The environmental issues caused by the municipal solid waste disposal are becoming a worldwide concern.
Methods
We studied the situations both domestically and abroad by the strategic environmental assessment (SEA) approach and also conducted comprehensive evaluations of garbage disposal in Changchun City.
Results
On the basis of this study, we found that SEA is of great importance in the municipal solid waste disposal. Moreover, with the rapid socioeconomic development of Changchun City, municipal solid waste production increases on an annual basis, and thus, good waste management planning is of great significance.
Conclusions
Considering the situation of the economic development of Changchun City, garbage disposal was handled mainly in the major sanitary landfills with appropriate use of incineration technology. This plan is environmentally friendly at a relatively high degree and has met the requirements of minimum investment. It also takes into account the requirements of the development of incineration technology. Regarding environmental pollution in terms of groundwater pollution and atmospheric pollution, this plan is a feasible one by meeting various requirements with low environmental impact among the three plans discussed in this study. 相似文献
The role of water in the transmission of infectious diseases is well defined; it may act as a reservoir of different types of pathogens. Enteric viruses can survive and persist for a long time in water, maintaining infectivity in many instances. This suggests the need to include virus detection in the evaluation of the microbiological quality of waters.
Methods
In this study, enteric viruses (enteroviruses and hepatitis A virus (HAV)) were investigated by RT-PCR and coliphages (known as indicators of viral contamination) were enumerated with the double-layer technique agar in effluents and sewage sludge from three Tunisian wastewater treatment plants.
Results and discussion
The molecular detection of enteric viruses revealed 7.7% of positive activated sludge samples for enteroviruses. None of the samples was positive for HAV. Molecular virus detection threshold was estimated to be 103?PFU/100?ml. All samples contained high concentrations of coliphages except those of dry sludge. Reductions in the concentrations of bacteriophages attained by the wastewater treatment plants are of the order of magnitude as reductions described elsewhere. Peak concentrations in raw wastewater were associated with winter rains and suspended materials rate in analysed samples. Our data which is the first in North Africa showed that similar trends of coliphages distribution to other studies in other countries.
Conclusion
No clear correlation between studied enteric viruses and coliphages concentration was proved. Coliphages abundance in collected samples should raise concerns about human enteric viruses transmission as these residues are reused in agricultural fields. 相似文献
The presence of heavy metals in wastewater is one of the main causes of water and soil pollution. The aim of the present study was to investigate the removal of Cd, Cu, Pb, Hg, Mn, Cr and Zn in urban effluent by a biological wastewater treatment, as well as to quantify the levels of As, Be, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn, Tl, V and Zn in dewatering sludge from the Biological Wastewater Treatment Plant to Ribeirão Preto (RP-BWTP), Brazil.
Materials and Methods
Concentrations of Cd, Cr, Cu, Mn and Pb in wastewater and those of Ni in sludge were determined by atomic absorption spectrophotometry with graphite furnace atomization. Mercury concentrations in wastewater were measured by hydride generation atomic spectrophotometry, and Zn levels were determined by atomic absorption spectrophotometry using acetylene flame. In sludge, the levels of As, Be, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Sn, Tl, V and Zn were determined by inductively coupled plasma-mass spectrometry.
Results
The percentages of removal efficiency (RE) were the following: Hg 61.5%, Cd 60.0%, Zn 44.9%, Cu 44.2%, PB 39.7%, Cr 16,5% and Mn 10.4%. In turn, the mean concentrations (mg/kg) of metals in dewatering sludge followed this increasing order: Tl (<0.03), Hg (0.31), Be (0.43), As (1.14), Cd (1.34), V (59.2), Pb (132.1), Sn (166.1), Cr (195.0), Mn (208.1), Ni (239.4), Cu (391.7), Zn (864.4) and Fe (20537).
Discussion
The relationship between metal levels in untreated wastewater, as well as the removal efficiency are in agreement with previous data from various investigators, It is important to note that metal removal efficiency is not only affected by metal ion species and concentration, but also by other conditions such as operating parameters, physical, chemical, and biological factors.
Conclusions
Metal values recorded for treated wastewater and sludge were within the maximum permitted levels established by the Environmental Sanitation Company (CETESB), São Paulo, Brazil.
Recommendations
There is an urgent need for the authorities who are responsible for legislation on sludge uses in agriculture of establishing safety levels for As, Be, Hg, Sn, Tl and V.
Perspectives
According to the current metal levels, RP-BWTP sludge might be used for agriculture purposes. However, for an environmentally safe use of sewage sludge, further studies including systematic monitoring are recommended. Annual metal concentrations and predicted variations of those elements in the sludge should be monitored.
It is well recognized that management of wastewater and sludge is a critical environmental issue in many countries. Wastewater treatment and sludge production take place under different technical, economic, and social contexts, thus requiring different approaches and involving different solutions. In most cases, a regular and environmentally safe wastewater treatment and associated sludge management requires the development of realistic and enforceable regulations, as well as treatment systems appropriate to local circumstances. The main objective of this paper is to provide useful information about the current wastewater and sludge treatment, management, regulations, and research in Oman. Based on the review and discussion, the wastewater treatment and sludge management in Oman has been evolving over the years. Further, the land application of sewage sludge should encourage revision of existing standards, regulations, and policies for the management and beneficial use of sewage sludge in Oman.
Implications: Wastewater treatment and sludge management in Oman have been evolving over the years. Sludge utilization has been a challenge due to its association with human waste. Therefore, composting of sewage sludge is the best option in agriculture activities. Sludge and wastewater utilization can add up positively in the economic aspects of the country in terms of creating jobs and improving annual income rate. The number of research projects done on wastewater reuse and other ongoing ones related to the land application of sewage sludge should encourage revision of existing standards, regulations, and policies for the management and beneficial use of sewage sludge in Oman. 相似文献
China's environmental problems and pollution control have global implications. China??s water pollution has been increasing with its urbanization and industrialization. Although great efforts have been taken to keep its wastewater discharge standards in pace with the water pollution development and technological advances, many challenges remain. A summary of the past achievements and lessons as well as the current problems in water pollution may provide a basis for future improvements in China and a reference for other countries.
Methods
Statistical data are summarized to reveal the evolution of China??s population, wastewater discharge and corresponding discharge standards over the past four decades. In particular, the specific control indexes and number of controlled items are discussed in details. The present water pollution situation is clearly illustrated by the water pollution map and the water quality distribution diagram. A comparison between China??s present wastewater discharge standards and those in the USA and the EU are also presented to find the possibilities for future improvement.
Results
The historical origins, major challenges and future perspectives of China??s wastewater discharge standards are overviewed. The barriers and ongoing efforts for standards formulation and implementation are highlighted. Some suggestions for future endeavors are given.
Conclusions
China??s wastewater discharge standard system has seen significant improvement over the past decades, but it still has many defects and limitations. Nonetheless, unprecedented great efforts are underway to address all these challenges. More stringent standards and subsequently a cleaner water environment in China can be expected in the near future. 相似文献
Use of sewage sludge, a biological residue produced from sewage treatment processes in agriculture, is an alternative disposal technique of waste. To study the usefulness of sewage sludge amendment for Helianthus annuus, a pot experiment was conducted by mixing sewage sludge at 2.5, 5, and 7.5 % (w/w) amendment ratios to the agricultural soil. Soil pH decreased whereas electrical conductivity, organic matter, total N, available P, and exchangeable Na, K, and Ca increased in soil amended with sewage sludge in comparison to unamended soil. Sewage sludge amendment led to significant increase in Pb, Ni, Cu, Cr, and Zn concentrations of soil. The increased concentration of heavy metals in soil due to sewage sludge amendment led to increases in shoot and root concentrations of Cr, Cu, Ni, and Zn in plant as compared to those grown on unamended soil. Accumulation was more in roots than shoots for most of the heavy metals. Moreover, high metal removal for the harvestable parts of the crops was recorded. Sewage sludge amendment increased root and shoot length, leaves number, biomass, and antioxidant activities of sunflower. Significant increases in the activities of antioxidant enzymes and in the glutathione, proline, and soluble sugar content in response to amendment with sewage sludge may be defense mechanisms induced in response to heavy metal stress.
Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and precursors and derivatives thereof have been employed as surfactants and anti-adhesives. PFOA and PFOS are environmentally persistent and the discharge of municipal waste waters is one of the principal routes of these compounds into the aquatic environment. In a previous study, the concentrations of PFOA and PFOS in grab samples collected from the waste water treatment plant (WWTP) of Bayreuth, a city of 72,000 inhabitants in Bavaria, Germany, during two periods showed considerable variability. For a better estimate of average mass flows, the surfactants were monitored (five samplings) from 16 March to 18 May 2007. In a second campaign, river water receiving the WWTP effluent was sampled twice a day for five consecutive days.
Methods
Quantitative analysis was done by stable-isotope dilution, pre-cleaning, and pre-concentration by solid-phase extraction, and liquid chromatography followed by electrospray ionization/tandem mass spectrometry.
Results
The mass flows of PFOA and PFOS through the WWTP were determined. PFOA is fully discharged into the river, while about half of PFOS is retained in the sewage sludge. The average daily mass load of the river Roter Main by the WWTP of Bayreuth is about 1.2?±?0.5 g PFOA and 5?±?2 g PFOS, with variations of up to 140% within one day.
Conclusion
Overall, the total annual release to the rivers of Germany may be in the range of several hundred kilograms of PFOA and several tons of PFOS. 相似文献
This study aimed to investigate the removal mechanisms of pharmaceutical active compounds (PhACs) and musks in a wastewater treatment plant (WWTP). Biological removal and adsorption in the activated sludge tank as well as the effect of UV radiation used for disinfection purposes were considered when performing a mass balance on the WWTP throughout a 2-week sampling campaign.
Methods
Solid-phase extraction (SPE) was carried out to analyse the PhACs in the influent and effluent samples. Ultrasonic solvent extraction was used before SPE for PhACs analysis in sludge samples. PhAC extracts were analysed by LC-MS. Solid-phase microextraction of liquid and sludge samples was used for the analysis of musks, which were detected by GC-MS. The fluxes of the most abundant compounds (13 PhACs and 5 musks) out of 79 compounds studied were used to perform the mass balance on the WWTP.
Results
Results show that incomplete removal of diclofenac, the compound that was found in the highest abundance, was observed via biodegradation and adsorption, and that UV photolysis was the main removal mechanism for this compound. The effect of adsorption to the secondary sludge was often negligible for the PhACs, with the exceptions of diclofenac, etofenamate, hydroxyzine and indapamide. However, the musks showed a high level of adsorption to the sludge. UV radiation had an important role in reducing the concentration of some of the target compounds (e.g. diclofenac, ibuprofen, clorazepate, indapamide, enalapril and atenolol) not removed in the activated sludge tank.
Conclusions
The main removal mechanism of PhACs and musks studied in the WWTP was most often biological (45%), followed by adsorption (33%) and by UV radiation (22%). In the majority of the cases, the WWTP achieved >75% removal of the most detected PhACs and musks, with the exception of diclofenac. 相似文献
With the aim of enhanced degradation of azo dye alizarin yellow R (AY) and further removal of the low-strength recalcitrant matter (LsRM) of the secondary effluent as much as possible, our research focused on the combination of aerobic bio-contact oxidation (ABO) with iron/carbon microelectrolysis (ICME) process.
Materials and methods
The combined ABO (with effective volume of 2.4?l) and ICME (with effectively volume of 0.4?l) process were studied with relatively short hydraulic retention time (HRT) of 4 or 6?h.
Results
At the HRT of 6?h with the reflux ratio of 1 and 2, the AY degradation efficiency in the final effluent was >96.5%, and the total organic carbon (TOC) removal efficiency were 69.86% and 79.44%, respectively. At the HRT of 4?h and the reflux ratio of 2, TOC removal efficiency and AY degradation efficiency were 73.94% and 94.89%, respectively. The ICME process obviously enhanced the total AY removal and the generated micromolecule acids and aldehydes then that wastewater backflow to the ABO where they were further biodegraded.
Conclusion
The present research might provide the potential options for the advanced treatment azo dyes wastewater with short HRT and acceptable running costs. 相似文献
The presence of four phenolic endocrine disrupting compounds (EDCs: nonylphenol [NP], NP monoethoxylate[NP1EO], bisphenol A [BPA], triclosan, [TCS]) and four nonsteroidal anti-inflammatory drugs (NSAIDs: ibuprofen[IBF], ketoprofen [KFN], naproxen [NPX], diclofenac [DCF]) in a Greek river receiving treated municipal wastewater was investigated in this study.
Methods
Samples were taken from four different points of the river and from the outlet of a sewage treatment plant (STP) during six sampling campaigns, and they were analyzed using gas chromatography?Cmass spectrometry.
Results
According to the results, EDCs were detected in almost all samples, whereas NSAIDs were detected mainly in wastewater and in the part of the river that receives wastewater from the STP. Among the target compounds, the highest mean concentrations in the river were detected for NP (1,345?ng?L?1) and DCF (432?ng?L?1). Calculation of daily loads of the target compounds showed that STP seems to be the major source of NSAIDs to the river, whereas other sources contribute significantly to the occurrence of EDCs. The environmental risk due to the presence of target compounds in river water was estimated, calculating risk quotients for different aquatic organisms (algae, daphnids, and fish). Results denoted the possible threat for the aquatic environment due to the presence of NP and TCS in the river. 相似文献
Polyvinyl alcohol (PVA) has been widely used as sizing agents in textile and manufacturing industry, and it is a refractory compound with low biodegradability.
Objective
The objective of this paper was to treat the PVA-containing wastewater using gamma irradiation as a pretreatment strategy to improve its biodegradability and to determine the roles of different kinds of radical species played during pretreatment.
Methods
Gamma radiation was carried out in a 60Cobalt source station, PVA concentration was analyzed by using a visible spectrophotometer and specific oxygen uptake rate (SOUR, milligram of O2 per gram of mixed liquor volatile suspended solids (MLVSS) per hour) was measured by a microrespirometer.
Results
The results showed that the biodegradability of PVA-containing wastewater with low initial concentration (e.g., 327.8?mg/l) could be improved greatly with increasing irradiation dose. However, PVA gel formation was observed at higher initial PVA concentration (e.g., 3,341.6?mg/l) and higher irradiation dose, which inhibited PVA degradation by aerobic microorganisms. However, the formed gel could be separated by microfiltration, which led to more than 90% total organic carbon (TOC) removal.
Conclusion
Ionizing radiation could be used as a pretreatment technology for PVA-containing wastewater, and its combination with biological process is feasible. 相似文献
Primitive wax refining techniques had resulted in almost 50,000 tonnes of acidic oily sludge (pH 1–3) being accumulated inside the Digboi refinery premises in Assam state, northeast India. A novel yeast species Candida digboiensis TERI ASN6 was obtained that could degrade the acidic petroleum hydrocarbons at pH 3 under laboratory conditions. The aim of this study was to evaluate the degradation potential of this strain under laboratory and field conditions.
Materials and methods
The ability of TERI ASN6 to degrade the hydrocarbons found in the acidic oily sludge was established by gravimetry and gas chromatography–mass spectroscopy. Following this, a feasibility study was done, on site, to study various treatments for the remediation of the acidic sludge. Among the treatments, the application of C. digboiensis TERI ASN6 with nutrients showed the highest degradation of the acidic oily sludge. This treatment was then selected for the full-scale bioremediation study conducted on site, inside the refinery premises.
Results
The novel yeast strain TERI ASN6 could degrade 40 mg of eicosane in 50 ml of minimal salts medium in 10 days and 72% of heneicosane in 192 h at pH 3. The degradation of alkanes yielded monocarboxylic acid intermediates while the polycyclic aromatic hydrocarbon pyrene found in the acidic oily sludge yielded the oxygenated intermediate pyrenol. In the feasibility study, the application of TERI ASN6 with nutrients showed a reduction of solvent extractable total petroleum hydrocarbon (TPH) from 160 to 28.81 g kg?1 soil as compared to a TPH reduction from 183.85 to 151.10 g kg?1 soil in the untreated control in 135 days. The full-scale bioremediation study in a 3,280-m2 area in the refinery showed a reduction of TPH from 184.06 to 7.96 g kg?1 soil in 175 days.
Discussion
Degradation of petroleum hydrocarbons by microbes is a well-known phenomenon, but most microbes are unable to withstand the low pH conditions found in Digboi refinery. The strain C. digboiensis could efficiently degrade the acidic oily sludge on site because of its robust nature, probably acquired by prolonged exposure to the contaminants.
Conclusions
This study establishes the potential of novel yeast strain to bioremediate hydrocarbons at low pH under field conditions.
Recommendations and perspectives
Acidic oily sludge is a potential environmental hazard. The components of the oily sludge are toxic and carcinogenic, and the acidity of the sludge further increases this problem. These results establish that the novel yeast strain C. digboiensis was able to degrade hydrocarbons at low pH and can therefore be used for bioremediating soils that have been contaminated by acidic hydrocarbon wastes generated by other methods as well. 相似文献
We analyzed and compared the distributions of 13 target pharmaceuticals in different water samples from the Hangzhou metropolitan area and Linan County, Southeast China.
Methods
Sampling was conducted in five hospitals, two wastewater treatment plants (WWTPs), and Qiantang River. Samples were concentrated by solid-phase extraction and PPCP concentrations were determined by UPLC-MS/MS.
Results and discussion
Trimethoprim, erythromycin A dihydrate, norfloxacin, ofloxacin, diclofenac sodium, and atenolol were the most frequently detected pharmaceuticals in hospital effluents. Most of the pharmaceutical concentrations in hospital effluents were higher than those in the WWTP influents. Although both WWTPs adopt the anaerobic?Caerobic?Canoxic treatment process, the removal rates for pharmaceuticals, such as trimethoprim and diclofenac sodium, were completely different. Meanwhile, erythromycin A dihydrate, ofloxacin, penicillin-G, cephalexin, cefazolin, ibuprofen, and diclofenac sodium were detected in Qiantang River.
Conclusions
These results indicate that hospitals are more concentrated sources of pharmaceuticals than WWTPs, and the WWTPs are not the only route of entry of pharmaceuticals into aquatic environments in these two regions. 相似文献
Incineration is a traditional method of treating sewage sludge and the disposal of derived ash is a problem of secondary waste treatment. In this study, sewage sludge ash (SSA) was coated with ferrite through a ferrite process and then used as an adsorbent for ionic dyes (methylene blue [MB] and Procion Red MX-5B [PR]). The modified SSA possessed surface potential that provided electrostatic attraction toward MB and PR. Adsorbent FA10 (named on the basis of being produced from 10 g of SSA in the ferrite process) was used for the adsorption of MB. Ideal pH for adsorption was 9.0 and maximum adsorption capacity based on Langmuir isotherm equation was 22.03 mg/g. Adsorbent FA2.5 (named on the basis of being produced from 2.5 g of SSA in the ferrite process) was used for PR adsorption. Ideal pH for adsorption was 3.0 and the maximum adsorption capacity (calculated as above) was 28.82 mg/g. Kinetic results reveal that both MB and PR adsorption fit the pseudo-second-order kinetic model better than the pseudo-first-order model. The values of activation energy calculated from rate constants were 61.71 and 9.07 kJ/mol for MB and PR, respectively.
Implications:
Magnetic modified adsorbent could be synthesized from sewage sludge ash (SSA). In this study, the adsorption ability of SSA toward ionic dye (methylene blue [MB] and Procion Red MX-5B [PR]) was enhanced by ferrite process. The synthesized Fe3O4 can act as an active site and provide electrostatic attraction toward cationic dye and anionic dye at different pH. The application of magnetic modified adsorbent in wastewater treatment can not only recycle the SSA, but also make SSA become an environmentally friendly material. 相似文献
The study examines the effectiveness of red mud, blast furnace (BF) slag, and alum-derived water treatment sludge as immobilizing agents for excessive soluble P that had accumulated in three green waste-based composts.
Methods
The three wastes were applied at 0%, 5%, 10%, and 20% w/w to three different composts, all containing extremely high concentrations of extractable P, and were incubated for 60?days. Water-soluble P was measured regularly throughout the incubation period, and at the end, P extractable with resin, 0.05?M NaHCO3, and 0.005?M H2SO4 were also measured.
Results
In the water extracts, inorganic P made up more than 85% of the total P present. All three materials had the ability to adsorb P and thus lowered water-soluble P concentrations. Water treatment sludge was clearly the most effective material, and this was attributed to its amorphous nature (thus, large Brunauer?CEmmett?CTeller surface area) and its acid pH (6.8) compared with the alkaline pH (10?C11) of the other two materials. Water treatment sludge was also the most effective at lowering resin- and NaHCO3-extractable P. When H2SO4 was used as the extractant, BF slag tended to be the most effective material at lowering extractable P, followed by water treatment sludge, and red mud. That is, the P immobilized by water treatment sludge was extractable with acid but not with water, resin, or NaHCO3.
Conclusions
Water treatment sludge has the potential to be used as an effective immobilizing agent for soluble P in composts, and it should be trialed under field conditions. 相似文献
Olive oil mill wastewater (OMW), a by-product of the olive oil extraction process, is annually produced in huge amounts in olive-growing areas and represents a significant environmental problem in Mediterranean areas. We studied the impact of OMW dilutions (1:20 and 1:10) on spinach plants in order to evaluate OMW dilutions as a low-cost alternative method for the disposal of this waste.
Materials and methods
The effects of OMW dilutions were evaluated on seed germination, shoot and root elongation, biomass production, nutrient uptake and translocation, ascorbic acid content, polyphenols, photosynthetic pigments, and photosynthetic performance of spinach.
Results
Plant biomass was more affected than plant height and total chlorophyll; carotenoid and ascorbic acid content progressively decreased with decreasing OMW dilution. Exposure to both OMW dilutions resulted in overaccumulation of total polyphenols, which were negatively correlated to plant biomass and nutrients. Nutrient (Fe, Ca, and Mg) content was insufficient leading to reduced growth. Water use efficiency decreased mainly due to decreased CO2 assimilation rate rather than to a decline of transpiration rate. Disturbances in photosystem II (PSII) photochemical efficiency could be better envisaged by the ratio between variable fluorescence and initial fluorescence (Fv/Fo), which showed much greater amplitude than the maximal photochemical efficiency of PSII photochemistry (Fv/Fm).
Conclusions
From the data obtained, it is suggested that 1:20 OMW dilutions are still phytotoxic and that higher OMW dilutions should be used in order to use this waste for the irrigation of spinach plants. 相似文献
From 2005, deposition of organic waste will be banned in Sweden. Likewise, in Germany and Austria, similar bans are being planned, and further countries will probably follow. Thus, there is a need to develop new methods and to refine established techniques for sludge management in the whole of the European Union. For this end, there is also an urgent need for appropriate ecotoxicological approaches to elucidate and assess the hazard potential of sewage sludge. Therefore, the present study was designed to assess the capacity of various established sludge treatment methods using different oxygen regimes to degrade recalcitrant nitro-substituted organic compounds and reduce their toxicity. Sewage sludge samples from a wastewater treatment plant in Sweden (Cambrex Karlskoga AB, industrial area Björkborn) receiving wastewater from industries manufacturing pharmaceutical substances, chemical intermediates and explosives were processed with different sludge treatment methods. Among other treatment methods, bioreactors (for anaerobic and aerobic sludge treatment) were used. In the present investigation, a battery ofin vitro bioassays was employed to compare the cytotoxic and genotoxic potentials of different fractions of sludge samples in order to elucidate whether the treatments were suitable to reduce the toxicity of the sludge.
Methods
In order to investigate the cytotoxicity of the extracts of treated and untreated sludge samples, the acute cytotoxicity test with the permanent cell line RTL-W1 was used. Genotoxicity was tested by means of the comet assay (single cell gel electro-phoresis) with RTL-W1cells, and mutagenicity was assessed with the Ames test using the Salmonella typhimurium strains TA98, TA98NR and TA100. Sludge toxicity was tested in different fractions of organic extracts produced by acetone and hexane extractions. The subsequent clean-up procedure (silica gel chro-matography and elution with hexane and dichloromethane) resulted in two fractions, a lipophilic hexane-fraction and a semi-lipophilic dichloromethane-fraction. For the genotoxicity and mutagenicity tests, these fractions were reunited at equal ratios.
Results and Discussion
The acute cytotoxicity test with RTL-Wl cells revealed a high cytotoxic potential for the semi-li-pophilic DM-fractions of all sludge samples with NR50 values (= effective concentration for 50% cell death in the neutral red test) from 8.9 up to 20 mg sludge d.w./ml medium. A low cytotoxic potential for the hexane fractions of the untreated sludge samples (NR50 400 to < 400 mg sludge d.w./ml medium) was observed, whereas the hexane fractions of the treated sludge samples showed elevated cytotoxicity increasing further with treatment in the bioreactors. The comet assay indicated that three out of eight of the reunited fractions had a significant genotoxic potential. Whereas the genotoxic potential of one sample treated anaerobically was very high with an induction factor of 11.6, a similar sample (taken from the same anaerobic reactor four months later) and one untreated sample showed lower potentials. The samples treated in another anaerobic bioreactor as well as the samples treated aerobically showed no genotoxic potential. Results indicate that aerobic treatment was basically adequate for reducing the genotoxicity of the sludge, whereas anaerobic treatment was only partly useful for reduction of genotoxicity. The Ames test revealed a very high mutagenic potential for the reunited fractions of the untreated sludge samples with strain TA98 (maximum induction factors (IFmax up to 45) and a relatively high potential for one of the samples treated aerobically (S2, IFmax = 18 (TA98, S9-)), thus documenting the suitability of both anaerobic and aerobic treatments to reduce the mutagenicity of the samples, however, with the aerobic treatment being less effective. Conclusions. Overall, none of the microbiological treatments for wastewater sludge in bioreactors was found to be ideal for general toxicity reduction of the sludge samples. Whereas cytotoxicity of the sludge increased or levelled off in most cases following either treatment, genotoxicity both increased or decreased after anaerobic treatment, depending on the specific sample. However, mutagenicity could generally be reduced by anaerobic treatment and, to a lesser degree, by aerobic treatment. Recommendationsand Perspectives. The complex modification of the diverse damage potentials of sludge sample extracts by use of anin vitro biotest battery following treatment for toxicity reduction in bioreactors showed that considerations of different toxicological endpoints is essential for an adequate hazard assessment. Whereas in the case of cytotoxicity reduction, the reactors proved ineffective, mutagenicity could be reduced significantly at least in some cases in this case study.
Ciprofloxacin (CIP), a broad-spectrum, second-generation fluoroquinolone, has frequently been found in hospital wastewaters and effluents of sewage treatment plants. CIP is scarcely biodegradable, has toxic effects on microorganisms and is photosensitive. The aim of this study was to assess the genotoxic potential of CIP in human HepG2 liver cells during photolysis.
Methods
Photolysis of CIP was performed in aqueous solution by irradiation with an Hg lamp, and transformation products were monitored by HPLC-MS/MS and by the determination of dissolved organic carbon (DOC). The cytotoxicity and genotoxicity of CIP and of the irradiated samples were determined after 24?h of exposure using the WST-1 assay and the in vitro micronucleus (MN) test in HepG2 cells.
Results
The concentration of CIP decreased during photolysis, whereas the content of DOC remained unchanged. CIP and its transformation products were not cytotoxic towards HepG2 cells. A concentration-dependent increase of MN frequencies was observed for the parent compound CIP (lowest observed effect level, 1.2???mol?L?1). Furthermore, CIP and the irradiated samples were found to be genotoxic with a significant increase relative to the parent compound after 32?min (P?P?Conclusions Photolytic decomposition of aqueous CIP leads to genotoxic transformation products. This proves that irradiated samples of CIP are able to exert heritable genotoxic effects on human liver cells in vitro. Therefore, photolysis as a technique for wastewater treatment needs to be evaluated in detail in further studies, not only for CIP but in general. 相似文献
The project was set to construct an extensive wetland in the southernmost region of Israel at Kibbutz Neot Smadar (30°02′45″ N and 35°01′19″ E). The results of the first period of monitoring, summary, and perspectives are presented. The constructed wetland (CW) was built and the subsequent monitoring performed in the framework of the Southern Arava Sustainable Waste Management Plan, funded by the EU LIFE Fund. The specific aims were: (1) To end current sewage disposal and pollution of the ground, the aquifer, and the dry river bed (wadi) paths by biologically treating the sewage as part of the creation of a sustainable wetland ecosystem. (2) Serve as an example of CW in the Negev highlands and the Arava Valley climates for neighboring communities and as a test ground for plants and building methods appropriate to hyper arid climate. (3) Serve as an educational resource and tourist attraction for groups to learn about water reuse, recycling, local wildlife and migrating birds, including serving the heart of a planned Ecological–Educational Bird Park. This report is intended to allow others who are planning similar systems in hyper arid climates to learn from our experience.
Materials and methods
The project is located in an extreme arid desert with less than 40 mm of rain annually and temperature ranges of ?5°C to +42°C. The site receives 165–185 m3 of municipal and agricultural wastes daily, including cowshed and goat wastes and winery outflow.
Results
The CW establishment at Neot Smadar was completed in October 2006. For 8 months, clean water flowed through the system while the plants were taking root. In June 2007, the wetland was connected to the oxidation pond and full operation began. Because of seepage and evaporation, during the first several months, the water level was not high enough to allow free flow from one bed to the next. To bed A, the water was pumped periodically from the oxidation pond (Fig. 1) and from there flowed by gravitation through the rest of the system. The initial results of the monitoring are promising. In nearly all measurements, the system succeeded as expected to reduce levels of contaminants at least to the level acceptable for irrigating fruit trees and often to the level of unlimited irrigation. The introduction of the plants in the system and their physiological performance were evaluated and were found to correlate well to the quality of water in the various beds.
Discussion
It should be said at the outset that evaluation of the performance of a CW system is a long-term process. Thus, the main aim of this report is to present the problems, difficulties, preliminary results, and concepts concerned with the first stage of establishment of CW in an extremely dry region.
Conclusions
The CW system was designed to dispose of municipal and agricultural wastes in a way that not merely reduces pollution, but adds to environmental quality by creating accessible parkland for local residents and tourists. Several factors affected the performance of the system at the initial stages of operation: ecological balance between microbes and plants, big seasonal variations, seepage and evaporation reduced the flow in the initial operation of the system. Despite the initial difficulties, the quality of water coming out the system is acceptable for irrigation.
Recommendations and perspectives
The CW can function well under extreme dryland conditions. The oxidation pond was the major source of evaporation and bad odors. Therefore, alternatives to the oxidation pond are needed. Cost effectiveness of the system still has to be evaluated systematically. 相似文献
Owing to the present complexity and difficulty of concentrated dye wastewater treatment, this work aimed to synthesize a reproducible waste-sorbing material for the treatment of wastewater by forming the dye-conjugating complex hybrid.
Methods
The inorganic/organic hybridization was applied to prepare the objective material by immobilizing waster dye-Mordant blue 9 (MB) with barium sulfate (BaSO4). The composition and pattern of the formed material were determined by spectrometry and characterized by SEM and XRD, and their formation process was clarified. The adsorption of cationic dye-basic blue BO (BB) and copper ion was investigated..
Results
The hybrid of MB alone into growing BaSO4 formed the pineapple-like particles while that of the MB/BB-conjugating complex was the rhombus material. The adsorption of BB on the MB–BaSO4 hybrid was probably attributed to ion-pair equilibrium and that of Cu2+ may result from the complexation. The treatment of dye and heavy metal wastewaters indicated that the MB hybrid material removed 99.8% BB and 97% Cu2+ and the dye-conjugating hybrid with growing BaSO4 100% MB, 99.5% BB, and 44% Cu2+.
Conclusion
The waste MB–BaSO4 hybrid material is efficient to treat cationic dye and Cu2+ wastewater. The dye-conjugating hybridization method is the first to be advanced for in situ wastewater treatment, and it showed a combined effect for the removal of both organic dyes and heavy metals. 相似文献
