Search

Limitations of the operation of down-flow sand filters were investigated without and with dosages of methanol, ethanol, or acetate for denitrification and dosages of ferrous sulphate to remove phosphorous. The dynamic head loss was developed due to clogging by suspended solids (SS) that originated from the secondary sedimentation tanks including sludge overflow and from SS in primary settled wastewater that bypassed the biological step. The dynamic head loss was also developed from clogging by gas bubbles formed during denitrification, not by the SS produced from cell growth. The dynamic head loss in sand filters after 24 h operation without and with denitrification increased by 0.9–1.3 and 2.3–2.4 mH2O, respectively. The total time of operation was prolonged by 50% after one water bumping, by 75% after two bumpings, and by 85% after six or seven bumpings. Operational time for filter cycles was prolonged by 4–5 h by one bumping in the full-scale and pilot-scale filters. The time of operation depended on hydraulic loading. With a carbon source dosage, one filter cycle lasted 20–40 h at 10 m/h and 60 h at 5 m/h in pilot-scale filters, and 15–27 h at 3.3 m/h in full-scale filters., QC 20230822

Multiple linear regression (MLR) was applied to study the operation and efficiency of simultaneous denitrification with sodium acetate (NaAc) as a carbon and energy source and the chemical precipitation of phosphate with iron salts in a pilot sand filter. Different loads were simulated with the addition of primary settled wastewater (PW) containing suspended solids (SS) and biological SS from the aeration tank. SS from PW partly passed the filter. Biological SS was caught by the filter. The validation of the model showed that phosphorus concentration and chemical oxygen demand reduction were easier to predict correctly than the time of operation of the filter. The reduction of total phosphorus differed between 0.01 and 0.31 mg P/L, and the nitrate concentration in the filtrate differed between 0 and 5.2 mg N/L when comparing the experimental values with the model. Experiments showed filtrate concentrations of 0–0.12 mg PO4-P/L, 3.0–8.8 mg NO3-N/L, and 1.9–34 mg SS/L. The addition of NaAc gave a small increase in the reduction of PO4-P probably because of the assimilation of PO4-P into the denitrifying sludge. The dosage of Fe gave a small decrease in the reduction of NO3-N probably because of PO4-P limitation for denitrifying bacteria, as Fe acts as a precipitation agent upon PO4-P., QC 20230627

Dual media sand filters at Henriksdal WWTP began to show high head loss after five years of operation, especially during the fluidization for sorting the filter bed after backwashing. At that time, the filters were still clean and the dynamic head loss, due to clogging of the filters with suspended solids during a cycle of operation, had its lowest value. Dynamic head loss over the lower sand layer surface in the dual media sand filter was detected in some filter cycles of operation. The initial head loss in the filters has increased over the years. This type of head loss is constant during a cycle of operation and increases only slowly with time. It is due to different factors, as precipitation of ferric oxide hydroxide in the nozzle slots and on the grains in the filter bed, and accumulation of filter bed grains below the filter bottom. Different measures were tested to reduce or eliminate the initial head loss in the filters. Results from frequency diagrams showed that changing nozzles and removing of filter bed material from below the filter bottom were the most favourable actions. Backwashing more frequently and with more sequences also reduced the initial head loss., QC 20230908

Several micropollutants show low removal efficiencies in conventional sewage treatment plants, and therefore enter the aquatic environment. To reduce the levels of micropollutants in sewage effluent, and thereby the effects on biota, a number of extra treatment steps are currently being evaluated. Two such techniques are ozonation and adsorption onto activated carbon. In this study, we investigated the efficiency of Sweden's first full-scale ozonation treatment plant at removing a number of antibiotics, antimycotics and biocides. The effect of adding granular activated carbon (GAC) on a pilot scale and pilot-scale ozonation were also evaluated. The conventional treatment (13,000 PE) with the add-on of full-scale ozonation (0.55 g O-3/g Total organic carbon (TOC)) was able to remove most of the studied compounds (>90%), except for benzotriazoles and fluconazole (<50%). Adsorption on GAC on a pilot scale showed a higher removal efficiency than ozonation (>80% for all studied compounds). Three types of GAC were evaluated and shown to have different removal efficiencies. In particular, the GAC with the smallest particle sizes exhibited the highest removal efficiency. The results demonstrate that it is important to select an appropriate type of carbon to achieve the removal goal for specific target compounds., QC 20181024

The consumption of pharmaceuticals worldwide coupled with modest removal efficiencies of sewage treatment plants have resulted in the presence of pharmaceuticals in aquatic systems globally. In this study, we investigated the environmental concentrations of a selection of 93 pharmaceuticals in 43 locations in the Baltic Sea and Skagerrak. The Baltic Sea is vulnerable to anthropogenic activities due to a long turnover time and a sensitive ecosystem in the brackish water. Thirty-nine of 93 pharmaceuticals were detected in at least one sample, with concentrations ranging between 0.01 and 80 ng/L. One of the pharmaceuticals investigated, the anti-epileptic drug carbamazepine, was widespread in coastal and offshore seawaters (present in 37 of 43 samples). In order to predict concentrations of pharmaceuticals in the sub-basins of the Baltic Sea, a mass balance-based grey box model was set up and the persistent, widely used carbamazepine was selected as the model substance. The model was based on hydrological and meteorological sub-basin characteristics, removal data from smaller watersheds and wastewater treatment plants, and statistics relating to population, consumption and excretion rate of carbamazepine in humans. The grey box model predicted average environmental concentrations of carbamazepine in sub-basins with no significant difference from the measured concentrations, amounting to 0.57-3.2 ng/L depending on sub-basin location. In the Baltic Sea, the removal rate of carbamazepine in seawater was estimated to be 6.2 10(-9) s(-1) based on a calculated half-life time of 3.5 years at 10 degrees C, which demonstrates the long response time of the environment to measures phasing out persistent or slowly degradable substances such as carbamazepine. Sampling, analysis and grey box modelling were all valuable in describing the presence and removal of carbamazepine in the Baltic Sea., QC 20180516

Pharmaceutical residues and other micro-contaminants may enter aquatic environments through effluent from sewage treatment plants (STPs) and could cause adverse effects in wild fish. One strategy to alleviate this situation is to improve wastewater treatment by ozonation. To test the effectiveness of full-scale wastewater effluent ozonation at a Swedish municipal STP, the added removal efficiency was measured for 105 pharmaceuticals. In addition, gene expression, reproductive and behavioral endpoints were analyzed in zebrafish (Danio rerio) exposed on-site over 21 days to ozonated or non-ozonated effluents as well as to tap water. Ozone treatment (7 g O3/m3) removed pharmaceuticals by an average efficiency of 77% in addition to the conventional treatment, leaving 11 screened pharmaceuticals above detection limits. Differences in biological responses of the exposure treatments were recorded in gene expression, reproduction and behavior. Hepatic vitellogenin gene expression was higher in male zebrafish exposed to the ozonated effluent compared to the non-ozonated effluent and tap water treatments. The reproductive success was higher in fish exposed to ozonated effluent compared to non-ozonated effluent and to tap water. The behavioral measurements showed that fish exposed to the ozonated STP effluent were less active in swimming the first minute after placed in a novel vessel. Ozonation is a capable method for removing pharmaceuticals in effluents. However, its implementation should be thoroughly evaluated for any potential biological impact. Future research is needed for uncovering the factors which produced the in vivo responses in fish., QC 20180529

Sewage contains a mixed ecosystem of diverse sets of microorganisms, including human pathogenic viruses. Little is known about how conventional as well as advanced treatments of sewage, such as ozonation, reduce the environmental spread of viruses. Analyses for viruses were therefore conducted for three weeks in influent, after conventional treatment, after additional ozonation, and after passing an open dam system at a full-scale treatment plant in Knivsta, Sweden. Viruses were concentrated by adsorption to a positively charged filter, from which they were eluted and pelleted by ultracentrifugation, with a recovery of about 10%. Ion Torrent sequencing was used to analyze influent, leading to the identification of at least 327 viral species, most of which belonged to 25 families with some having unclear classification. Real-time PCR was used to test for 21 human-related viruses in inlet, conventionally treated, and ozone-treated sewage and outlet waters. The viruses identified in influent and further analyzed were adenovirus, norovirus, sapovirus, parechovirus, hepatitis E virus, astrovirus, pecovirus, picobirnavirus, parvovirus, and gokushovirus. Conventional treatment reduced viral concentrations by one to four log10, with the exception of adenovirus and parvovirus, for which the removal was less efficient. Ozone treatment led to a further reduction by one to two log10, but less for adenovirus. This study showed that the amount of all viruses was reduced by conventional sewage treatment. Further ozonation reduced the amounts of several viruses to undetectable levels, indicating that this is a promising technique for reducing the transmission of many pathogenic human viruses., QC 20180727

Traces of active pharmaceutical ingredients (APIs) and other chemicals are demonstrated in effluents from sewage treatment plants (STPs) and they may affect quality of surface water and eventually drinking water. Treatment of effluents with granular activated carbon (GAC) or ozone to improve removal of APIs and other contaminants was evaluated at two Swedish STPs, Käppala and Uppsala (88 and 103 APIs analyzed). Biomarker responses in rainbow trout exposed to regular and additionally treated effluents were determined. GAC and ozone treatment removed 87–95% of the total concentrations of APIs detected. In Käppala, GAC removed 20 and ozonation (7 g O3/m3) 21 of 24 APIs detected in regular effluent. In Uppsala, GAC removed 25 and ozonation (5.4 g O3/m3) 15 of 25 APIs detected in effluent. GAC and ozonation also reduced biomarker responses caused by unidentified pollutants in STP effluent water. Elevated ethoxyresorufin-O-deethylase (EROD) activity in gills was observed in fish exposed to effluent in both STPs. Gene expression analysis carried out in Käppala showed increased concentrations of cytochrome P450 (CYP1As and CYP1C3) transcripts in gills and of CYP1As in liver of fish exposed to effluent. In fish exposed to GAC- or ozone-treated effluent water, gill EROD activity and expression of CYP1As and CYP1C3 in gills and liver were generally equal to or below levels in fish held in tap water. The joint application of chemical analysis and sensitive biomarkers proved useful for evaluating contaminant removal in STPs with new technologies., QC 20170613

In this study a Partial Least Squares Projection of Latent Structures (PLS) model has been developed for predicting the rejection of pharmaceutical residuals by nanofiltration (NF) using treated municipal wastewater as feed. The objective was to provide a practical tool for wastewater reuse facilities for estimating the rejection of emerging organic contaminants based on their physiochemical characteristics. The model was developed by identifying the important physiochemical properties of pharmaceutical residuals for rejection by NF. The investigated pharmaceuticals were those present in the effluent from Henriksdal wastewater treatment plant (WWTP), Sweden. The rejection, at volume reduction factors (VRF) ranging from 2 to 20, was examined in a NF pilot plant at two occasions. The important variables for rejection by NF were, in descending order: polarizability, globularity, ratio hydrophobic to polar water accessible surface area and compound charge. Two studies were performed with a time interval of about a year with different wastewater matrices and age of membranes. For different VRFs, but in the same study, the model produced consistent predicted rejections. For the same VRF, but in the different studies, the regression lines were almost parallel, but with a deviation of about 7% for the predicted values. Most of the compounds were within the 95% prediction interval. The model also proved to be able to predict rejection using data from the literature. This confirms that the predictive PLS model can estimate the rejection albeit, with limitations. Generally the proposed predictive rejection model is most likely valid but the model coefficients need to be determined for each individual WWTP or wastewater reuse facility., QC 20170217

Sewage treatment plants (STPs) have repeatedly been suggested as “hotspots” for the emergence and dissemination of antibiotic-resistant bacteria. A critical question still unanswered is if selection pressures within STPs, caused by residual antibiotics or other co-selective agents, are sufficient to specifically promote resistance. To address this, we employed shotgun metagenomic sequencing of samples from different steps of the treatment process in three Swedish STPs. In parallel, concentrations of selected antibiotics, biocides and metals were analyzed. We found that concentrations of tetracycline and ciprofloxacin in the influent were above predicted concentrations for resistance selection, however, there was no consistent enrichment of resistance genes to any particular class of antibiotics in the STPs, neither for biocide and metal resistance genes. The most substantial change of the bacterial communities compared to human feces occurred already in the sewage pipes, manifested by a strong shift from obligate to facultative anaerobes. Through the treatment process, resistance genes against antibiotics, biocides and metals were not reduced to the same extent as fecal bacteria. The OXA-48 gene was consistently enriched in surplus and digested sludge. We find this worrying as OXA-48, still rare in Swedish clinical isolates, provides resistance to carbapenems, one of our most critically important classes of antibiotics. Taken together, metagenomics analyses did not provide clear support for specific antibiotic resistance selection. However, stronger selective forces affecting gross taxonomic composition, and with that resistance gene abundances, limit interpretability. Comprehensive analyses of resistant/non-resistant strains within relevant species are therefore warranted.

This paper presents 10 recommendations for improving the European Medicines Agency's guidance for environmental risk assessment of human pharmaceutical products. The recommendations are based on up-to-date, available science in combination with experiences from other chemical frameworks such as the REACH-legislation for industrial chemicals. The recommendations concern: expanding the scope of the current guideline; requirements to assess the risk for development of antibiotic resistance; jointly performed assessments; refinement of the test proposal; mixture toxicity assessments on active pharmaceutical ingredients with similar modes of action; use of all available ecotoxicity studies; mandatory reviews; increased transparency; inclusion of emission data from production; and a risk management option. We believe that implementation of our recommendations would strengthen the protection of the environment and be beneficial to society. Legislation and guidance documents need to be updated at regular intervals in order to incorporate new knowledge from the scientific community. This is particularly important for regulatory documents concerning pharmaceuticals in the environment since this is a research field that has been growing substantially in the last decades., QC 20150615

QC 20140109

Treated sewage effluents contain complex mixtures of micropollutants, raising concerns about effects on aquatic organisms. The addition of advanced treatment steps has therefore been suggested. However, some of these could potentially produce effluents affecting exposed organisms by unknown modes of action. Here, 1H NMR (proton nuclear magnetic resonance spectroscopy) metabolomics of fish blood plasma was used to explore potential responses not identified by more targeted (chemical or biological) assays. Rainbow trout was exposed in parallel to six differently treated effluents (e.g., conventional activated sludge, addition of sand filter, further addition of ozonation and/or a moving bed biofilm reactor or a separate membrane bioreactor line). Multivariate data analysis showed changes in the metabolome (HDL, LDL, VLDL and glycerol-containing lipids, cholesterol, glucose, phosphatidylcholine, glutamine, and alanine) between treatment groups. This formed the basis for postulating a hypothesis on how exposure to effluent treated by certain processes, including ozonation, would affect the metabolic profiles of exposed fish. The hypothesis withstood testing in an independent study the following year. To conclude, 1H NMR metabolomics proved suitable for identifying physiological responses not identified by more targeted assays used in parallel studies. Whether these changes are linked to adverse effects remains to be tested., QC 20120217

A method for the analysis of the artificial sweetener sucralose in sewage water and recipient water was developed. Extraction and clean up was performed with solid-phase extraction utilising Oasis HLB columns. Detection was made by liquid chromatography electrospray mass spectrometry (LC/MS). The triple-quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) mode. However, 'pseudo MRM' was used, a technique where the two quadrupoles monitor the same m/z. The sodium adduct of sucralose was used for quantification, since lower detection limits were obtained as compared to the sucralose quasi-molecular ion in negative ion mode. The two ions with highest intensity in the chlorine isotope pattern were monitored. The reduction of matrix effects with this approach is discussed. The method limit of quantification (MLOQ) for sewage water was 0.2 mu g L(-1), whereas for recipient water MLOQ was 0.02 mu g L(-1). The method was used to analyse effluent samples from an experimental sewage treatment plant (STP) to assess the efficiency of tertiary treatment techniques for removal of sucralose. Filtration through activated carbon was shown to be efficient, while ozonation, advanced oxidation techniques and membrane bioreactors were less efficient. Analyses of receiving waters showed low dilution of sucralose emitted from the STPs., QC 20120217

Since conventional treatment technologies may fail in removing many micro-pollutants, there is currently a focus on the potential of additional treatment technologies for improved sewage treatment. The aim of the present study was to evaluate six different effluents from Henriksdal Sewage Treatment Plant in Stockholm, Sweden. The effluents were; conventionally treated effluent (chemical phosphorous removal in combination with an activated sludge process, including biological nitrogen removal and a sand filter), with additional treatments individually added to the conventional treatment; active carbon filtration, ozonation at 5 mg l(-1), ozonation at 15 mg l(-1), ozonation at 5 mg l(-1) + moving bed biofilm reactor and irradiation with ultraviolet radiation + hydrogen peroxide. The evaluation was done by characterizing and comparing the effluents using a Lefkovitch matrix model based on a life cycle test with the harpacticoid copepod Nitocra spinipes, combined with analysis of juvenile development and survival over time. The conventionally treated effluent resulted in the most negative effects, leading to the conclusion that all additional treatments in the present study created effluents with less negative impacts on the copepod populations. The ozone treatments with the low dose treatment in particular, resulted in the overall least negative effects. Moving bed biofilm reactor combined with ozone did not improve the quality of the effluent in the sense that slightly more negative effects on the population abundance were seen for this treatment technology compared to ozonation alone. The active carbon treatment had more negative effects than the ozone treatments, most of which could possibly be explained by removal of essential metal ions. The effluent which was treated with ultraviolet radiation + hydrogen peroxide resulted in few developmental and survival effects over time, but still showed negative effects on the population level. Matrix population modeling prov, QC 20120217

In the present study, two conventional (with and without sand filter) and four additional (moving bed biofilm reactor, ozone, moving bed biofilm reactor combined with ozone and a membrane bio reactor) treatment technologies were operated in small-scale at Hammarby Sjostad sewage treatment plant, Stockholm, Sweden. The effluents were tested with five short-term ( <= 7 days exposure) ecotoxicological tests, and analyzed for a number of target analytes, comprising pharmaceuticals, natural hormones and industrial chemicals. Overall, the tested effluents generated few adverse effects at lower concentrations ( < 50% sewage effluent), and no major differences were observed between any of the treatments. The effluent treated with the moving bed biofilm reactor resulted in the lowest effects in the ecotoxicological tests. The most efficient treatment technology with regard to the pharmaceutical residues was the ozone treatment, which however caused negative effects in some of the ecotoxicological tests., QC 20120217

The objective of this study was to evaluate the potential of nanofiltration (NF) and ozonation for indirect potable reuse in terms of pharmaceutical residuals. To simultaneously obtain a reasonable retentate volume for further treatment, the tests were performed at a high volume reduction factor (VRF) of 60. The feed to the pilot plant was the effluent from a BNR plant with a final process step of chemical precipitation and rapid sand filtration. Two tests were performed 1) nanofiltration of treated wastewater followed by ozonation and 2) ozonated treated wastewater as feed to NF. Of the 95 pharmaceuticals analysed, three were not removed to the quantification limit, oxazepam in the first test and glibenclamide and ketoprofen in the second. The water quality after the two processes was similar, with an overall removal of pharmaceutical residuals of 99%. There are two advantages of ozonated water as feed to NF-a higher specific flux of 35% and a potential removal of ozonation by-products. The retention of some pharmaceuticals by NF was lower than anticipated, the major removal occurring in the ozonation. A tighter NF or RO is required in order to achieve higher pharmaceutical retention for further treatment of the retentate., QC 20120217

QC 20120217

Treated sewage effluents often contain a mixture of estrogenic compounds in low concentrations. The total combined activity of these, however, may be sufficiently high to affect the reproduction of aquatic vertebrates. The introduction of advanced treatment technologies has been suggested as a way to remove micro-contaminants, including estrogenic substances. In this study, one municipal influent was treated with six different processes in parallel on a semi-large scale in order to assess their potential to reduce substances that could contribute to estrogenic effects in male fish. The effluent from a conventional, activated sludge treatment line was compared to a similarly treated effluent with a final sand-filtering step. The addition of ozonation (15 g O3/m3), a moving bed biofilm reactor (MBBR) or both in combination was also evaluated. There was also a separate treatment line that was based on a membrane bioreactor. A small battery of hepatic estrogen-responsive genes was measured in the exposed fish using quantitative PCR. Concentrations of steroid estrogens and estrogenic phenols in the effluents were measured by GC-ECNI-MS. The ozonated effluents were the only tested effluents for which all measured biological effects in exposed fish were removed. Chemical data suggested that the MBBR technology was equally effective in removing the analyzed estrogens; however, elevated expression of estrogen-responsive genes suggested that some estrogenic substances were still present in the effluent. The membrane bioreactor removed most of the measured estrogens and it reduced the induction of the estrogen-responsive genes. However, fish exposed to this effluent had significantly enlarged livers. Given that the same influent was treated in parallel with a broad set of technologies and that the chemical analyses were combined with an in vivo assessment of estrogenic responses, this study provides valuable input into the assessment of advanced treatment processes for removin, QC 20120217

QC 20120426

QC 20120217

In this paper, a simulation benchmark of a pre-denitrifying activated sludge process is utilized in order to evaluate a supervisory aeration volume control strategy. The aeration volume control strategy has also been evaluated in a pilot plant at Hammarby Sjostad in Stockholm, Sweden. The main idea has been to let the dissolved oxygen (DO) concentration in some of the aerated compartments be determined by a higher level controller driven by the DO concentration in other compartments. In this way, only sensors for measuring the DO concentrations are needed for the decision of time varying DO set-points. The high reliability of such sensors implies robust input values for the proposed control strategy. Moreover, it is known that the respiration rate is affected by the content of substrate and nitrogen in the compartments; therefore, the suggested manipulations of the DO set-points are indirectly determined by the current load into the plant. Compared to constant DO control and a supervisory DO set-point control strategy based on ammonium measurements in the last aerobic compartment, the suggested aeration volume control strategy could reduce the effluent nitrate and ammonium concentrations significantly without increasing the aeration energy., QC 20120313

The aim of this study was to investigate variations in the occurrence and removal of enterovirus and norovirus genomes, Giardia cysts, Cryptosporidium oocysts and the most commonly used faecal indicators in a Swedish wastewater pilot plant. Paired samples were taken from the inlet and outlet of each treatment line: tertiary filtration, membrane bioreactor (MBR) and upflow anaerobic sludge blankets (UASB). (Oo)cysts and indicators were enumerated using standard methods and viruses using RT-PCR. Giardia cysts and enteroviruses were constantly detected, mean numbers 10(3.11) cysts and 10(4.0) PCR units L-1, respectively. Oocysts were found in 5/19 samples, mean number 5 L-1. Noroviruses were found in 6/7 influent samples, with an average titre of 10(3 28) L-1, during winter, but only in 2/15 in the rest of the year (mean 200 L-1). MBR treatment removed indicators more efficiently than did the other two lines, with 5 log removal of E. coli. Human virus genome removal did not differ between the MBR and tertiary treatment line. Microorganism removal in UASB was significantly lower for all the organisms studied. E. coli, enterococci and Cl. perfringens removal was correlated (p < 0.05) with enterovirus genome removal, with R-values around 0.4. However, values for removal of indicators were more strongly correlated to each other. Removal of viruses based on enumeration using RT-PCR probably underestimates infectious virion removal., QC 20101013. Updated from manuscript to article in journal.

NQC