Removal efficiency of pharmaceuticals and personal care products with varying wastewater treatment processes and operating conditions - conception of a database and first results.

We created a database in order to quantitatively assess the occurrence and removal efficiency of PPCPs in WWTPs. From 113 scientific publications, we compiled 5887 data on the concentrations and loads of PPCPs in WWTP influents and effluents, and on their removal efficiency. The first outputs of our database include: (1) a list of the most frequently studied molecules, their frequency of detection, their mean concentration and removal in liquid influent and effluent; (2) a comparison of the removal efficiency for different WWTP processes; (3) a study of the influence of the operating conditions (sludge and hydraulic retention times).     

Simultaneous determination of several veterinary pharmaceuticals in effluents from urban, livestock and slaughterhouse wastewater treatment plants using a simple chromatographic method

Minocycline, oxytetracycline, tetracycline, enrofloxacin and ceftiofur, commonly used veterinary pharmaceuticals, were searched in four urban, two livestock and two slaughterhouse effluents from wastewater treatment plants (WWTPs) in the north of Portugal. A simple method that includes solid-phase extraction followed with analysis by high-performance liquid chromatography with diode array detector was established and applied to the simultaneous determination of the five pharmaceuticals in WWTP effluents. This method, which is expeditious, inexpensive and available in most laboratories, showed to be useful for screening for problematic levels of drugs in WWTP effluents. It is known that several livestock and slaughterhouse effluents (pre-treated or treated) are discharged to the urban network before discharge into the environment. The presence of these drugs in such effluents can constitute a significant environmental problem that should be addressed, by the monitoring of these drugs and by implementation of methodologies that contribute to their decrease/elimination from wastewaters. Minocycline (≤6 μg L(-1)), oxytetracycline (≤7 μg L(-1)), tetracycline (≤6 μg L(-1)) and enrofloxacin (<2 μg L(-1)) could be detected and/or quantified in three urban effluents. Detectable levels of enrofloxacin (<2 μg L(-1)) and quantifiable levels of tetracycline (≤15 μg L(-1)) were found in the slaughterhouse effluents.     

Phenol wastewater remediation: advanced oxidation processes coupled to a biological treatment.

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested batch wise, while catalytic wet air oxidation and H2O2-promoted catalytic wet air oxidation processes were studied in a trickle bed reactor, the last two using over activated carbon as catalyst. Effluent characterisation was made by means of substrate conversion (using high liquid performance chromatography), chemical oxygen demand and total organic carbon. Biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) were obtained from respirometric tests using activated sludge from an urban biological wastewater treatment plant (WWTP). The main goal was to find the proper conditions in terms of biodegradability enhancement, so that these phenolic effluents could be successfully treated in an urban biological WWTP. Results show promising research ways for the development of efficient coupled processes for the treatment of wastewater containing toxic or biologically non-degradable compounds.     

Emissions of perfluorinated alkylated substances (PFAS) from point sources--identification of relevant branches

Effluents of wastewater treatment plants are relevant point sources for the emission of hazardous xenobiotic substances to the aquatic environment. One group of substances, which recently entered scientific and political discussions, is the group of the perfluorinated alkylated substances (PFAS). The most studied compounds from this group are perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS), which are the most important degradation products of PFAS. These two substances are known to be persistent, bioaccumulative and toxic (PBT). In the present study, eleven PFAS were investigated in effluents of municipal wastewater treatment plants (WWTP) and in industrial wastewaters. PFOS and PFOA proved to be the dominant compounds in all sampled wastewaters. Concentrations of up to 340 ng/L of PFOS and up to 220 ng/L of PFOA were observed. Besides these two compounds, perfluorohexanoic acid (PFHxA) was also present in nearly all effluents and maximum concentrations of up to 280 ng/L were measured. Only N-ethylperfluorooctane sulphonamide (N-EtPFOSA) and its degradation/metabolisation product perfluorooctane sulphonamide (PFOSA) were either detected below the limit of quantification or were not even detected at all. Beside the effluents of the municipal WWTPs, nine industrial wastewaters from six different industrial branches were also investigated. Significantly, the highest emissions or PFOS were observed from metal industry whereas paper industry showed the highest PFOA emission. Several PFAS, especially perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorododecanoic acid (PFDoA) and PFOS are predominantly emitted from industrial sources, with concentrations being a factor of 10 higher than those observed in the municipal WWTP effluents. Perfluorodecane sulphonate (PFDS), N-Et-PFOSA and PFOSA were not detected in any of the sampled industrial point sources.     

Water reuse for urban landscape irrigation: aspersion and health related regulations.

The Mediterranean seaside resort of Le Grau du Roi includes 40 hectares of landscaped areas spray irrigated with river water supplied through a separate network. Wastewater collected from several municipalities is treated in an activated sludge wastewater treatment plant (WWTP) and polished in waste stabilization ponds (WSPs). Planned substitution of treated wastewater for river water is hindered by spray irrigation prohibition within a 100 m distance from houses and recreational areas. WWTP and WSP effluents were monitored for pathogens with a particular attention to Legionella in Spring and Summer 2006. Helminth eggs, salmonellae and enteroviruses were never detected neither in WWTP effluent nor in the ponds. Legionella spp content was slightly higher or of the order of magnitude of river water contents. Regarding Legionella pneumophila contents, WSP effluent did not significantly differ from the river water. E.coli and enterococci contents in WSP effluents complied with the "excellent quality" criteria of the European Directive for coastal bathing waters. Therefore, substituting WSP effluents to river water is unlikely to alter health risks related to spray irrigation and, in this case, the buffer zone required by the French water reuse guidelines appears being short of support.     

Reuse potential analysis on WWTP effluent of industrial parks in Taiwan.

This study examined the reuse potential of the effluents discharged from several unified wastewater treatment plants (WWTPs) of industrial parks in Taiwan, with designed capacity exceeding 10,000 CMD. Parameters were selected based on the relevant reuse purposes. The "potential recycling percentage", R of the WWTP effluent was defined as the maximal percentage of pure water extractable by the "ideal reverse osmosis module" while the RO retentate still met local effluent standards and required no treatment. The analytical results demonstrated that the WWTP effluents had potential for recycling. A pilot plant was installed in one of the WWTPs. The treatment process included a sand filter, an ultrafiltration unit (UF) and a reverse osmosis module (RO). Results of this study demonstrated that the production quantity and quality are stable and appropriate for various purposes, including both industrial and domestic applications.     

SHARON process evaluated for improved wastewater treatment plant nitrogen effluent quality.

New stricter nitrogen effluent standards and increasing influent loads require existing wastewater treatment plans (WWTPs) to extend or optimize. At WWTPs with limited aeration capacity, limited denitrification capacity or shortage of aerobic sludge age, implementation of SHARON to improve nitrogen effluent quality can be a solution. SHARON is a compact, sustainable and cost-effective biological process for treatment of nitrogen-rich rejection waters. At WWTP Rotterdam-Dokhaven and WWTP Utrecht a SHARON has been in operation for several years. For both WWTPs the effect of SHARON on the nitrogen effluent quality has been evaluated. WWTP Rotterdam-Dokhaven has limited aeration capacity. By implementation of SHARON, the ammonia load of the effluent was reduced by 50%. WWTP Utrecht had limited denitrification capacity. The implementation of SHARON improved the effluent nitrate load by 40%. The overall TN removal efficiency increased from 65% to over 75% and strict nitrogen effluents standards (TN = 10 mg N/l) could be reached. Through modelling and supported by full scale practice it has been shown that by implementation of SHARON in combination with enhanced influent pre-treatment, the aerobic sludge age can be extended to maintain total nitrogen removal at lower temperatures.     

An integrated approach for improving the wastewater discharge and treatment systems

Since treatment plants have been built all over Germany during the last decades, the water quality of receiving streams has been improved remarkably. But there are still a lot of quality problems left, which are caused e.g. by combined sewer overflows (CSO), treatment plant effluents or rainwater discharges from separate sewer systems. At present different efforts are undertaken to control sewer systems in order to improve the operation of urban drainage systems or more generally, design processes. The Emschergenossenschaft and Lippeverband (EG/LV) are carrying out research studies, which are focusing on a minimization of total emissions from sewer systems both from wastewater treatment plant (WWTP) effluents and from CSO. They consider dynamic interactions between rainfall, resultant wastewater, combined sewers, WWTP and receiving streams. Therefore, in an advanced wastewater treatment, a model-based improvement of WWTP operation becomes more and more essential, and consequently a highly qualified operational staff is needed. Some aspects of the current research studies are presented in this report. The need and the use of an integrated approach to combine existing model components in order to optimize dynamic management of combined sewer systems (CSS) with a benefit for nature are outlined.     

Effect of chemical and biological treatment on COD fingerprints of textile wastewaters.

Particle size distribution (PSD) via sequential filtration/ultrafiltration was used as the tool for COD fractionation and colour profiling of textile wastewaters before and after treatment. Profiles prior to treatment suggested PSD-based COD fingerprints characteristic for the influents. Treatment efficiencies were determined via comparing the profiles of the effluents from chemical- and biological-treatment to those of the corresponding influents. COD fingerprints of the wastewaters from the textile plants, applying different treatment alternatives, were different especially at the upper size range; yet profiles after treatment were similar, with the soluble fraction (< 2 nm) being almost the only apparent one. Half of the overall COD-removal via chemical treatment was at the particulate- and upper colloidal-ranges, revealing that this alternative was effective at higher ranges, but not at the soluble fraction. In contrast, biological treatment was effective at both ends of size distribution, with total removal at the particulate range and 50% elimination at the soluble portion. Overall colour content and PSD-based colour profiles of the influents were also different. Chemical treatment was successful in removing colour originating from the entire colloidal range, but was not efficient at the soluble fraction. Conversely, colour removal efficiency of biological treatment was moderate throughout the entire size spectrum.     

Pathogen removal efficiency from UASB + BF effluent using conventional and UV post-treatment systems.

The aim of this study was to verify the efficiency of removal of microorganisms in effluents of a Wastewater Treatment Plant (WWTP) comprising an association of a UASB reactor followed by three submerged aerated biofilters (BAF) and one tertiary filter. The WWTP designed to treat domestic wastewater from a population of 1,000 inhabitants showed high removal efficiency for organic matter and suspended solids. Helminth eggs were also efficiently removed from the tertiary effluent and were found in the sludge from the UASB reactor; however, removal of bacteria in this system was very low. To enhance the efficiency of the system, the effluent from tertiary filters was submitted to UV disinfection in a real scale reactor. Our results showed that UV irradiation was very effective at lowering the concentrations of E. coli, thermotolerant coliforms and coliphages to acceptable levels for agricultural reuse. Salmonella spp. and helminth eggs were seeded into the tertiary effluent before passing through the UV reactor. Salmonella was not found in the final effluent, but helminth eggs were not completely inactivated by UV irradiation and viable eggs were detected after 28 d of incubation.     

Nitrogen speciation in wastewater treatment plant influents and effluents-the US and Polish case studies.

The fate of N species, particularly dissolved organic nitrogen (DON), through process trains of a wastewater treatment plant (WWTP) was investigated. In this study, three fully nitrifying plants in Illinois, USA and biological nutrient removal (BNR) plants in northern Poland were sampled for N characterization in the primary and secondary effluents as a function of the particle size distribution. The correlations between dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations were examined. The key findings are that DON becomes significant portion (about 20%) of the effluent N, reaching up to 50% of effluent total N in one of the Polish plants. The DON constituted 56-95% of total ON (TON) in the secondary effluents, whereas in the Polish plants the DON contribution was substantially lower (19-62%) and in one case (Gdansk WWTP) colloidal ON was the dominating fraction (62% of TON). The DOC to DON ratio in the US plants is significantly lower than that in the receiving waters indicating potential for deterioration of receiving water quality. In Polish plants, the influent and effluent C:N ratios are similar, but not in the US plants.     

Particle related fractionation and characterisation of municipal wastewater.

Several studies show that a more detailed characterisation of the particulate matter in municipal wastewater gives a better understanding and prediction of removal efficiencies of physical-chemical treatment techniques and the application of optimal chemical dosages. Such a characterisation should include the distribution of contaminants over various particle sizes. This article describes a method and results of experimental and full-scale investigations, conducted to determine how contaminants in wastewater are distributed over different particle sizes. For this purpose, particle size fractionations of wastewater influents originating from more than thirteen WWTP were carried out. One of these fractionations (WWTP Venray) is shown and interpreted in this article. First, the wastewaters were fractionated into 5 to 6 particle fractions (45, 5.0, 1.0/1.2, 0.45 and 0.1 microm) after which the fractions were analyzed for various water quality parameters like organic components, nutrients, salts, solids and turbidity. Based on the results the effects of removal of the different size fractions on design of the biological treatment and energy balance of a wastewater treatment plant can be assessed. The method also indicates whether a certain wastewater is efficiently treatable with physical-chemical pre-treatment methods. It is concluded wastewater fractionation on particle size is very useful, but that wastewater characteristics and particle size distributions should not be generalised, but have to be interpreted as indications for a certain average wastewater composition. To give more insight into the distribution of contaminants over particle size and the particle removal potential, a specific wastewater fractionation has to be carried out per WWTP.     

Performances of three R-AN-D-N wastewater treatment plants in the Czech Republic.

The evolution of Czech standards requires higher efficiency of nutrient removal from municipal wastewaters. At the beginning of the last decade of 20th century, a new activated sludge configuration called R-AN-D-N process has been described, successfully tested and now largely used at several wastewater treatment plants (WWTP) in the Czech republic. The main feature of the R-AN-D-N process is the introduction of a regeneration zone in sludge recycle, which enables to increase sludge age in the system without any substantial increase in WWTP volume. Performances of three Czech large WWTP with R-AN-D-N configuration have been monitored and compared within a period of one and a half years. The results confirmed excellent nutrient removal efficiency for wastewaters with different proportion between sewage and industrial effluents. Two of three monitored WWTP received wastewaters from breweries (Budweiser and Pilsner Urquell). The settleability of activated sludge from all three WWTP was correct, with SVI values usually ranging from 50 to 150 ml/g. Monitoring of sludge composition indicated proliferation of several filamentous bacteria, particularly types 0581, 0092 and M. parvicella. No severe bulking events were observed. Finally, the operational costs expressed in CZK (Czech crown: 1 CZK = [see symbol in text]0.0322) per cubic metre of treated sewage or per capita amounts respectively from 2.24 to 6.52, and from 285 to 342.     

Chlorine disinfection of Pseudomonas aeruginosa, total coliforms, Escherichia coli and Enterococcus faecalis: revisiting reclaimed water regulations

Pathogenic organisms can be transmitted orally through drinking water or through skin and mucosae by both direct and indirect contact, and their presence in water thus has a negative impact on public health. In wastewater treatment plants (WWTP), water is disinfected to inactivate pathogens. The quantification of several microbial indicators in aquatic systems is required to estimate the biological quality of such systems. So far, coliform bacteria have been used as traditional indicators world-wide. This study has assessed the resistance of total coliforms, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis to three dosages of sodium hypochlorite (NaClO) at two exposure times. The bacteria were isolated from secondary effluents of a WWTP located in Hidalgo, Mexico. The results show that the number of colony-forming units of all studied bacterial types decreased when both the NaClO concentration and exposure times increased. However, they were not eliminated. The inclusion of the species Pseudomonas aeruginosa in regulations for treated wastewater quality as a new indicator is highly recommended due to its importance as an opportunistic pathogen. The detection of this species along with the traditional organisms could be particulary significant for reclaimed water to be used with direct human contact.     

Fate of oestrogenic compounds and identification of oestrogenicity in a wastewater treatment process.

Understanding of the fate of oestrogen and oestrogenic compounds is important in improving the removal efficiency for oestrogens in wastewater treatment plants (WWTPs). In this study an attempt was made to clarify the fate of oestrogen, oestrogen sulphates, and oestrogenic compounds (synthetic oestrogen, nonylphenol and its relatives) by an instrumental analysis, and the fate of oestrogenicity by an in vitro assay. The investigation was conducted in an activated sludge WWTP in winter and summer, focusing on identification of the primary substances that induce oestrogenicity. Wastewater samples were analysed by employing the silica-gel fractionation technique in conjunction with two-step column chromatography. The results revealed that, in winter, the WWTP efficiencies for the removal of nitrogen and oestrogens decreased and the oestrone level increased with the progress of the treatment. Oestrone and oestrogenic substances are likely to circulate between the aeration tank and the final sedimentation tank. In summer, however, these compounds were effectively removed in the WWTP. The results of the column chromatography coupled with the bioassay suggested that E1 and E2 are the predominant contributors to the oestrogenicity in the influent, return sludge and effluent of the WWTP. The measurement by the instrumental analysis supported these findings.     

Activated sludge wastewater treatment plants optimisation to face pollution overloads during grape harvest periods.

The principal objective of our study was to optimise a municipal activated sludge wastewater treatment plant (WWTP) to face high organic flows due to viticulture effluents inputs. Treatment file optimization consisted in testing different treatment lines, changing the number and volume of biological basins and clarifiers, with or without a buffer basin upstream, with a view to achieving a better reduction of COD. The actual WWTP biological stage is composed of two aerated basins whose total volume is 1365 m3. The studied cases are successively, the installation of a single basin of 1365 m3, then of several basins whose total volume remains constant and equal to 1365 m3. Another case was also considered, that of an aerated basin followed by a first clarifier and then, by another aerated basin and a second clarifier. All scenarios presented below were evaluated, for standard dry weather conditions and for high organic load conditions, as encountered during the grape harvest period. The method used was to carry out various simulations, using numerical modelling, and to compare the impact of different process line scenarios and management strategies on the activated sludge WWTP efficiencies.     

Low effluent nutrient technologies for wastewater treatment.

The USEPA (2001) water quality nutrient criteria will have a significant impact on water pollution control industry due to stringent N and P requirements. This paper presents an update of findings on successful total N (TN) and total P (TP) technologies being implemented at existing wastewater treatment plants (WWTP) to achieve low TN and TP effluents and some key challenges in achieving lower levels. Plants consistently achieving <5 mg TN/L and < 0.5 mg TP/L were identified from a worldwide literature search and plant data collection. Technology gaps and research needs to improve successful technologies to achieve very low TN and TP effluents are summarised in this paper. The dissolved and colloidal organic N have been identified as major challenges in achieving very low levels of TN. Technical and economic challenges to achieve very low TP effluents include alkalinity deficiency, high chemical usage, high sludge production and lack of sufficient influent BOD for biological P uptake.     

Effluent treatment by multi-media filtration, microfiltration and ultrafiltration: results of a pilot investigation at WWTP Hoek van Holland.

Upgrading of wastewater treatment plant (WWTP) effluent as a part of the Dutch governmental policy to close the water cycle has increasing interest now. The Water Board Hoogheemraadschap van Delfland together with the project team of Witteveen + Bos Consulting Engineers, Delft University of Technology and Rossmark water treatment investigated the reuse possibilities of WWTP effluent in the region of Delfland. Therefore pilot research was carried out at WWTP Hoek van Holland applying different filtration techniques: multi-media filtration, micro- and ultrafiltration. The results show stable process performances of the different filtration techniques when proper pre-treatment was applied. For microfiltration the filtration characteristics were strongly influenced by particles which were not retained in the multi-media filter. For ultrafiltration the filtration characteristics were strongly influenced by organic components < 0.2 microm. The upgraded WWTP effluent could not be used directly as process water or for agriculture purposes, due to high concentrations of COD and salts in the WWTP effluent and filtrates. However WWTP effluent or floc filtrate could be applied directly as water for the washing of sea-sand.     

Assessing the elimination of estrogenic activity in advanced wastewater treatment with a reporter gene-based bioassay.

Estrogen-like chemicals, so-called xenoestrogens, have become a topic of concern because they are potentially capable of disturbing the hormonal balance of wildlife and humans. Effluents of wastewater treatment plants (WWTPs) are presumably the major source of xenoestrogens in the aquatic environment. In this study, we investigated eight WWTPs with respect to their input, elimination efficiency, and output of estrogenic activity by means of a reporter gene-based bioassay. All WWTPs employed activated sludge treatment with nitrification/denitrification and tertiary treatment (second nitrification and/or filtration). Estradiol equivalents (EEQs) in the influents of the WWTPs were between 5.7 and 65.8 ng/L. The greatest inputs were found in plants treating pure domestic sewage and in samples collected in winter. Process waters either had no estrogenic activity or EEQs in the range of raw sewage, depending on the source of the process water. EEQs of effluents ranged from mostly below quantification limit (0.8 ng/L) to a maximum of 5.4 ng/L in secondary and 1.4 ng/L in tertiary effluents. These findings demonstrate the elimination efficiency of the activated sludge treatment and the further improvement by additional tertiary treatment. However, several concentrated effluents elicited little, but detectable estrogenic responses in the bioassay.