Detection of toxic substances in water by means of a mammalian cell culture technique

The cloning efficiency of a mammalian cell culture was used as a sensitive technique for the detection of toxicants in water. The sensitivity of the technique was tested by exposing HeLa, mouse lymphoma and Buffalo green monkey cell lines to known amounts of six different toxicants. The cell culture system tested proved to be twice as sensitive as an electronic fish bioassay system. Biofilter humus tank, and activated sludge effluents as well as settled sewage showed toxic activity when tested by the cell culture system.     

The treatment and reuse of wastewater in the textile industry by means of ozonation and electroflocculation

Two different oxidation treatments, ozonation and electroflocculation, were experimented on a pilot scale to test their efficiency in removing polluting substances from wastewaters of textile industries. Both pilot plants used reproduced very closely a full-scale treatment in order to obtain indications about the feasibility of a transfer on industrial scale. By means of ozone treatment very high colour removal (95-99%) was achieved and treated waters were reused satisfactorily in dyeing even with light colours. This evidence despite the fact that the chemical oxygen demand of treated waters was still in a range (75-120 mg/l, a decrease up to 60%) that was usually considered to be too high for recycling purposes, especially for dyeing light colours. Treating plants working at the above-mentioned conditions should guarantee low operating costs. A biological pre-treatment and a sand filtration are absolutely essential. The transfer on industrial scale of the treatment is currently under development under an already financed European project. Electrochemical treatment showed to be very efficient in removing colour (80-100%) and chemical oxygen demand (70-90%). Moreover, a sensible decrease of chloride and sulphate ions was detected. Removal of flocculated material (post-treatment) must be, however, perfected in order to establish a correct costs-to-benefits ratio and therefore, propose an implementation of the technique on an industrial scale.     

Removal of native coliphages and coliform bacteria from municipal wastewater by various wastewater treatment processes: implications to water reuse

The efficacy of a conventional activated sludge wastewater treatment process and the membrane bioreactor technology in removing microbial pathogens was investigated. Total and fecal coliforms and somatic and F-specific coliphages were used as indicators of pathogenic bacteria and viruses. Up to 5.7 logs removal of coliforms and 5.5 logs of coliphages were observed in the conventional treatment process with advanced tertiary treatment. Addition of chemical coagulants seemed to improve the efficacy of primary and secondary treatment for microorganism removal. Complete removal of fecal coliforms and up to 5.8 logs removal of coliphages was observed in the MBR system. It was shown that the MBR system was capable of high removal of coliphages despite the variation in feed coliphage concentrations. The results of this study indicated that the MBR system can achieve better microbial removal in far fewer steps than the conventional activated sludge process with advanced tertiary treatment. The final effluent from either treatment processes can be potentially reused.     

UV inactivation and resistance of rotavirus evaluated by integrated cell culture and real-time RT-PCR assay

Rotaviruses are double-stranded RNA viruses which are among the most resistant waterborne enteric viruses to UV disinfection. An integrated cell culture and real-time RT-PCR (ICC real-time RT-PCR) assay was developed to detect the infectivity of rotaviruses in water, which uses real-time RT-PCR to detect RNA produced by infectious rotaviruses during replication in host cells. Detection of rotaviral RNA in host cells provides direct evidence of the presence of infectious rotavirus rather than just the presence of rotavirus RNA. Using this newly developed method, the inactivation and resistance of rotavirus to UV treatments at various doses was evaluated. With an initial concentration of 2 × 10⁴ PFU/ml simian rotavirus (SA11), a first-order linear relationship was obtained at UV dose range of 0-120 mJ cm⁻², and the inactivation rate constant was estimated to be 0.0343 cm² mJ⁻¹ (R² = 0.966). The dose-inactivation curve tailed off and reached plateau as the UV dose increased from 120 to 360 mJ cm⁻², indicating resistance phenomena of sub-populations of SA11 at very high UV doses. A maximal reduction of 4.8 log₁₀ was observed. Through parallel comparison with traditional culture assay, the ICC real-time RT-PCR method demonstrated more effective, sensitive and faster infectivity detection of rotavirus and, the results reveal that rotaviruses are more resistant to UV irradiation than previously reported with traditional cell culture assays.     

Electrochemical disinfection of biologically treated wastewater from small treatment systems by using boron-doped diamond (BDD) electrodes – Contribution for direct reuse of domestic wastewater

The aim of the study was to demonstrate the application potential of boron-doped diamond electrodes (BDD) in electrochemical disinfection of biologically treated sewage for direct recycling of domestic wastewater. Discontinuous bulk disinfection experiments with secondary effluents and model solutions were performed to investigate the influence of operating conditions and wastewater parameters on disinfection efficiency and formation of disinfection by-products (adsorbable organically bound halogens, AOX). The inactivation rate accelerates with increasing current density caused by a faster generation of electrochemical oxidants (ECO). It could be shown that the effect of OH radicals in case of the direct electrochemical disinfection of chloride-containing secondary effluents with BDD is negligible because of their fast reaction with typical radical scavengers. The dominating role of electrochemically generated free chlorine in the disinfection process could be explicitly verified. It could be also shown that the disinfection efficiency is strongly affected by the specific wastewater parameters temperature and pH. These effects can be explained by the behaviour of the reactive species. The migration-controlled generation of ECO can be accelerated under turbulent hydrodynamic conditions. The formation of disinfection by-products (AOX) correlates with the introduced electric charge Q applied per volume and is independent of the applied current density.     

Effects of sonication on bacteria viability in wastewater treatment plants evaluated by flow cytometry--fecal indicators, wastewater and activated sludge

The application of sonication to wastewater or sludge contributes to the dispersion of aggregates, the solubilisation of particulate matter with an increase in its biodegradability, the damage of microorganisms due to the loss of cellular membrane integrity. This research is aimed at investigating the effects of sonication at 20kHz frequency on viability of microorganisms present in raw wastewater and activated sludge taken from a municipal wastewater treatment plant, as well as pure strains of Escherichia coli and E. faecalis. Flow cytometry was applied for the identification and quantification of viable and dead bacteria free in the bulk liquid, after the fluorescent staining of cellular nucleic acids. The main results showed that: (i) cells of E. coli were highly sensitive to sonication, even at low specific ultrasonic energy (E(s)), and disintegration of a large amount of cells was observed; (ii) on the contrary E. faecalis were more resistant than E. coli, even if high levels of E(s) were applied; (iii) bacteria in raw wastewater exhibited a dynamic of viable and dead bacteria similar to E. coli; (iv) in activated sludge samples, low levels of E(s) produced a prevalent disaggregation of flocs releasing single cells in the bulk liquid, while disruption of bacteria was induced only by very high levels of E(s).     

Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles

Hexavalent chromium existing in the effluent is a major concern for the metal-processing plant. In this study, a new method combining nanoparticle adsorption and magnetic separation was developed for the removal and recovery of Cr(VI) from wastewater. The nanoscale maghemite was synthesized, characterized, and evaluated as adsorbents of Cr(VI). Various factors influencing the adsorption of Cr(VI), e.g., pH, temperature, initial concentration, and coexisting common ions were studied. Adsorption reached equilibrium within 15 min and was independent of initial Cr concentration. The maximum adsorption occurred at pH 2.5. The adsorption data were analyzed and fitted well by Freundlich isotherm. Cr(VI) adsorption capacity of maghemite nanoparticles was compared favorably with other adsorbents like activated carbon and clay. Competition from common coexisting ions such as Na+, Ca2+, Mg2+, Cu2+, Ni2+, NO3-, and Cl- was ignorable, which illustrated the selective adsorption of Cr(VI) from wastewater. Regeneration studies verified that the maghemite nanoparticles, which underwent six successive adsorption-desorption processes, still retained the original metal removal capacity. In addition, the adsorption mechanisms were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic techniques.     

生物接触氧化与二氧化氯工艺处理医疗废水

结合工程实例,介绍了水解酸化、生物接触氧化与二氧化氯消毒工艺在处理医疗废水工程中的应用,工程运行表明,该工艺可行,运行稳定,出水水质各项指标均达到GB 8978-1996污水综合排放标准中的一级标准。     

Removal of trace metals from wastewater by treatment with lime and discarded automotive tires

Discarded automotive tires, a solid waste disposal problem of enormous proportions, may provide the answer to another environmental headache—the removal of trace metals from wastewaters.Experiments were designed to evaluate the feasibility of using discarded automotive tires in conjunction with time to remove aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, silver and zinc from aqueous solutions.Continuous bench-scale studies showed that removals in excess of 99.5 per cent for most of the metals can be achieved by treatment with lime and discarded automobile tires.     

Removal mechanisms for endocrine disrupting compounds (EDCs) in wastewater treatment - physical means, biodegradation, and chemical advanced oxidation: a review

Endocrine disrupting compounds (EDCs) are pollutants with estrogenic or androgenic activity at very low concentrations and are emerging as a major concern for water quality. Within the past few decades, more and more target chemicals were monitored as the source of estrogenic or androgenic activity in wastewater, and great endeavors have been done on the removal of EDCs in wastewater. This article reviewed removal of EDCs from three aspects, that is, physical means, biodegradation, and chemical advanced oxidation (CAO).     

Removal of phosphate,magnesium and calcium from swine wastewater through crystallization enhanced by aeration

In order to confirm the possibility of removing P04-P, Mg and Ca from swine wastewater through artificial crystallization by aeration, laboratory and pilot scale experiments were carried out using actual swine wastewater. The pH of swine wastewater increased up to approximately 8.5 with continuous aeration, and a large part of the soluble PO4-P, Mg and Ca was crystallized. The ingredients of the crystals were estimated as MAP and HAP according to their mole ratio of NH4-N, PO4-P, Mg and Ca. The sedimentation speed of crystals in swine wastewater was about 3 m h(-1), and over 90% of them had settled after standing 1 h. A pilot scale reactor with the dual functions of crystallization by aeration and settling was operated continuously using actual swine wastewater, with aeration conditions of HRT 4.1 h and 26m3 airh(-1) m(-2) cross section (18m3 air h(-1) m(-3) volume). During 50 days of operation, pH at the aeration column held stable at 8.0, and 65% of PO4-P, 51% of Mg, and 34% of Ca were removed.     

Routine monitoring of antibiotics in water and wastewater with a radioimmunoassay technique

Antibiotics are one of a group of pharmaceutical compounds that have been found in lakes and streams throughout the world and the occurrence of these compounds in the environment has raised concerns regarding the toxicity to aquatic organisms and the emergence of strains of antibiotic-resistant bacteria. The objective of this study was to assess the use of a relatively simple coupled solid-phase extraction (SPE)/radioimmunoassay (RIA) method for screening and/or monitoring tetracycline (TC) and sulfonamide (SA) compounds in water. Cross-reactivity of TCs and SAs was used to determine the specificity of the assays. The results indicate that TC, oxytetracycline (OTC), chlortetracycline (CTC) of the investigated 5 TCs, and sulfamethazine (SMT), sulfamethoxazole (SMX), sulfadimethoxane (SDM) and sulfathiazole (STZ) of the investigated 6 SAs in water matrix cross-react to a similar degree within each family in RIA and SPE/RIA. Water samples were collected across a watershed in northern Colorado in addition to the influent and effluent of a wastewater treatment plant. SPE/RIA analysis of these samples was compared with SPE/liquid chromatography (LC)-mass spectrometry (MS) quantification of 5 TC and 6 SA compounds. Results of the study indicate that SPE/RIA can be an effective technique for monitoring antibiotic compounds in waters suspected to be contaminated with these compounds. The coupled method provides a sufficiently low detection limit (0.05 microg/L) to screen large sample sets at environmentally relevant concentrations. The method provides a semi-quantitative composite measurement of similar compounds in an antibiotic family without complex and expensive analytical equipment.     

Detection of potential carcinogens and toxicants in tap and reclaimed water by the golden hamster cell transformation assay

A transformation assay using primary golden hamster embryonic cells was used for detection of potential carcinogens in water. The system also gave an indication of toxicants present in water and proved to be highly sensitive, because no concentration or extraction procedures were required as in the case of the Ames Salmonella/microsome assay.

Direct reclamation of secondary treated wastewater proved to be highly effective when tested by the golden hamster transformation assay. Reclaimed water showed less transforming activity than a high quality tap water derived from conventional treatment of surface water.     

Detection of adenoviruses in shellfish by means of conventional-PCR, nested-PCR, and integrated cell culture PCR (ICC/PCR)

We tested three PCR based methodologies to detect adenoviruses associated with cultivated oysters. Conventional-PCR, nested-PCR, and integrated cell culture-PCR (ICC/PCR) were first optimized using oysters seeded with know amounts of Adenovirus serotype 5 (Ad5). The maximum sensitivity for Ad5 detection was determined for each method, and then used to detect natural adenovirus contamination in oysters from three aquiculture farms in Florianopolis, Santa Catarina State, Brazil, over a period of 6 months. The results showed that the nested-PCR was more sensitive (limit of detection: 1.2 PFU/g of tissue) than conventional-PCR and ICC-PCR (limit of detection for both: 1.2 x 10(2)PFU/g of tissue) for detection of Ad5 in oyster extracts. Nested-PCR was able to detect 90% of Ad5 contamination in harvested oyster samples, while conventional-PCR was unable to detect Ad5 in any of the samples. The present work suggests that detection of human adenoviruses can be used as a tool to monitor the presence of human viruses in marine environments where shellfish grow, and that nested-PCR is the method of choice.     

Removal of DDD and DDE from wastewater using bagasse fly ash, a sugar industry waste

Bagasse fly ash, a waste from the sugar industry, was converted into an effective adsorbent and was used for the removal of DDD [2,2-Bis(4-chlorophenyl)-1,1-dichloroethane] and DDE [2,2-Bis(4-chlorophenyl)-1,1-dichloroethene] pesticides from wastewater. The DDD and DDE are removed by the developed adsorbent up to 93% at pH 7.0, with the adsorbent dose of 5 g/l of particle size 200-250 microns at 30 degrees C. The removal of these two pesticides was achieved up to 97-98% in column experiments at a flow rate of 0.5 ml/min. The adsorption was found to be exothermic in nature. The bagasse fly ash system has been used for the removal of DDD and DDE from the wastewater. The developed system is very useful, economic, and reproducible.     

Removal of carbon and nutrients from domestic wastewater using a low investment, integrated treatment concept

An integrated chemical-physical-biological treatment concept for the low-cost treatment of domestic wastewater is proposed. Domestic wastewater was subjected to a chemically enhanced primary treatment (CEPT), followed by treatment in an upflow anaerobic sludge blanket (UASB) reactor. In addition, a regenerable zeolite was used to remove NH4+, either after CEPT pretreatment or after biological treatment in the UASB reactor. The CEPT pretreatment consisted of the addition of a coagulant (FeCl3) and an anionic organic flocculant and removed on average 73% of the total chemical oxygen demand (COD(t)), 85% of the total suspended solids, and 80% of PO4(3-) present in the wastewater. The UASB system, which consequently received a low COD(t) input of approximately 140 mg/L, was operated using a volumetric loading rate of 0.4 g COD(t)/L. d (hydraulic retention time [HRT]=10 h) and 0.7 g COD(t)/L. d (HRT=5 h). For these conditions, the system removed about 55% of the COD(t) in its influent, thus producing an effluent with a low COD(t) of approximately 50 mg/L. The zeolite, when applied in batch mode before the UASB reactor, removed approximately 45% of the NH4+, whereas its application as a post-treatment cartridge resulted in almost 100% NH4+ removal. The simple design and relatively low operating costs, due to low costs of added chemicals and low energy input (estimated at Euro 0.07-0.1 per m3 wastewater treated), combined with excellent treatment performance, means that this system can be used as a novel domestic wastewater treatment system for developing countries. Therefore, the system is called a Low Investment Sewage Treatment (LIST) system.     

Assessment of soil and groundwater impacts by treated urban wastewater reuse. A case study: application in a golf course (Girona, Spain)

Starting in July 2000, treated wastewater of urban origin has been used for the "Serres de Pals" golf course irrigation (Girona, Spain). To evaluate if the soil and the aquifer underneath are affected by the utilization of this type of water, samples have been taken along a period of several months from the wastewater treatment plant, the stabilization lagoon, groundwater and soil profiles. Analyses have been performed for total coliforms and aerobic bacteria, soil water pressure and soil water content as well as chemical analyses of the irrigation water, aquifer and water of the vadose zone. Soil profiles taken at several times during the study indicate the absence of coliforms except for a short period during summer. In the vadose zone an increase of more than 1000 mg kg(-1) of NaO(2) in the top 60 cm of soil was observed while Cl(-) concentration in the aquifer reached up to 1200 mg l(-1) ten months after starting the irrigation.     

Denitrification and neutralization treatment by direct feeding of an acidic wastewater containing copper ion and high-strength nitrate to a bio-electrochemical reactor process.

The feasibility of the direct denitrification treatment of copper metal pickling wastewater by using a bio-electrochemical reactor process was investigated experimentally. Carbon electrodes were installed in the reactor as the anode and cathode and denitrifying microorganisms were fixed on the surface of the cathode. The reactor was continuously operated by applying an electric current and feeding acetate. In this reactor, copper ion removal and denitrification proceeded simultaneously and the pH value of the treated water was increased almost to neutral. The electric current that passed through the cathode contributed to the removal of the copper ion and the generation of hydrogen gas. The generated hydrogen gas as well as the added acetate was effectively utilized for denitrification. A theoretical evaluation of pH in the effluent suggested that the pH increase was mainly caused by the generation of hydroxyl ion during denitrification. In addition, the inorganic carbon species generated during denitrification with acetate and by the electrochemical oxidation of anodic carbon acted as a buffer to minimize a further increase of pH at higher nitrate removal efficiencies. These results demonstrated that copper ion removal, denitrification and neutralization could be achieved simultaneously by using a single bioelectrochemical reactor.