Necessity of Toxicity Assessment in Turkish Industrial Discharges (Examples from Metal and Textile Industry Effluents)

Toxicity of some organic and inorganic chemicals to microorganisms is an important consideration in assessingtheir environmental impact against their economic benefits.Microorganisms play an important role in several environmentalprocesses, both natural and engineered. Some organic and inorganics at toxic levels have been detected in industrial discharges resulting in plant upsets and discharge permit violations. In addition to this, even though in some cases the effluent wastewater does not exceed the discharge limits,the results of toxicity tests show potential toxicity. Toxicityknowledge of effluents can benefit treatment plant operators inoptimising plant operation, setting pre-treatment standards, and protecting receiving water quality and in establishing sewer discharge permits to safeguard the plant. In the Turkish regulations only toxicity dilution factor (TDF) with fish is part of the toxicity monitoring program of permissible wastewater discharge. In various countries, laboratory studiesinvolving the use of different organisms and protocol for toxicity assessment was conducted involving a number of discharges.In this study, it was aimed to investigate the acute toxicity of textile and metal industry wastewaters by traditional and enrichment toxicity tests and emphasize the importance of toxicity tests in wastewater discharge regulations. The enrichment toxicity tests are novel applications and give anidea whether there is potential toxicity or growth limiting and stimulation conditions. Different organisms were used suchas bacteria (Floc and Coliform bacteria) algae (Chlorella sp.), fish (Lepistes sp.) and protozoan (Vorticella sp.) to represent four tropic levels. The textile industry results showed acute toxicity for at least one organism in 8 out of 23 effluent samples. Acute toxicity for at least two organisms in 7 out of 23 effluent sampling was observed for the metal industry. The toxicity test results were assessed with chemical analyses such as COD, BOD, color and heavy metals. It was observed that the toxicity of the effluents could not be explained by using physicochemical analyses in 5 cases for metal and 4 cases for the textile industries. The results clearly showed that the useof bioassay tests produce additional information about the toxicity potential of industrial discharges and effluents.     

Quantitative Analyses of Pollution-Indicator and Pathogenic Bacteria in Mumbai Waters from Ballast Water Exchange Perspective

As large numbers of ships either take in ballast from or discharge their ballast into the Mumbai Harbor region, it is pertinent to quantify microorganisms of health concerns and suggest on the suitability of water for ballasting purposes. To meet with this main aim, a selected set of general and pathogenic bacterial groups and their seasonal variations were studied from the Mumbai Harbor area. Sampling was carried out during postmonsoon (November 2001), pre-monsoon (April 2002) and monsoon (October 2002) periods. We quantified total coliforms and eight other groups of known human pathogenic bacteria from water, sediment, marine plant and animal samples collected in and around Mumbai Harbor. When compared with similar studies from other parts/harbors of the world, the Mumbai Harbor area has over 100-times higher levels of coliforms. The serotypes of Escherichia coli O157 and Shigella-Alkaligens Dispar group were abundant throughout the year. Even Vibrio cholerae, V. parahaemolyticus, Salmonella spp., campylobacters and aeromonads were present in large numbers. This comprehensive study, conducted with a view to quantify these bacterial groups and to evaluate the suitability of these waters for ballasting purposes, clearly suggests that both ballasting and deballasting be avoided in this region and alternative procedures should be developed for treating/handling ballast water.     

Characterization of Sulfate Reducing Bacteria Isolated from Cooling Towers

In this study, the occurrence and metabolic capacities of sulfate reducing bacteria (SRB) were studied in 36 water samples taken from cooling towers of 30 different buildings, such as hotels and business centres in Istanbul. SRB were present in 14 cooling towers out of 30 (46.6%) buildings and while the lowest concentration of SRB was 10 cells/mL, the highest concentration was determined as 10⁴ cells/mL. After the distribution of SRB within cooling towers was determined, several strains of SRB were isolated and characterized metabolically. The isolated strains were composed of vibroid cells, growing anaerobically by using sulfate as electron acceptor and lactate or pyruvate as electron donor. They could be related to the genus Desulfovibrio. In addition, the recorded temperature of water samples was between 12 and 33C and a significant relationship between the number of SRB and the water temperatures was not found.     

Molecular approaches to microbiological monitoring: fecal source detection

Molecular methods are useful both to monitor natural communities of bacteria, and to track specific bacterial markers in complex environments. Length-heterogeneity polymerase chain reaction (LH-PCR) and terminal restriction fragment length polymorphism (T-RFLP) of 16S rDNAs discriminate among 16S rRNA genes based on length polymorphisms of their PCR products. With these methods, we developed an alternative indicator that distinguishes the source of fecal pollution in water. We amplify 16S rRNA gene fragments from the fecal anaerobic genus Bacteroides with specific primers. Because Bacteroides normally resides in gut habitats, its presence in water indicates fecal pollution. Molecular detection circumvents the complexities of growing anaerobic bacteria. We identified Bacteroides LH-PCR and T-RFLP ribosomal DNA markers unique to either ruminant or human feces. The same unique fecal markers were recovered from polluted natural waters. We cloned and sequenced the unique markers; marker sequences were used to design specific PCR primers that reliably distinguish human from ruminant sources of fecal contamination. Primers for more species are under development. This approach is more sensitive than fecal coliform assays, is comparable in complexity to standard food safety and public health diagnostic tests, and lends itself to automation and high-throughput. Thus molecular genetic markers for fecal anaerobic bacteria hold promise for monitoring bacterial pollution and water quality.     

Effect of Common Pesticides Used in the Niger Delta Basin of Southern Nigeria on Soil Microbial Populations

The effects of eleven pesticides on the populations of bacteria, actinomycetes, fungi and protozoa was investigated by treating a garden soil with their recommended rates. The microbial populations were estimated using the standard plate-count technique. Of the ll pesticides investigated, phenylmercuric acetate (agrosan) at 50 g g^-1 inhibited bacterial density the most, i.e. from 4,600,000 to 220 cells g^-1. The pesticides were Pentachloronitrobenzene (PCNB), tetramethylmethylthiuram disulphide (thiram),1- naphthylmethylcarbamate (Vetox 85), 1,2,3,4,5,6-hexachlorocyclohexane (Gammalin 20), phenylmercuric acetate (Agrosan), tetrachloroterephthalic acid (Dacthal), 4-nitrophenyl –2-nitro-4-trifluoromethylphenyl ether (Preforan), 2-ethyl-6-methyl –N-2-methoxy –1-methyl ethyl-chloroacetanide (Dual), Benlate, Brestan and Gramoxone. Pentachloronitrobenzene (PCNB) at 240,000 g g^-1 reduced bacterial population from 4,600,000 to 2,100 cells g^-1, whereas tetramethylthiuram disulphide (thiram) at 100 g g^-1 suppressed it by 2 log orders of magnitude. Soil application of 1-naphthylmethylcarbamate (Vetox 85) at 100 g g^-1 and 1,2,3,4,5,6,-hexachlorocyclohexane (Gamalin 20) at 1,300 g g^-1 repressed the bacterial numbers by 2 log orders of magnitude each. Pentachloronitrobenzene reduced the actinomycetes density from 340,000 to 320 cells g^-1 and completely eliminated all fungal and protozoan propagules from the soil. The Gammalin 20 completely wiped out all the fungi, whereas phenylmercuric acetate totally eliminated all the protozoa and reduced the fungal population from 34,000 to 60 cells g^-1. In general, protozoa and fungi were more susceptible to fungicides than bacteria and actinomycetes. Pentachloronitrobenzene, 1,2,3,4,5,6,-hexachlorocyclohexane and phenylmercuric acetate were toxic particularly to soil microorganisms, whereas the herbicides dacthal, Preforan and Dual were quite harmless in soil at application rates of 0.1, 0.06 and 0.02 g g^-1 respectively.     

Copper, Copper Mining Effluents and Grazing as Potential Determinants of Algal Abundance and Diversity in Northern Chile

We experimentally tested threealternative hypotheses to explain the low algaldiversity and abundance in an intertidal zonereceiving the effluents of the copper mine El Salvadorin northern Chile. Our results demonstrated thatalgae were able to grow at the levels of dissolvedcopper detected in coastal waters of the area. Duringthe assays, growth and regeneration in several red,green and brown adult algae and juvenile Lessonia nigrescens were normal at copper levels of150 g L^-1 or, in some cases, higher. Wealso found that the coastal sea water mixed with theeffluent was not lethal to algae, although in somecases minor effects on growth were detected. Theseresults indicate that today's low algal diversity andabundance can not be explained by the current copperlevels in the area nor by the effect of the effluent.Exclusion of grazers, however, resulted in a fastcolonization by various algal species. This, togetherwith atypically high grazer density at the areas underthe influence of the effluent, strongly suggests thatherbivory, a factor not directly related to the miningoperation, is likely to be responsible for the lowalgal diversity and abundance in the studied locality.     

Allelochemicals and allelopathy from microorganisms in wheat rhizosphers

Allelochemicals from fungi and bacteria in wheat rhizosphere,as well as their allelopathic effects on wheat and maize have been conducted.Fungi and bacteria were incubated at temperature 28-30℃.The extracts were tested for bioassay.Some samples identified to be responsible for allelopathy have been determined by GC-MS.Some chemicals identified were selected to test again their bioactivity.The results showed that acidic extracts were more toxic to germination of wheat and maize seeds(statistic significant difference P<0.01 or P<0.05)and basic extracts were less toxic and stimulated effects on germination in some cases.A good relationship has been observed between the data of chemical analysis and bioassay. A wide variety of chemicals such as phenolic acids,organic acids,aldehydes,alcohol,ketones,nitrogen-containing chemicals,were identified by GC-MS.Some phenols and organic acids were identified to be inhibit and nitrogens-containing compounds were to be stimulate to germination of seeds and extension of root and shoot of wheat and maize.     

Long- and short-chain AHLs affect AOA and AOB microbial community composition and ammonia oxidation rate in activated sludge

Quorum sensing (QS) regulation of the composition of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) communities and functions in wastewater treatment was investigated. Specifically, we explored the role of N-acyl-l-homoserine lactones (AHLs) in microbial community dynamics in activated sludge. On average, the specific ammonia-oxidising-rate increased from 1.6 to 2.8?mg?NH₄⁺-N/g?MLSS/hr after treatment with long-chain AHLs for 16?days, and the addition of AHLs to sludge resulted in an increased number of AOA/AOB amoA genes. Significant differences were observed in the AOA communities of control and AHL-treated cultures, but not the AOB community. Furthermore, the dominant functional AOA strains of the Crenarchaeota altered their ecological niche in response to AHL addition. These results provide evidence that AHLs play an important role in mediating AOA/AOB microbial community parameters and demonstrate the potential for application of QS to the regulation of nitrogen compound metabolism in wastewater treatment.     

黄河三角洲附近海域浮游动物多样性研究

以文献资料和定性调查相结合的方法，综合分析了黄河三角洲附近海域浮游动物物种多样性；以定量调查结果，探讨了浮游动物多样度以及与均度、单纯度之间的关系。结果表明： 该海域浮游动物物种占中国海的５－７ ％ ，占渤海的５１－７％ ；浮游动物多样度在０－１０ ～２－２８ 之间，均度在０－０２～０－９７ 之间，单纯度在０－１４ ～０－９９ 之间；多样度与均度呈显著的正相关，与单纯度呈显著的负相关。     

Influence of carbon source and temperature on the denitrifying phosphorus removal process

To supply the valuable operating parameters for the popular usage of the new denitrifying phosphors removal process, it is essential to study the dominant biochemical reactions and the characteristics of denitrifying phosphorus removing bacteria (DPB). Thus, parallel batch experiments using DPB sludge were carried out to assess the effect of substrates (sewage, HAc, and endogenous carbon source) on denitrifying dephosphorus removal efficiency in this study. The results showed that the initial specific phosphorus release rate increased with the high concentration of the short-chain volatile fatty acids ratio in the influent, and sufficient phosphorus was released by DPB. This improved the subsequent denitrification and phosphorus uptake efficiency. The specific endogenous denitrification mainly relies on the internal carbon source (PHB) stored by poly-P bacteria. Denitrifying phosphorus removing bacteria were very hungry when the internal PHB was consumed. Consequently, the specific endogenous denitrification rate was low and the phosphorus uptake did not happen. On the other hand, in the experiment, the denitrifying phosphorus removal performance under two temperature conditions (8–10°C and 25–26°C) was also investigated and analyzed. It was found that the lower temperature decreased the specific phosphorus release and uptake rate, but did not inhibit the denitrifying phosphorus removal completely. Therefore, the negative influence of the low temperature on the overall phosphorus removal was not significant. Translated from Acta Scientiae Circumstantiae, 2006, 26 (2): 186–192 [译自: 环境科学学报]