalkonium Chloride on Bacterial Populations in Biodegradation Testing

Contradictory results are reported for the behaviour of quaternary ammonium compounds (QACs) in sewage treatment plants (STPs). QACs may sorb onto activated sludge. Only little information is available with respect to effects of QACs against bacteria in STPs. Only 5 to 15 % of bacteria present in sewage sludge can be detected by means of culture dependent microbiological methods. The shift of the bacterial populations due to effects of test compounds have not been studied up to now with culture independent methods. The microbial populations shift was studied in situ using culture independent chemotaxonomy profiling ubiquinones and polyamines. Additionally, toxic effects of QACs against bacteria present in the test vessels of the Zahn‐Wellens test (OECD 302 B) were assessed with a toxicity control in the test. The ubiquinone profiles representing changes in Gram‐negative populations mainly showed that the activated sludge was affected only in test vessels containing benzalkonium chloride. According to chemotaxonomy Acinetobacter or/and some members of Pseudomonas spp. have been selected by benzalkonium chloride after some adaptation period (8 to 12 days).     

Treatment of Malting Wastewater in a Granular Sludge Sequencing Batch Reactor (SBR)

Aerobic granular sludge was successfully cultivated in a sequencing batch reactor (SBR) treating wastewater from the malting process with a high content of particulate organic matter. At an organic loading rate of 3.2 kg/(m³ d) COD_total and an influent particle concentration of 0.95 g/L MLSS an average removal of 50% in COD_total and 80% in COD_dissolved could be achieved. A comparison of granular and flocculent sludge grown under the same operating conditions showed no significant difference in removal efficiency although granules exhibited a higher metabolic activity in terms of specific oxygen uptake rate (r_{O2, X}). Two distinct mechanisms of particle removal were observed for granular sludge: during initial granule formation, particles were incorporated into the biofilm matrix. For mature granules, a high level of protozoa growth on the granule surface accounted for the ability to remove particulate COD. Combined evaluation of the development in MLSS content and sludge bed settling rate (i.e., mean derivative of the normalized sludge volume) was found to be an adequate method for monitoring the characteristic settling properties of a granulizing sludge bed. By means of this method, a distinct substrate gradient out of several operating conditions was concluded to have the biggest impact on the formation of aerobic granular sludge.     

城市污水处理厂污泥利用现状及潜在环境问题

根据国家环保总局要求,在2010年前全国主要城市的污水处理率要达到70%,这将使我国的水环境得到明显改善,另一方面也带来了污泥的处置和利用问题.污泥是一种优质的有机肥料,有选择地控制使用,既可满足作物生长对养分的需要,又可培育土壤.符合污泥固废“减量化”和“资源化”的处置要求.     

砖瓦企业综合利用河道疏浚淤泥研究

介绍了砖瓦企业利用河道疏浚淤泥替代粘土的新思路。通过取样分析和对比研究,证实这是一条值得推广应用的资源循环利用的有效途径。     

城市污泥接种堆置处理对重金属的形态及其生物有效性的影响

污泥堆肥化后的土地利用是污泥处理处置的重要方法之一。经过对荆马河底泥接种堆置处理,揭示出污泥中重金属的形态发生明显的变化。荆马河底泥中的重金属污染物主要以结合态和残渣态的形式存在,水溶态和交换态的量很小,经接种堆置处理后,水溶态和交换态量大幅削减,结合态和残渣态量有所增加,总量变化不大,生物学方法和化学方法测定都表明,处理后的底泥生物毒性有明显降低,重金属的生物有效性降低。     

Chlorphenole und Nonylphenole in Klärschlämmen. Teil II: Hat die Belastung mit Pentachlorphenol und Nonylphenolen abgenommen?

Chlorophenols and Nonylphenols in Sewage Sludges. Part II: Did Contents of Pentachlorophenol and Nonylphenols Reduce? Sewage sludges were analyzed for pentachlorophenol and isomeric 4-nonylphenols. These environmental pollutants are not regulated by the German sewage sludge regulations (Klärschlammverordnung) but are subsequently controlled by the pentachlorophenol prohibition ordinance and the industry’s voluntary declaration of renouncing the use of alkylphenol ethoxylates. The samples analyzed originated from sewage treatment plants in the state Rheinland-Pfalz from 1994 till 1995. The analytical results are presented graphically by histograms and numerically by quantiles (median, 90%-percentile).The results are compared to those we formerly obtained from all West German states from 1987 till 1989. To verify the statistical significance of median differences, we used the Wilcoxon test suitable for non parametric data distributions. All histograms show non symmetrical frequency distributions. In almost all 101 analyzed samples, pentachlorophenol was found at a median of 19 μg/kg related to dry matter (d.m.) and a 90%-percentile of 86 μg/kg related to d.m. Compared with the past, there seems to be a tendency to lower values which, however, cannot be proved statistically. In almost all sewage sludge samples, nonylphenols could be found at a median of 4.6 mg/kg related to d.m. and a 90%-percentile of 24.8 mg/kg. In contrast to the past, these values are very low; nonylphenols in sewage sludges have significantly reduced. This may be a hint that the industry’s voluntary dec-laration has been taken seriously.