Treated Sewage Effluent Research Articles

Monitoring and modelling of siloxanes in a sewage treatment plant in the UK

Monitoring of cyclic volatile methylsiloxanes (cVMS) carried out at Anglian Water’s Broadholme sewage treatment plant (STP) is described. The method deployed used headspace gas chromatography/mass spectrometry (HS-GC/MS) and the addition of isotopically labelled cVMS to correct for partitioning in samples containing high levels of particulate and dissolved organic carbon. The method was capable of measuring cVMS in raw sewage samples, with recoveries of 80%, 85% and 71% respectively, for D4, D5 and D6. The limit of quantification was 0.2μgL−1 for all three substances. Recoveries close to 100% were observed for all cVMS spiked into treated effluent (LOQ=0.01μgL−1). Despite the volatile nature of cVMS and its ubiquitous presence in the ambient atmosphere, the methods deployed showed excellent recoveries, reproducibility and quantification limits. A distinct diurnal variation in cVMS concentration, probably linked with the use of personal care products was observed for raw sewage but not in treated sewage effluent. The estimated per capita consumption of D5 (∼2.7mgcap−1d−1) derived for the population served by this plant was significantly lower than that derived in the Environment Agency (UK) risk assessment (11.6mgcap−1d−1). The cVMS were highly removed during sewage treatment with efficiencies greater than 98%. The methods and findings of this pilot study can be used as the basis for future studies on the fate of cVMS substances in STPs.

Short communication: Rapid <i>in vitro</i> tests to determine the toxicity of raw wastewater and treated sewage effluents

Wastewater consists of a complex mixture of substances. During wastewater treatment these harmful substances can be eliminated or degraded. However, persistent compounds released with the treated sewage effluents enter the environment and pose a risk to animal and human life. To determine the potential risks involved, screening tests are needed to monitor wastewater for potential toxic contaminants. The aim of this study was to validate and use screening tests to determine the toxicity of raw wastewater and treated sewage effluents from 3 sewage treatment plants in the Western Cape, South Africa. Raw wastewater and treated sewage effluents were screened for cytotoxicity using lactate dehydrogenase (LDH) release from cells as biomarker, for neurotoxicity using acetylcholinesterase (AChE) inhibition and for genotoxicity using the Save Our Soul (SOS) test. Results showed no cytotoxicity for both raw wastewater and treated sewage effluents from all sewage treatment plants. Raw wastewater from all sewage treatment plants contained AChE inhibitors and sewage treatment processes were not effective at eliminating these AChE inhibitors. Raw wastewater from all sewage treatment plants tested positive for genotoxicity. Treated sewage effluents from all three sewage treatment plants displayed no genotoxicity indicating effective removal of genotoxins by all three sewage treatment plants investigated.

Holocene fluvial responses to external drivers in the Northwestern Mediterranean Africa: contributions of the study of Oued Sebou in the Gharb alluvial plain (Morocco)

In a field experiment performed in Lins County (São Paulo State, Brazil), treated sewage effluent (TSE) irrigation increased sugarcane yield but caused an excessive increase in the exchangeable sodium percentage (ESP) and clay dispersion after 16 months due to an intense irrigation regime (2500 mm/16 months) with sodium rich effluents. After two additional complete cycles with lower TSE irrigation rates (1200 mm year−1), 1700 kg ha−1 of phosphogypsum was added to a section of the irrigated plots to evaluate its residence time and its implications on Na+ dynamics and other soil properties. Undisturbed soil cores were taken 2 years after phosphogypsum application to verify soil physical properties up to 0.2 m depth, and disturbed soil samples were taken every year up to 1 m depth for chemical analyses. After 5 years of consecutive TSE irrigation (2005–2010), soil acidity (pH ≈ 5) and basic cations (Ca ≈ 12, Mg ≈ 6 and K ≈ 2 mmolc kg−1) were maintained in adequate conditions for plant development without the necessity of liming, while acidity was increased (pH ≈ 4.5) and Ca (≈9 mmolc kg−1), and the Mg (≈4.5 mmolc kg−1) concentration decreased in the rainfed without phosphogypsum treatment. An increase in water retention capacity at −30 (from 0.14 to 0.17 m3 m−3) and −1500 kPa (from 0.08 to 0.12 m3 m−3) potentials was also observed in all TSE irrigated treatments. The plots with a phosphogypsum treatment showed average increases of 2 mmolc kg−1 of Ca2+ and 7 mg kg−1 of S-SO42− in all soil profiles and an average reduction of 2 mmolc kg−1 of Na+ up to 0.4 m from 2008 to 2009. However, the extent of the chemical effects was greater after the first year compared to the second year. The high concentration of Na+ found in previous studies performed in the same area returned to low concentrations after continued TSE irrigation at lower rates, even without the phosphogypsum application. An unusual phosphorus migration was observed to the 0.4–0.8 m soil layer as a result of TSE irrigation, most likely due to a high pH and a Na carbonate-dominated TSE.

Energetic environmental and economic assessment of three tree species and one herbaceous crop irrigated with primary treated sewage effluent

The energetic, environmental, and economic performance of four bioenergy plant species (Αcacia cyanophylla, Eucalyptus camaldulensis, Populus nigra, and Arundo donax), irrigated with pre-treated effluent in a three-year-field trial, was investigated. Results showed that irrigation was more energy demanding compared to other practices. A. cyanophylla achieved 34, 83, and 189% higher above ground biomass energy yield than E. camaldulensis, A. donax, and P. nigra, respectively. A. cyanophylla and E. camaldulensis had higher energy requirements but they achieved higher net energy yield and energy ratio. P. nigra (3.49 € GJ−1) and A. donax (2.34 € GJ−1) were found to have higher energy production cost compared to E. camaldulensis (1.65 € GJ−1) and A. cyanophylla (1.24 € GJ−1). P. nigra and A. donax had the highest nutrient use efficiency for nitrogen (NUE-N) and phosphorus (NUE-P), respectively. It was concluded that species with low NUE, which is opposite to current directions, and high water use efficiency (WUE) (i.e. plant species with relatively low water demands and great biomass allocation in leaves), are more suitable when irrigation with strong effluent occur and N removal is primary objective. Such plant species have comparatively lower energy requirements, which is consistent with the current trend for low energy inputs in agriculture. To mitigate the losses in plant biomass and reduce the adverse environmental impacts from nutrients, additional practices should be adopted. Our results help us to draw important conclusions in order to set criteria in the selection of suitable bioenergy crops and practices.

Soil properties in a sugarcane plantation after the application of treated sewage effluent and phosphogypsum in Brazil

In a field experiment performed in Lins County (São Paulo State, Brazil), treated sewage effluent (TSE) irrigation increased sugarcane yield but caused an excessive increase in the exchangeable sodium percentage (ESP) and clay dispersion after 16months due to an intense irrigation regime (2500mm/16months) with sodium rich effluents. After two additional complete cycles with lower TSE irrigation rates (1200mmyear−1), 1700kgha−1 of phosphogypsum was added to a section of the irrigated plots to evaluate its residence time and its implications on Na+ dynamics and other soil properties. Undisturbed soil cores were taken 2years after phosphogypsum application to verify soil physical properties up to 0.2m depth, and disturbed soil samples were taken every year up to 1m depth for chemical analyses. After 5years of consecutive TSE irrigation (2005–2010), soil acidity (pH≈5) and basic cations (Ca≈12, Mg≈6 and K≈2mmolckg−1) were maintained in adequate conditions for plant development without the necessity of liming, while acidity was increased (pH≈4.5) and Ca (≈9mmolckg−1), and the Mg (≈4.5mmolckg−1) concentration decreased in the rainfed without phosphogypsum treatment. An increase in water retention capacity at −30 (from 0.14 to 0.17m3m−3) and −1500kPa (from 0.08 to 0.12m3m−3) potentials was also observed in all TSE irrigated treatments. The plots with a phosphogypsum treatment showed average increases of 2mmolckg−1 of Ca2+ and 7mgkg−1 of S-SO42− in all soil profiles and an average reduction of 2mmolckg−1 of Na+ up to 0.4m from 2008 to 2009. However, the extent of the chemical effects was greater after the first year compared to the second year. The high concentration of Na+ found in previous studies performed in the same area returned to low concentrations after continued TSE irrigation at lower rates, even without the phosphogypsum application. An unusual phosphorus migration was observed to the 0.4–0.8m soil layer as a result of TSE irrigation, most likely due to a high pH and a Na carbonate-dominated TSE.

Reliability of non-culturable virus monitoring by PCR-based detection methods in environmental waters containing various concentrations of target RNA

Owing to the lack of practical cell culture system for human noroviruses (HuNoV), various detection methods based on conventional reverse transcription-PCR (RT-PCR) and the quantitative real-time PCR have been major tools for monitoring environmental water safety. In this study, we showed that the proportion of water sample concentrates used for one-step RT-PCR significantly influences false-negative findings of the non-culturable viruses. In total, 59 archived samples of previously analyzed water concentrates were reexamined for HuNoV RNA by the one-step RT-PCR and semi-nested PCR. Using new aliquots for RNA extraction for every trial, up to 20 PCR trials were performed for each archive to determine whether the crosscheck results supported the previous determinations. We reconfirmed that 27.6% (8/29) of the samples were HuNoV-positive samples: 6.7% (1/15) from groundwater, 33.3% (3/9) from river water, and 80% (4/5) from treated sewage effluent (TSE). These results corresponded to the ratio of previously negative HuNoV samples now identified as positive (8/30): 6.7% (1/15) from groundwater, 20% (1/5) from river water, and 60% (6/10) from TSE. To elucidate the cause of these results, 16 different concentrations of murine norovirus (MNV) RNA (from 2×10(2) to 8×10(3) copies, divided into 10 tubes for each concentration) were subjected to one-step RT-PCR. The detection frequency and reproducibility decreased sharply when the number of MNV RNA copies fell below threshold levels. These observations suggest that the proportion of water concentrate used for PCR-based detection should be considered carefully when deciding viral presence in certain types of environmental water, particularly in regard with legal controls.

Assessing the Relative Bioavailability of DOC in Regional Groundwater Systems

It has been hypothesized that the degree to which a hyperbolic relationship exists between concentrations of dissolved organic carbon (DOC) and dissolved oxygen (DO) in groundwater may indicate the relative bioavailability of DOC. This hypothesis was examined for 73 different regional aquifers of the United States using 7745 analyses of groundwater compiled by the National Water Assessment (NAWQA) program of the U.S. Geological Survey. The relative reaction quotient (RRQ), a measure of the curvature of DOC concentrations plotted versus DO concentrations and regressed to a decaying hyperbolic equation, was used to assess the relative bioavailability of DOC. For the basalt aquifer of Oahu, Hawaii, RRQ values were low (0.0013 mM(-2)), reflecting a nearly random relationship between DOC and DO concentrations. In contrast, on the island of Maui, treated sewage effluent injected into a portion of the basalt aquifer resulted in pronounced hyperbolic DOC-DO behavior and a higher RRQ (142 mM(-2)). RRQ values for the 73 aquifers correlated positively with mean concentrations of ammonia, dissolved iron, and manganese, and correlated negatively with mean pH. This indicates that greater RRQ values are associated with greater concentrations of the final products of microbial reduction reactions. RRQ values and DOC concentrations were negatively correlated with the thickness of the unsaturated zone (UNST) and depth to the top of the screened interval. Finally, RRQ values were positively correlated with mean annual precipitation (MAP), and the highest observed RRQ values were associated with aquifers receiving MAP rates ranging between 900 and 1300 mm/year. These results are uniformly consistent with the hypothesis that the hyperbolic behavior of DOC-DO plots, as quantified by the RRQ metric, can be an indicator of relative DOC bioavailability in groundwater systems.

Treated sewage effluent: Agronomical and economical aspects on bermudagrass production

This study investigated the effects of irrigation using treated sewage effluent (TSE) combined with nitrogen (N) fertilization on the productivity and quality of bermudagrass, and on its economic feasibility under tropical conditions. The treatments employed were SI – no irrigation and no fertilization; A100 (control) – irrigation with potable water plus 520kgNha−1year−1 provided as NH4NO3; E0, E33, E66, and E100: irrigation with treated sewage effluent plus 0, 172, 343 and 520kgNha−1year−1 as NH4NO3, respectively. Chemical properties of TSE, shoot dry matter production, N concentration in bermudagrass were determined, and benefit–cost and economic viability analyses were carried out. Tree years of irrigation with TSE had agronomical benefits to bermudagrass such as: (i) saving 33% in N fertilizer by adding of 275kgNha−1year−1, increasing N accumulation in the soil; (ii) providing 70% of the N as NH4+, which is the form most quickly assimilated by the plants; (iii) building up dry matter production with 7Mgha−1year−1 and (iv) increasing leaf N concentration in leaf tissue. The main benefit of TSE irrigation occurs in drought seasons with the increase in N concentration in bermudagrass shoots. Higher N concentration in leaf tissue elevates the quality and the sales price for the grass harvested, thus optimizing the benefit–cost ratio for the producer. Therefore, TSE irrigation is a viable cost-effective alternative if the N concentration in the leaf tissue is considered in the sales price.

Binding interactions of 1‐naphthol with dissolved organic matter of Lake Biwa and treated sewage wastewater: The role of microbial fulvic acid

The binding interactions of 1-naphthol with effluent and whole natural dissolved organic matter (DOM) samples were analyzed by using a fluorescence quenching technique. Nonfractionated DOM samples from Lake Biwa (Japan), creek water, treated sewage effluents, and an extracted Lake Biwa fulvic acid (LBFA) standard were used as quenchers and compared at the same 1-naphthol with DOM organic carbon ratios found for low natural dissolved organic carbon (DOC) levels (∼4.5 mg/L). Natural and effluent DOM (eDOM) samples were characterized by the DOC level, relative hydrophobicity (RH%), ultraviolet (UV)-visible absorbance and fluorescence excitation emission spectroscopy. These parameters were compared with those of the reference LBFA standard. Concave-up Stern-Volmer plots accounted for both the partitioning and the adsorptive binding in the eDOM-polycyclic aromatic hydrocarbons (PAH) system as compared with the nonspecific partitioning in the natural DOM-PAH system. Strong linear regressions (r(2) > 0.80) between the log K(DOC) values, the RH%, the UV absorbances, and the Fl(340-435) -UV(340) indices for the structural composition and molecular weights of the DOM samples were obtained. These results suggest that low molecular weight microbial fulvic acid (<800 Da) is dominant in the eDOM-PAH binding interactions, as well as in the distinct molecular structure of the eDOM samples, which resulted in fivefold to sixfold higher binding magnitude for 1-naphthol than for the other samples.

Carbonyl reductase mRNA abundance and enzymatic activity as potential biomarkers of oxidative stress in marine fish

Carbonyl reductase (CBR) is an enzyme involved in protection from oxidative stress. In rainbow trout (Oncorhynchus mykiss), the hepatic mRNA abundance of the two isoforms (A and B) is increased after exposure to treated sewage effluents, as well as after exposure with β-naphthoflavone (β-NF) and the pro-oxidant paraquat. In this study, we show that the same chemicals similarly increase the single known hepatic CBR mRNA level and CBR catalytic activity in the coastal living eelpout (Zoarces viviparus). Hepatic CBR mRNA abundance and catalytic activity were also compared between eelpout collected at contaminated and reference sites on the Swedish west coast, but no differences were observed. In conclusion, CBR is a potential biomarker candidate for monitoring the exposure and effects of AhR agonists and/or pro-oxidants in the marine environment, but more research is needed to investigate temporal regulation as well as dose dependency for different chemicals. The mRNA and enzymatic assays presented in this study provide two additional tools for researchers interested in expanding their biomarker battery.

Assessment of anthropogenic influences on surface water quality in urban estuary, northern New Jersey: multivariate approach

Concentrations of selected heavy metals (Cd, Cr, Cu, Pb, Ni, Fe, and Zn), nutrients (NO (3) (-) and NH(3)), fecal coliform colonies, and other multiple physical-chemical parameters were measured seasonally from 12 locations in an urban New Jersey estuary between 1994 and 2008. Stepwise regression, principal component analysis, and cluster analysis were used to group water quality results and sampling locations, as well as to assess these data's relationship to sewage treatment effluents and the distance to the mouth of the river. The BOD(5), NH(3), NO (3) (-) and fecal coliform counts clustered as one group and positively correlated to the distances from treated effluent and the measures of magnitude at the discharge points. Dissolved solids and most metal species scored high along a single principal component axes and were significantly correlated with the proximity to the industrialized area. From these data, one can conclude that the effluent discharge has been a main source of anthropogenic input to the Hackensack River over the past 15years. Therefore, the greatest improvement to water quality would come from eliminating the few remaining combined sewer overflows and improving the removal of nutrients from treated effluents before they are discharged into the creeks and river.

Feasibility study on the application of advanced oxidation technologies for decentralised wastewater treatment

Abstract Advanced oxidation technologies (AOTs) have been widely investigated for their potential application in post-tertiary sewage treatment due to their ease of operation, high efficiency in organic mineralisation, inactivation of pathogens and low formation of disinfection by-products. This study aimed to evaluate the technical, economical and environmental feasibility for applying AOTs at decentralised wastewater treatment. A comprehensive process selection and assessment framework for the application of AOTs in decentralised wastewater systems for wastewater recycling and reuse purposes were developed in this study. Different AOTs were assessed for their suitability to retrofit as an advanced wastewater treatment option to a decentralised wastewater case study plant in South East Queensland, Australia to produce Class A+ recycled water. Among the different AOTs assessed, it was assessed that the H2O2/UV process was the best AOT treatment option, in terms of technical, economic and environmental benefits for treating sewage effluent from the decentralised wastewater system analysed in this case study. It is anticipated that additional data sets from different pilot or full scale AOT plants will allow the performance predictions of AOTs for a wide range of decentralised wastewater treatment applications. Through this study, it is anticipated that the potential future uptake of AOTs as an advanced treatment option will be enhanced, given the comprehensive and detailed technical, economic and environmental analysis presented in the paper.

Does ketoprofen or diclofenac pose the lowest risk to fish?

Ketoprofen and diclofenac are non-steroidal anti-inflammatory drugs (NSAIDs) often used for similar indications, and both are frequently found in surface waters. Diclofenac affects organ histology and gene expression in fish at around 1μg/L. Here, we exposed rainbow trout to ketoprofen (1, 10 and 100μg/L) to investigate if this alternative causes less risk for pharmacological responses in fish. The bioconcentration factor from water to fish blood plasma was <0.05 (4 for diclofenac based on previous studies). Ketoprofen only reached up to 0.6‰ of the human therapeutic plasma concentration, thus the probability of target-related effects was estimated to be fairly low. Accordingly, a comprehensive analysis of hepatic gene expression revealed no consistent responses. In some contrast, trout exposed to undiluted, treated sewage effluents bioconcentrated ketoprofen and other NSAIDs much more efficiently, according to a meta-analysis of recent studies. Neither of the setups is however an ideal representation of the field situation. If a controlled exposure system with a single chemical in pure water is a reasonable representation of the environment, then the use of ketoprofen is likely to pose a lower risk for wild fish than diclofenac, but if bioconcentration factors from effluent-exposed fish are applied, the risks may be more similar.

Modelling defined mixtures of environmental oestrogens found in domestic animal and sewage treatment effluents using an in vitro oestrogen‐mediated transcriptional activation assay (T47D‐KBluc)

There is growing concern of exposure of fish, wildlife and humans to water sources contaminated with oestrogens and the potential impact on reproductive health. Environmental oestrogens can come from various sources including concentrated animal feedlot operations (CAFO), municipal waste, agricultural and industrial effluents. US EPA's drinking water contaminant candidate list 3 (CCL3) includes several oestrogenic compounds. Although these contaminants are currently not subject to any proposed or promulgated national primary drinking water regulations, they are known or anticipated to occur in public water systems and may require future regulation under the Safe Drinking Water Act. Using an in vitro transcriptional activation assay, this study evaluated oestrogens from CCL3 both individually and as a seven oestrogen mixture (fixed ray design) over a broad range of concentrations, including environmentally relevant concentrations. Log EC(50) and Hillslope values for individual oestrogens were as follows: estrone, -11.92, 1.283; estradiol-17α, -9.61, 1.486; estradiol-17β, 11.77, 1.494; estriol, -11.14, 1.074; ethinyl estradiol-17α, -12.63, 1.562; Mestranol, -11.08, 0.809 and Equilin, -11.48, 0.946. In addition, mixtures that mirrored the primary oestrogens found in swine, poultry and dairy CAFO effluent (fixed-ratio ray design), and a ternary mixture (4 × 4 × 4 factorial design) of oestrogens found in hormone replacement therapy and/or oral contraceptives were tested. Mixtures were evaluated for additivity using both the concentration addition (CA) model and oestrogen equivalence (EEQ) model. For each of the mixture studies, a broad range of concentrations were tested, both above and below environmentally relevant concentrations. Results show that the observed data did not vary consistently from either the CA or EEQ predictions for any mixture. Therefore, either the CA or EEQ model should be useful predictors for modelling oestrogen mixtures.

Understanding effects of global change on water quantity and quality in river basins- The SCARCE Project

The increasing anthropogenic manipulation of the hydrological cycle, as well as the exacerbation of climate change forcing, result in resource pressures that translate in even larger uncertainties in sensitive geographical areas. In particular, the Mediterranean region is undergoing severe alterations in water availability because of a decrease in the number of precipitation days but also in an increase of heavy rain events. An imbalance between water availability and its use is obvious in these water-thirsty regions, and clearly impacts the sustainability of water resources. The consequences are multiple, and include direct impacts on economic sectors that use and depend upon water availability, such as agriculture, tourism or industry. Ultimately, however, these consequences are the basis for a conflict between natural ecosystems and human needs, where ecosystems are those most challenged and their services remain at risk. The effects of water scarcity on river basins extend from its associated hydrological irregularity to the chemical quality of available water systems. Higher nutrient and pollutant concentrations are expected under lower water flows, both as an effect of direct human inflows as well as a simple effect of lower water dilution. This is especially relevant in many arid and semi-arid river systems, where flowing waters under scarcity mostly consists of treated sewage effluents. Wastewaters are being reused for drinking purposes and agriculture; some chemical compounds may eventually be transported from the waste water treatment plants (WWTPs) to river waters, and affect the chemical and biological quality of those waters. In these situations, potential water quality problems extend to the higher concentration of emerging pollutants, presence of pathogenic organisms, and multiple effects on the biota dwelling within the river systems. Biological communities respond to harsher environmental conditions imposed by scarcity with lower diversity, arrival of invasive species, as well as with lower efficiency of biological processes, some involving water quality as a return. The increased pressure on water resources will cause additional effects on aquatic ecosystems, in which the stress being produced by scarcity may sum up others physical or chemical stressors. Groundwater quality may be also affected by farming, or after leakage of industrial and domestic pollutants, making the use of these resources much more tenuous. This special issue is a collection of key articles presented at the 1st Annual Conference of the SCARCE-CONSOLIDER Responsible editor: Philippe Garrigues

The development and application of a system for simultaneously determining anti-infectives and nasal decongestants using on-line solid-phase extraction and liquid chromatography–tandem mass spectrometry

A method for the simultaneous analysis of antibiotics, antiviral and nasal decongestants in treated sewage effluent and surface water has been developed and validated. The method uses on-line solid phase extraction (SPE) of injected high-volume samples in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method includes a range of antibiotics (Trimethoprim, Oxytetracycline, Ofloxacin, Norfloxacin, Ciprofloxacin, Azithromycin, Doxycycline, Sulfamethoxazole, Erythromycin and Clarithromycin), an antiviral (Oseltamivir) and nasal decongestants (Naphazoline, Oxymetazoline and Xylometazoline). The method's detection limits (MDLs) ranged from (0.2 ng L(-1)) to (3.1 ng L(-1)), based on a 1 mL extraction volume. Its intra-day precision was determined by performing nine runs with 200 ng L(-1) samples; the intra-day relative standard deviation (RSD) ranged from 1% to 19%. Inter-day precision was determined by analyzing samples in triplicate over the course of three days, yielding relative standard deviations ranging from <5% to <26%. The linearity (R(2)) for all compounds tested was >0.90. Spike relative recoveries ranged from 40% to 157% and 40% to 152% for STP effluent and surface water samples, respectively. Finally, the method was used to analyze real effluent and surface water.

Optimization of an integrated sponge – Granular activated carbon fluidized bed bioreactor as pretreatment to microfiltration in wastewater reuse

A specific integrated fluidized bed bioreactor (iFBBR) was optimized in terms of organic loading rate (OLR), hydraulic retention time (HRT) and frequency of new sustainable flocculant (NSBF) addition for primary treated sewage effluent (PTSE) treatment. It was observed that iFBBR achieved the best performance with the operating conditions of 4times/day NSBF addition, HRT of 90min and OLR of 8.64kgCOD/daym3. The removal efficiencies were found to be more than 93% of dissolved organic carbon (DOC), 61% of total nitrogen (T-N) and 60% of total phosphorus (T-P). iFBBR as pretreatment of submerged microfiltration (SMF) is successful in increasing the critical flux and reducing the membrane fouling. NSBF-iFBBR-SMF hybrid system led to very high organic removal efficiency with an average DOC removal of 97% from synthetic PTSE.

Effects of Sludge Concentrations and Different Sponge Configurations on the Performance of a Sponge-Submerged Membrane Bioreactor

The performance of a novel sponge-submerged membrane bioreactor (SSMBR) was evaluated to treat primary treated sewage effluent at three different activated sludge concentrations. Polyurethane sponge cubes with size of 1 × 1 × 1 cm were used as attached growth media in the bioreactor. The results indicated the successful removal of organic carbon and phosphorous with the efficiency higher than 98% at all conditions. Acclimatised sponge MBR showed about 5% better ammonia nitrogen removal at 5 and 10 g/L sludge concentration as compared to the new sponge system. The respiration test revealed that the specific oxygen uptake rate was around 1.0-3.5 mgO(2)/gVSS.h and likely more stable at 10 g/L sludge concentration. The sludge volume index of less than 100 mL/g during the operation indicated the good settling property of the sludge. The low mixed liquor suspended solid increase indicated that SSMBR could control the sludge production. This SSMBR was also successful in reducing membrane fouling with significant lower transmembrane pressure (e.g. only 0.5 kPa/day) compared to the conventional MBR system. Further study will be conducted to optimise other operating conditions.

Startup and operation of a large wastewater treatment plant in warm climate and under modified conditions – a case study

This study summarizes the findings and lessons learned from the start up and operation of a large wastewater treatment plant in warm climate under modified conditions. The treatment works comprise of a newly constructed sewage treatment plant located in the city of Dubai, U.A.E with an ultimate capacity of 300 Ml/d. The plant can be reviewed in three major parts; (i) liquid stream, (ii) sludge stream and (iii) odor control stream all having the latest state of the art technology and related equipments. The challenge in starting up the plant was related to the fact that only 20% of the flow was available in the form of hauled sewage to be hauled from septic tanks located in various parts of the city and also from the nearby industry which was uncontrollable. Furthermore, some parts of the plant were not ready to be commissioned on the day of the planned startup not to mention that effluent irrigation main was not complete to receive the treated sewage effluent (TSE) from the plant. A comprehensive commissioning plan was implemented and followed during the startup which was tailored according to the actual conditions. The plant commissioning was conducted in a phased sequence to cater for the expected and unexpected changes related to the inlet conditions. Commissioning and operation of the plant was carried for over 18 months with success considering the challenging and difficult conditions.

The effectiveness of sewage treatment processes to remove faecal pathogens and antibiotic residues

Pathogens and antibiotics enter the aquatic environment via sewage effluents and may pose a health risk to wild life and humans. The aim of this study was to determine the levels of faecal bacteria, and selected antibiotic residues in raw wastewater and treated sewage effluents from three different sewage treatment plants in the Western Cape, South Africa. Sewage treatment plant 1 and 2 use older technologies, while sewage treatment plant 3 has been upgraded and membrane technologies were incorporated in the treatment processes. Coliforms and Escherichia coli (E. coli) were used as bioindicators for faecal bacteria. A chromogenic test was used to screen for coliforms and E. coli. Fluoroquinolones and sulfamethoxazole are commonly used antibiotics and were selected to monitor the efficiency of sewage treatment processes for antibiotic removal. Enzyme Linked Immunosorbent Assays (ELISAs) were used to quantitate antibiotic residues in raw and treated sewage. Raw intake water at all treatment plants contained total coliforms and E. coli. High removal of E. coli by treatment processes was evident for treatment plant 2 and 3 only. Fluoroquinolones and sulfamethoxazole were detected in raw wastewater from all sewage treatment plants. Treatment processes at plant 1 did not reduce the fluoroquinolone concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced the fluoroquinolone concentration by 21% and 31%, respectively. Treatment processes at plant 1 did not reduce the sulfamethoxazole concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced sulfamethoxazole by 34% and 56%, respectively. This study showed that bacteria and antibiotic residues are still discharged into the environment. Further research needs to be undertaken to improve sewage treatment technologies, thereby producing a better quality treated sewage effluent.