The present study addresses the key issue of linking the chemical speciation to the uptake of priority pollutants Cd(II) and Pb(II) in the wastewater treatment plant effluents, with emphasis on the role of the colloidal organic matter (EfOM). Binding of Cd(II) and Pb(II) by EfOM was examined by an ion exchange technique and flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry in parallel to bioassays with green microalga Chlorella kesslerii in ultrafiltrate (<1 kDa) and colloidal isolates (1 kDa to 0.45 μm). The uptake of Cd by C. kesslerii was consistent with the speciation analysis and measured free metal ion concentrations, while Pb uptake was much greater than that expected from the speciation measurement. Better understanding of the differences in the effects of the EfOM on Cd(II) and Pb(II) uptake required to take into account the size dependence of metal binding by EfOM. Colloids isolated from WWTP effluents decrease Cd uptake, but increase Pb uptake by microalga Chlorella kesslerii.

An eco-restoration system to remove excess nutrients and restore the agricultural ecosystem balance was proposed and applied from August 2006 to August 2008 in a residential-cropland complex area (1.4 × 105 m2) in Kunming, western China, where the self-purifying capacity of the agricultural ecosystem had been lost. The proposed eco-restoration system examined includes three main foci: farming management, bioremediation, and wastewater treatment. The results showed that the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) from the complex wastewater were 83% and 88%, respectively. The Simpson’s diversity indices of macrophytes and zoobenthos indicated that the system had increased macrophyte and zoobenthic diversity as well as improved growth conditions of the plankton habitats. The results demonstrated that the proposed eco-restoration system is a promising approach for decreasing the output of nutrients from soil, improving agricultural ecosystem health, and minimizing the downstream eutrophication risk for surface waters.

Background, aim and scope Pulp and paper mills generate a plethora of pollutants depending upon the type of pulping process. Efforts to mitigate the environmental impact of such effluents have been made by developing more effective biological treatment systems in terms of biochemical oxygen demand, chemical oxygen demand, colour and lignin content. This study is the first that reports an evaluation of the effects of a tertiary treatment by fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium and Rhizopus oryzae) on individual organic compounds of a Eucalyptus globulus bleached kraft pulp and paper mill final effluent after secondary treatment (final effluent). Material and methods The tertiary treatment with P. sajor caju, T. versicolor and P. chrysosporium and R. oryzae was performed in batch reactors, which were inoculated with separate fungi species and monitored throughout the incubation period. Samples from effluent after secondary and after tertiary treatment with fungi were analysed for both absorbance and organic compounds. The samples were extracted for organic compounds using solid-phase extraction (SPE) and analysed by gas chromatography-mass spectrometry (GC/MS). The efficiencies of the SPE procedure was evaluated by recovery tests. Results A total of 38 compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were identified and quantified in the E. globulus bleached kraft pulp mill final effluent after secondary treatment. Recoveries from the extraction procedure were between 98.2% and 99.9%. The four fungi species showed an adequate capacity to remove organic compounds and colour. Tertiary treatment with R. oryzae was able to remove 99% of organic compounds and to reduce absorbance on 47% (270 nm) and 74% (465 nm). P. sajor caju, T. versicolor and P. chrysosporium were able to remove 97%, 92% and 99% of organic compounds, respectively, and reduce 18% (270 nm) to 77% (465 nm), 39% (270 nm) to 58% (465 nm) and 31% (270 nm) to 10% (465 nm) of absorbance, respectively. Discussion The wide variety of organic compounds found in the final effluent must be due to the degradation of E. globulus wood in pulp and paper mill. The concentrations of organic compounds in the final effluent of E. globulus bleached kraft pulp mill were in residual levels maybe due to the secondary treatment. The recovery tests showed the effectiveness of the extraction procedure, and no losses of analyte were suspected in the analytical determinations. Lignin derivatives such as vanilic acid, syringic acid, guaiacol, syringol and phloroglucinol were totally removed by R. oryzae, but the 47% absorbance reduction obtained at 270 nm suggests that these species were not able to complete degradation of lignin macromolecular compounds. Conclusions The organic compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were removed more efficiently by tertiary treatment with R. oryzae or P. chrysosporium, followed by P. sajor caju and T. versicolor. Regarding the removal of both colour and organic compounds, the tertiary treatment with R. oryzae was the most efficient. Recommendations and perspectives In order to reduce the deleterious impacts of paper mill effluents, efforts have been made to develop more effective advanced tertiary treatments. This study may serve as a basis of characterisation, in terms of organic compounds of E. globulus bleached kraft pulp mill final effluent after secondary treatment and as an effort to understand the effects of tertiary treatments with fungi on low concentrations of organic compounds from biological secondary treatment.

Background, aim, and scope Organoarsenical-containing animal feeds that promote growth and resistance to parasites are mostly excreted unchanged, ending up in nearby wastewater storage lagoons. Earlier work documented the partial transformation of organoarsenicals, such as, 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) to the more toxic inorganic arsenate [As(V)] and 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA). Unidentified roxarsone metabolites using liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC/ICP-MS) were also inferred from the corresponding As mass balance. Earlier batch experiments in our laboratory suggested the presence of organometallic (Cu) complexes during relevant roxarsone degradation experiments. We hypothesized that organocopper compounds were complexed to roxarsone, mediating its degradation in field-collected swine wastewater samples from storage lagoons. The objective of this study was to investigate the role of organometallic (Cu) complexes during roxarsone degradation under aerobic conditions in swine wastewater suspensions, using electrospray ionization mass spectrometry (ES-MS). Materials and methods Two swine wastewater samples differing in % solids content and total recoverable Cu concentrations were reacted with 500 ppb of roxarsone under aerobic conditions for 16 days. LC/ICP-MS and ES-MS were used for As speciation analyses, and characterization of metal-organoarsenical complexes in swine wastewater subsamples, respectively. Results and discussion An organocopper roxarsone metabolite was found only in the high-Cu wastewater sample, suggesting the role of Cu in roxarsone degradation under aerobic conditions. The organocopper metabolite was not found in the low-Cu wastewater sample, because roxarsone did not undergo degradation under aerobic conditions even after 16 days. Conclusions Aerobic degradation of organoarsenicals (roxarsone) has not been documented before. Preliminary dataset from this study illustrates the direct and/or indirect association of particulate Cu in catalyzing roxarsone degradation under aerobic conditions in samples with high % solids content. Recommendations and perspectives Concerns regarding the degradation of roxarsone in wastewater to the more toxic inorganic As may be partially linked to the presence of particulate Cu. The presence of Cu in wastewater-suspended particle surfaces has never been coupled before to organoarsenicals degradation reactions, thus, further studies are needed to elucidate the related reaction mechanisms and pathways. Water depth-dependent solid particle distribution profiles in wastewater storage lagoons could provide empirical evidence towards the design of effective degradation practices for nitrophenol-containing compounds, such as, organoarsenical-containing antibiotics, or explosive munitions compounds.

Background, aim and scope Toxicity testing has become a suitable tool for wastewater evaluation included in several reference documents on best available techniques of the Integrated Pollution Prevention and Control (IPPC) Directive. The IPPC Directive requires that for direct dischargers as well as for indirect dischargers, the same best available techniques should be applied. Within the study, the whole effluent assessment approach of OSPAR has been applied for determining persistent toxicity of indirectly discharged wastewater from the metal surface treatment industry. Materials and methods Twenty wastewater samples from the printed circuit board and electroplating industries which indirectly discharged their wastewater to municipal wastewater treatment plants (WWTP) have been considered in the study. In all factories, the wastewater partial flows were separated in collecting tanks and physicochemically treated in-house. For assessing the behaviour of the wastewater samples in WWTPs, all samples were biologically pretreated for 7 days in the Zahn-Wellens test before ecotoxicity testing. Thus, persistent toxicity could be discriminated from non-persistent toxicity caused, e.g. by ammonium or readily biodegradable compounds. The fish egg test with Danio rerio, the Daphnia magna acute toxicity test, the algae test with Desmodesmus subspicatus, the Vibrio fischeri assay and the plant growth test with Lemna minor have been applied. All tests have been carried out according to well-established DIN or ISO standards and the lowest ineffective dilution (LID) concept. Additionally, genotoxicity was tested in the umu assay. The potential bioaccumulating substances (PBS) were determined by solid-phase micro-extraction and referred to the reference compound 2,3-dimethylnaphthalene. Results The chemical oxygen demand (COD) and total organic carbon (TOC) values of the effluents were in the range of 30-2,850 mg L⁻¹ (COD) and 2-614 mg L⁻¹ (TOC). With respect to the metal concentrations, all samples were not heavily polluted. The maximum conductivity of the samples was 43,700 µS cm⁻¹ and indicates that salts might contribute to the overall toxicity. Half of the wastewater samples proved to be biologically well treatable in the Zahn-Wellens test with COD elimination above 80%, whilst the others were insufficiently biodegraded (COD elimination 28-74%). After the pretreatment in the Zahn-Wellens test, wastewater samples from four (out of ten) companies were extremely ecotoxic especially to algae (maximum LIDA = 16,384). Three wastewater samples were genotoxic in the umu test. Applying the rules for salt correction of test results as allowed in the German Wastewater Ordinance, only a small part of toxicity could be attributed to salts. Considering the PBS, wastewater from the metal surface treatment industry exhibited very low levels of PBS. In one factory, the origin of ecotoxicity has been attributed to the organosulphide dimethyldithiocarbamate (DMDTC) used as a water treatment chemical for metal precipitation. The assumption based on rough calculation of input of the organosulphide into the wastewater was confirmed in practice by testing its ecotoxicity at the corresponding dilution ratio after pretreatment in the Zahn-Wellens test. Whilst the COD elimination of DMDTC was only 32% in 7 days, the pretreated sample exhibited a high ecotoxicity to algae (LIDA = 1,536) and luminescent bacteria (LIDlb = 256). Discussion Comparative data from wastewater surveillance by authorities (data from 1993 to 2007) confirmed the range of ecotoxicity observed in the study. Whilst wastewater from the metal surface treatment industry usually did not exhibit ecotoxicity (median LID 1-2), the maximum LID values reported for the algae, daphnia and luminescent bacteria tests were very high (LIDA up to 3,072, LIDD up to 512 and LIDlb up to 2,048). DMDTC was found to be one important source of ecotoxicity in galvanic wastewater. DMDTC is added in surplus, and according to the supplier, the amount in excess should be detoxified with ferric chloride or iron sulphate. The operator of one electroplating company had not envisaged a separate treatment of the organosulphide wastewater but was assuming that excess organosulphide would be bound by other heavy metals in the sewer. DMDTC degrades via hydrolysis to carbon disulfide (which is also toxic to animals and aquatic organisms), carbonyl sulphide, hydrogen sulphide and dimethylamine, but forms complexes with metals which stabilise the compound with respect to transformation. Although no impact on the WWTP is expected, the question arises whether the organosulphide is completely degraded during the passage of the WWTP. Conclusions and recommendations The results show that the organic load of wastewater from the electroplating industry has been underestimated by focussing on inorganic parameters such heavy metals, sulphide, cyanide, etc. Bioassays are a suitable tool for assessing the ecotoxicological relevance of these complex organic mixtures. The proof of biodegradability of the organic load (and its toxicity) can be provided by the Zahn-Wellens test. The environmental safety of water treatment chemicals should be better considered. The combination of the Zahn-Wellens test followed by the performance of ecotoxicity tests turned out to be a cost-efficient suitable instrument for the evaluation of indirect dischargers and considers the requirements of the IPPC Directive.

Background, aim, and scope Chlorinated volatile organic compounds (CVOCs), widely used in industry as solvents and chemical intermediates in the production of synthetic resins, plastics, and pharmaceuticals, are highly toxic to the environment and public health. Various studies reported that Fenton's oxidation could degrade a variety of chlorinated VOCs in aqueous solutions. In acidic conditions, ferrous ion catalyzes the decomposition of H₂O₂ to form a powerful •OH radical. In this study, wastewater from wash of ion-exchange resin containing typical CVOC, 1,2-dichloroethane, was treated using Fenton's oxidation. To reduce environmental load and processing costs of wastewater, Fenton process as a simple and efficient treatment method was applied to degrade 1,2-dichloroethane of wash water. Materials and methods The water samples were collected from three different washing stages of ion-exchange resin. The degradation of 1,2-dichloroethane and total organic carbon (TOC) of wash water of ion-exchange resin by Fenton process was studied with response surface method (RSM). Design of the experiments was conducted by central composite face, and factors included in three models were Fe²⁺ and H₂O₂ doses and treatment time. Relevant quadratic and interaction terms of factors were investigated. Results According to ANOVA, the model predicts well 1,2-dichloroethane reduction of all water samples and TOC reduction of samples 2 and 3. The Fe²⁺ and H₂O₂ doses used in the present study were most suitable when 1,2-dichloroethane concentration of the wash water is about 120 mg L⁻¹. In that case, Fenton's oxidation reduced 1,2-dichloroethane and TOC up to 100% and 87%, respectively, according to the RSM model. With 90-min reaction time and H₂O₂ dose of 1,200 mg L⁻¹, the required Fe²⁺ doses for 1,2-dichloroethane and TOC were 300 and 900 mg L⁻¹, respectively. The optimal H₂O₂/Fe²⁺ stoichiometric molar ratio was between 4-6. Then, concentration of Fe²⁺ was low enough and the amount of residual sludge can thus be reduced. It seems that most of TOC and part of 1,2-dichloroethane were removed by coagulation. Discussion Up to a certain extent, increase of Fe²⁺ and H₂O₂ doses improved the removal of 1,2-dichloroethane and TOC. High Fe²⁺ doses increased the formation of ferric-based sludge, and excessive H₂O₂ doses in sample 2 decreased the degradation of 1,2-dichloroethane. Excess amount of hydrogen peroxide may scavenge hydroxyl radicals, thus leading to loss of oxidative power. Also, the residual hydrogen peroxide of different samples increased with increasing H₂O₂ dose and H₂O₂/Fe²⁺ molar ratio and decreasing treatment time probably also due to scavenging reactions. Due to the saturated nature of 1,2-dichloroethane, the oxidation mechanism involves hydrogen abstraction before addition of hydroxyl radical, thus leading to lower rate constants than for direct hydroxyl radical attack, which for one increases the treatment time. Conclusions Complete removal of 1,2-dichloroethane was attained with initial concentration <120 mg L⁻¹. Also, TOC degraded effectively. Wash water with higher concentration of 1,2-dichloroethane requires longer treatment times and higher concentrations of Fe²⁺ and H₂O₂ for sufficient 1,2-dichloroethane removal. Recommendations and perspectives Due to the results achieved in this study, Fenton's oxidation could be recommended to be used for organic destruction of wash water of ion-exchange resin. Residual sludge, the main disadvantage in Fenton process, can be reduced by optimizing the ferrous dose or by using heterogeneous treatment where most of the reusable iron remains in the solid phase.

Concept and purpose Virtually all water treatment facilities worldwide generate an enormous amount of water treatment residual (WTR) solids for which environmentally friendly end-use options are continually being sought as opposed to their landfilling. Aluminium-based WTR (Al-WTR) can offer huge benefits particularly for phosphorus (P) removal and biofilm attachment when used as media in engineered wetlands. However, potential environmental risks that may arise from the leaching out of its constituents must be properly evaluated before such reuse can be assured. This paper presents results of an assessment carried out to monitor and examine the leachability and leaching patterns of the constituents of an Al-WTR used as media in laboratory-scale engineered wetland systems. Main features, materials and methods Al-WTR was used as media in four different configurations of laboratory-scale engineered wetland systems treating agricultural wastewater. Selected metal levels were determined in the Al-WTR prior to being used while levels of total and dissolved concentration for the metals were monitored in the influent and effluent samples. The increase or decrease of these metals in the used Al-WTR and their potential for leaching were determined. Leached metal levels in the effluents were compared with relevant environmental quality standards to ascertain if they pose considerable risks. Results Aluminium, arsenic, iron, lead and manganese were leached into the treated effluent, but aluminium exhibited the least leaching potential relative to its initial content in the fresh Al-WTR. Levels of P increased from 0.13 mg-P/g (fresh Al-WTR) to 33.9-40.6 mg-P/g (used Al-WTR). Dissolved levels of lead and arsenic (except on one instance) were below the prescribed limits for discharge. However, total and dissolved levels of aluminium were in most cases above the prescribed limits for discharge, especially at the beginning of the experiments. Conclusions, recommendations and perspectives Overall, the study indicates that leaching is observed when Al-WTR is beneficially reused for enhanced P removal in engineered wetlands. In particular, levels of aluminium in the treated effluent beyond the prescribed limits of 0.2 mg/l were observed. However, since the results obtained indicate that aluminium leached is mostly associated with solids, a post-treatment unit which can further reduce the level of aluminium in the treated effluent by filtering out the solids could serve to mitigate this. In addition, plants used in such wetland systems can uptake metals and this can also be a potential solution to ameliorating such metal releases. Periodic monitoring is thus advised. Notwithstanding, the use of Al-WTR as a media in engineered wetlands can serve to greatly enhance the removal of P from wastewaters and also serve as support material for biofilm attachment.

Background, aim and scope Opposite interests must coexist in coastal areas: the presence of significant cities and urban centres, of touristic and recreational areas, and of extensive shellfish farming. To avoid local pollution caused by treated wastewaters along the Northern Adriatic coast (Friuli Venezia-Giulia and Veneto regions), marine outfall systems have been constructed. In this study, the application of a numerical dispersion model is used to support the traditional monitoring methods in order to link information concerning the hydrodynamic circulation and the microbiological features, to evaluate possible health risks associated with recreational and coastal shellfish farming activities. The study is a preliminary analysis of the environmental impact of wastewater treatment plants (WWTPs) with submarine discharge outfalls. It also could be useful for the water profile definition according to the Directive 2006/7/EC on the quality of bathing water and for the integrated areal analysis (Ostoich et al. 2006), to define the area of influence of each submarine discharge point. Materials and methods Historical data on discharges of the considered WWTPs were recovered and evaluated. Data on discharges' control for Veneto region (WWTPs of Lido and Cavallino) were produced by the WWTPs' manager Veritas Laboratory service, while data for the WWTPs of Friuli Venezia-Giulia region were produced by the regional environmental protection agency in the institutional control activity following official methods. The hydrodynamic model used in this work is the three-dimensional version of the finite element model SHYFEM, developed at ISMAR-CNR (Marine Science Institute of the Italian National Research Council) in Venice (Umgiesser et al. J Mar Syst 51:123-145, 2008). Results and discussion Numerical simulations have been carried out with the 3D version of the finite element model SHYFEM for 3 months during autumn 2007 to evaluate the bacterial pollution dispersion along the coasts of Veneto and Friuli Venezia-Giulia regions, prescribing meteo-marine forcings and concentration values at the points corresponding to the positions of the submarine outfalls. Model results show that during autumn 2007 the discharges of the submarine outfalls of the Venice province seem to have no impact on the surface water quality, while there are some visible effects in the Gulf of Trieste. This reflects the behaviour of the experimental data collected by ARPAV and ARPA FVG and monitoring campaigns both on water and shellfish quality. Further results have been elaborated to identify the area of influence of each discharge point; scenarios were developed with imposed concentrations. The results seem to highlight that the two discharges of the Veneto region are not noticeable, while the discharges of the Gulf of Trieste (in particular the Servola and Barcola ones) are perceptible. Conclusions This study represents a new step towards the study of the microbiological pollution dispersion and impact due to the discharges of the submarine outfalls of the Veneto and Friuli Venezia-Giulia regions (nine considered discharge points). With the 3D version of the finite element model SHYFEM, the information obtained from the hydrodynamic circulation has been linked to the classical methods of analysis, to assess possible risks connected to the microbiological parameter Escherichia coli. Recommendations and perspectives In future studies the time scale for microbiological parameters' decay could be linked to various environmental parameters such as light climate, temperature, and salinity. Interesting information would come from the study of new scenarios with different configurations of the discharge of the pipelines and/or the treatment plants and in particular from the improvements of the 3D version of the SHYFEM model, to take the stratification process into account which occurs during spring-summer, since the Northern Adriatic Sea is a very complex ecosystem, both as physical and ecological processes.

Background, aim and scope A newly developed fine bubble aeration system, by which air is transferred under supercavitation conditions, shows a clearly better performance than traditional, well-known aerators that rely on the jet-pump principle and its performance can be compared to oxygen transfer rates achieved in membrane and foil plate aerators. Materials and method A prototype supercavitation aerator installed at a sewage treatment plant revealed an air input rate, which was about one third lower than that of the jet-pump system, which it replaced. Results In spite of this low air input rate, the daily demand of pure oxygen for the additionally installed membrane aeration system went down by approximately 49%, from the original level of about 1,200 m³/day to about 600 m³/day—and this over a test period of more than 7 months. Conclusions and discussion The observed high oxygen transfer rates cannot be explained by traditional mass transfer mechanisms. It is assumed that a large amount of water being transferred into the gas phase by supercavitation contacting directly oxygen also in the gas phase and thereby overcoming mass transfer hindrances which might be favoured by hydroxyl radicals. With this new aerator, during the first 3 months of test phase, already more than 10,000 Euros had been saved because of the reduced pure oxygen demand.

Background, aim, and scope In the Water Framework Directive 2000/60/EC, environmental objectives for the proper quality of inland, surface, transitional, coastal, and ground waters have been set. Member states are required to identify chemical pollutants of significance in the water bodies, to establish emission control measures, and to achieve quality standards. A specific category of pollutants are the compounds that may possess endocrine-related functions known as endocrine disrupting compounds (EDCs). This means that member states have the obligation to take action in order to prevent human exposure to these compounds via aquatic environment. The objective of this research was to study the occurrence and distribution of phenolic and steroid EDCs in inland waters and wastewaters discharged in the area of Thermaikos Gulf, Thessaloniki, Northern Greece. Materials and methods Samples were collected from three rivers, four streams, and four municipal and industrial wastewaters from the area of Thessaloniki, Northern Greece, during the period 2005-2006. The samples were analyzed for 14 EDCs (nonylphenol, octylphenol, their mono- and di-ethoxylate oligomers, bisphenol A, estrone, 17α-estradiol, 17β-estradiol, estriol, mestranol, and 17α-ethynylestradiol). The compounds were recovered by solid phase extraction and ultrasonic extraction from the dissolved phase and particulate phase, respectively, and determined by employing gas chromatography-mass spectrometry. Results Results revealed the presence of phenolic EDCs (NP, NP1EO, NP2EO, tOP, OP1EO, OP2EO, and BPA) in all water and wastewater samples. Steroid EDCs were not found at detectable concentrations. The relationships between field partition coefficients of EDCs and concentration of total suspended solids, dissolved, and particulate organic carbon were investigated. Discussion Rivers exhibited concentrations of EDCs similar to minimally impacted surface waters worldwide. The concentrations of NP and OP occasionally exceeded the environmental quality criteria proposed for inland waters. The concentrations of EDCs in streams exhibited wide variations due to low flow rate in these systems and the impact of wastewaters from various pollution sources. Wastewater from tannery activities showed extremely high concentrations of NP, whereas relatively high concentrations of EDCs were determined in effluents from the industrial wastewater treatment plant. Field partition coefficients of EDCs are negatively correlated with concentrations of total suspended solids and dissolved organic carbon and positively correlated with particulate organic carbon. Conclusions The examined rivers (Aliakmon, Axios, and Loudias) exhibited concentrations of EDCs similar to minimally impacted surface waters worldwide. However, special attention should be paid to these systems since the concentrations for NP and OP occasionally were above the proposed quality standards, revealing the impact of urban, industrial, and agricultural activities. High concentrations of EDCs were determined in streams, urban, and industrial wastewater posing significant risk to the aquatic environment they discharged. Recommendations and perspectives The occurrence of EDCs in inland waters and wastewaters discharged to Thermaikos Gulf results in an increased risk to the marine environment. Thus, these systems should be regularly monitored, especially for NP, OP, and BPA that are considered as priority hazardous compounds in the Water Framework Directive.