Reclaimed wastewater use alternatives and quality standards

Reclaimed wastewater use is crucial for increasing water availability, improving water resources management, minimising environmental pollution and permitting sustainable nutrient recycling. However, wastewater also contains microbiological and chemical pollutants posing risks to human health and the environment, and these risks have to be handled. Successful use of reclaimed wastewater requires stringent standards for its treatment, disposal and distribution. This report summarises global and country-specific wastewater quality standards for different reclaimed wastewater use schemes, discusses specific standards and describes reclaimed wastewater use applications in two selected countries, Spain and Abu Dhabi Emirate. The World Health Organization (WHO) Guidelines for the Safe Use of Wastewater for Agriculture focus on the protection of public health. The European Commission does not directly regulate wastewater use, but discharge of treated wastewater into water bodies is regulated by Council Directive 91/271/EEC, which requires treated wastewater to have a maximum of 25 mg BOD5/L, 125 mg COD/L and 35-60 mg total solids (TS)/L. In sensitive areas, sewage treatment plant effluent must comply with a maximum of 2 mg total phosphorus/L and 15 mg total nitrogen/L. EU Council Directive 2008/105/EC also sets environmental quality standards for priority substances, i.e. pesticides, polycyclic aromatic hydrocarbons, phenolic compounds and volatile organic compounds. In Spain, the EU directives and Royal Decree 1620/2007 regulate use of reclaimed wastewater. The Royal Decree sets quality criteria for microbial parameters, solids and turbidity for different applications. The Regulation and Standards Bureau (RSB) of Abu Dhabi Emirate sets the quality criteria for water discharging to marine and land environments and used for irrigation. These include limits for organic matter, solids, nutrient, pathogen indicators and helminths. In Spain, agriculture is the largest sector for reclaimed wastewater use, consuming approx. 350 Mm3/year. Landscape irrigation and maintenance of natural hydrological regimes are the second largest users, consuming approx. 50-60 Mm3/year of wastewater each. In contrast, only <0.5% of the water used in industry is reclaimed wastewater. In Abu Dhabi Emirate, reclaimed wastewater is not used in crop cultivation, but most of the wastewater produced is used for irrigation of public parks and roadsides (287 Mm3/year) and in forestry (130 Mm3/year). District cooling in residential areas is another application for wastewater use in Abu Dhabi Emirate. The technologies used to facilitate wastewater treatment vary. The Barcelona metropolitan wastewater treatment plant (Spain), which supplies reclaimed wastewater for use, conducts biological treatment with activated sludge, tertiary treatment with coagulation-flocculation, filtration, UV disinfection, post-disinfection and oxygen saturation. The effluent wastewater complies with the Royal Decree and EU directives. In contrast, five treatment plants in the Navarra region of Spain use secondary treatment with trickling filters or activated sludge, two having lagoons for tertiary treatment. The hygiene quality of effluent from these plants does not comply with the Royal Decree and several fail to remove persistent organic compounds and pharmaceutical residues effectively. In Abu Dhabi Emirate, the largest sewage treatment plant, Mafraq, carries out conventional activated sludge treatment, followed by sand filtration and chlorination. Its effluent complies with RSB standards, but occurrence of pharmaceutical residues in effluent wastewater has been documented in Abu Dhabi. Besides standards and regulations and appropriate treatment, other aspects which need consideration in planning reclaimed wastewater use for various applications include: cultural and socio-economic aspects, willingness of users to accept and pay for treated wastewater, online and real-time water quality monitoring, and reduced energy use and waste generation

Open-air storage with and without composting as post-treatment methods to degrade pharmaceutical residues in anaerobically digested and dewatered sewage sludge

Over a period of 12 months, the fate of three hormones, 12 antibiotics and 30 pharmaceutically active substances (PhACs) was investigated during open-air storage without and with composting of anaerobically digested and dewatered sewage sludge. The effect of oxidation conditions during storage on degradation of hormones and PhACs in the sludge biomass was also examined. Under summer and winter conditions in Uppsala County, Sweden. two field-scale sludge windrows were constructed: open-air storage of sewage sludge windrow without composting (NO-COM)) and open-air storage windrow with composting (COM). NO-COM achieved effective removal of Sigma Hormones (85%) and Sigma Antibiotics (95%), but lower removal of Sigma PhACs (34%), during the study year. The top layers of the sludge pile had significantly lower concentrations of Sigma PhACs (3100-5100 ng/g ash) than deeper layers (8000-11,000 ng/g ash). After one year of composting, the degradation in the COM windrow resulted in concentrations of Sigma Hormones

Läkemedel och hormoner i avloppsslam under lagring, kompostering och ammoniakbehandling

Syftet med detta projekt var att öka kunskapen om hur utformningen av hanteringskedjan för återföring av slam till mark påverkar hur mycket läkemedel och hormoner som förs till marken vid spridning, antingen direkt via slamgödsling på åkermark, eller indirekt via tillverkning av anläggningsjord innehållande slamkompost. Projektets huvudhypotes var att ju bättre oxidationsförhållandena i slammet är ju bättre blir reduktionen av antibiotika, övriga läkemedel och hormoner. I projektet studerades redutionen av 12 antibiotika, 30 övriga läkemedel och 3 hormoner i 6 försöksled med initialt olika andel luftfyllda porer, och därmed olika förutsättningar för oxidation. De sex försöksleden, i ordning från stor initial andel luftfyllda porer till liten, var: MesPKom, slamkompost med mesofilt rötat poröst slam och krossat trädgårdsavfall; MesPÖpp, mesofilt rötat poröst slam som lagrades i öppen sträng; TermÖpp, termofilt rötat slam som lagrades i öppen sträng; MesKTäck, mesofilt rötat kompakt slam som lagrades i sträng täckt med ensilageplast; MesKÖpp, mesofilt rötat kompakt slam som lagrades i öppen sträng; och MesKTäckAm, mesofilt rötat via ureatillsats ammoniakbehandlat slam som lagrades i sträng täckt med ensilageplast. Dessutom studerades reduktionen i fem skikt olika djupt under ytan i MesPÖpp. De luftfyllda porer som fanns i de studerade slammen vid start av försöket försvann inom ett halvt år utom i slamkomposten MesPKom och de övre 40 centimetrarna på slamsträngarna. Resten av slammet i de olika försöksleden var anaerobt. Huvudhypotesen visade sig stämma. Reduktionen av antibiotika, övriga läkemedel ochhormoner var överlägset bäst i ledet med bäst oxidationsförhållanden, kompostledet, och bra till mycket bra i de övre, aeroba, skikten i djupstudien. Skillnaderna i reduktion av antibiotika, övriga läkemedel och hormoner mellan övriga försöksled, alla huvudsakligen anaeroba, kunde ej förklaras i detta projekt, förutom reduktionen av det naturliga hormonet östradiol vars reduktion hämmades om slammet rötats termofilt eller ammoniakbehandlats genom tillsats av urea. Under försöksåret blev reduktionen av antibiotika stor (>90 %), liksom av hormoner (>75%) oavsett om behandlingen var aerob eller anaerob. Reduktionen av såväl antibiotika som hormoner var bäst i de aeroba behandlingarna. Reduktionen av övriga läkemedel var måttligt (>50 %) i de övre aeroba skiktet på slamsträngen och mycket stor (95 %) i den aeroba, varma, storskaliga slamkomposten. I de anaeroba behandlingarna var reduktionen av övriga läkemedel i genomsnitt låg eller obefintlig. Den varierade mellan -33 %, alltså en ökning med en tredjedel, och en minsking med 34 % under försöksåret. I ett kopplat projekt jämfördes reduktionen av PFAS, ftalater och organofosfatestrar mellan slam som lagrades i öppen sträng i ett år (MesPÖpp) och slam som komposterades med krossat trädgårdsavfall (MesPKom) i ett halvt år. Resultaten visade på betydligt lägre halter av PFAS, ftalater och organofosfatestrar efter ett halvt års kompostering än efter ett års lagring i sträng

Efficiency of iron- and calcium-impregnated biochar in adsorbing phosphate from wastewater in onsite wastewater treatment systems

This study evaluated the potential of biochar impregnated with Fe3+ or Ca2+, or mixed with Polonite®, as a filter material for removal of phosphate (PO4-P) from wastewater in onsite wastewater treatment systems (OWTS). Four treatments with biochar were investigated: unimpregnated biochar (UBC), biochar impregnated with iron Fe3+ (FBC), biochar impregnated with calcium oxide (CBC), and biochar mixed with Polonite® (PBC). In a batch experiment using phosphate solution at concentrations 0.5, 3.3, 6.5, 13, and 26 mg PO4-P L–1, adsorption of PO4-P in the different treatments was modeled using Langmuir and Freundlich isotherms. Column filters (5 diameter × 55 cm height) packed with UBC, FBC, CBC, and PBC were then furnished with raw wastewater over 148 weeks. During this experiment, adsorption of PO4-P was investigated in response to increasing hydraulic loading rate (HLR; 56, 74, and 112 L m–2 day–1) and increasing phosphate loading rate (PLR; 195, 324, 653, and 1715 mg PO4-P m–2 day–1). Among the materials, FBC had the highest maximum adsorption capacity (Qm) based on Langmuir isotherms (3.21 ± 0.01 mg g–1). FBC and CBC showed robust performance with increasing HLR, while increasing PLR increased the amount of PO4-P retained in all filters. After 148 weeks of operation, removal of PO4-P (averaged over the last 18 weeks of operation) was 13 ± 16% for UBC, 40 ± 20% for CBC, 88 ± 12% for FBC, and 30 ± 18% for PBC. The PO4-P amount retained in filters over the 148 weeks was 84.75, 221.75, 358.38, and 152.36 g m–2 in UBC, CBC, FBC, and PBC, respectively. The adsorption capacity of the filters after 148 weeks was 1.50, 4.02, 6.41, and 2.75 mg g–1 for UBC, CBC, FBC, and PBC, respectively. The adsorption capacity values and breakthrough curves showed that low concentrations (i.e., &lt;2.6 mg L–1) of PO4-P in wastewater would allow the FBC filter to remain active for 58 months and the CBC filter for 15 months, before PO4-P removal declined to &lt;70%. In conclusion, biochar impregnated with iron and calcium is a promising solution for removal of PO4-P from wastewater in OWTS

Are There Too Many Lawyers--Introductory Remarks

The largest wastewater treatment plant in Jordan was monitored in the summer to determine the removal of pharmaceuticals and personal care products (PPCPs). Grab samples were collected from the influent and effluent of As-Samra Wastewater Treatment Plant (WWTP). Liquid chromatography and tandem mass spectrometry (LC–MS/MS) were utilized to determine the concentrations of 18 compounds of pharmaceuticals and personal care products (PPCPs). The results showed that 14 compounds were detected in the collected samples from the influent and effluent of As-Samra WWTP. These compounds are 1,7-dimethylxanthine, amphetamine, acetaminophen, caffeine, carbamazepine, cimetidine, cotinine, diphenhydramine, methylenedioxymethamphetamine (MDMA), morphine, phenazone, sulfamethazine, sulfamethoxazole, thiabendazole, and trimethoprim. However, four compounds were below the detection limit

How effective is the retention of microplastics in horizontal flow sand filters treating stormwater?

Microplastics accumulate in stormwater and can ultimately enter freshwater recipients, and pose a serious risk to aquatic life. This study investigated the effectiveness of lab-scale horizontal flow sand filters of differing lengths (25, 50 and 100 cm) in retaining four types of thermoplastic microplastics commonly occurring in stormwater runoff (polyamide, polyethylene, polypropylene, and polyethylene terephthalate). Despite the differences in particle shape, size and density, the study revealed that more than 98% of the spiked microplastics were retained in all filters, with a slightly increased removal with increased filter length. At a flow rate of 1 mL/min and after one week of operation, 62–84% of the added microplastics agglomerated in the first 2 cm of the filters. The agglomerated microplastics included 96% of high-density fibers. Larger-sized particles were retained in the sand media, while microplastics smaller than 50 μm were more often detected in the effluent. Microplastics were quantified and identified using imaging based micro Fourier Transform Infrared Spectroscopy. The efficient retention of microplastics in low-flow horizontal sand filters, demonstrated by the results, highlights their potential importance for stormwater management. This retention is facilitated by various factors, including microplastic agglomeration, particle sedimentation of heavy fibers and favorable particle-to-media size ratios.</p

Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries - case studies from Cochabamba, Bolivia

Wastewater irrigation is a common practice in developing countries due to water scarcity and increasing demand for food production. However, there are health risks and ecological risks associated with this practice. Small-scale wastewater treatment plants (WWTPs) intend to decrease these risks but still face management challenges. This study assessed how the management status of five small-scale WWTPs in Cochabamba, Bolivia affects health risks associated with consumption of lettuce and ecological risks due to the accumulation of nutrients in the soil for lettuce and maize crops. Risk simulations for three wastewater irrigation scenarios were: raw wastewater, actual effluent and expected effluent. Results showed that weak O&M practices can increase risk outcomes to higher levels than irrigating with raw wastewater. Improving O&M to achieve optimal functioning of small-scale WWTPs can reduce human health risks and ecological risks up to 2 log(10) DALY person(-1) year(-1) and to 2 log(10) kg nitrogen ha(-1) accumulated in soil, respectively

Pharmaceuticals in source separated sanitation systems: Fecal sludge and blackwater treatment

This study investigated, for the first time, the occurrence and fate of 29 multiple-class pharmaceuticals (PhACs) in two source separated sanitation systems based on: (i) batch experiments for the anaerobic digestion (AD) of fecal sludge under mesophilic (37 `C) and thermophilic (52 "C) conditions, and (ii) a full-scale blackwater treatment plant using wet composting and sanitation with urea addition. Results revealed high concentrations of PhACs in raw fecal sludge and blackwater samples, with concentrations up to hundreds of pg L-1 and fig kg-1 dry weight (dw) in liquid and solid fractions, respectively. For mesophilic and thermophilic treatments in the batch experiments, average PhACs removal rates of 31% and 45%, respectively, were observed. The average removal efficiency was slightly better for the full-scale blackwater treatment, with 49% average removal, and few compounds, such as atenolol, valsartan and hydrochlorothiazide, showed almost complete degradation. In the AD treatments, no significant differences were observed between mesophilic and thermophilic conditions. For the full-scale blackwater treatment, the aerobic wet composting step proved to be the most efficient in PhACs reduction, while urea addition had an almost negligible effect for most PhACs, except for citalopram, venlafaxine, oxazepam, valsartan and atorvastatin, for which minor reductions (on average 25%) were observed. Even though both treatment systems reduced initial PhACs loads considerably, significant PhAC concentrations remained in the treated effluents, indicating that fecal sludge and blackwater fertilizations could be a relevant vector for dissemination of PhACs into agricultural fields and thus the environment. (C) 2019 Elsevier B.V. All rights reserved

Bark and charcoal filters for greywater treatment

Water scarcity, inappropriate sanitation and wastewater pollution are critically important global issues. Greywater is a sustainable water source for recycling, so this thesis examined simple, robust, low-cost alternatives for on-site treatment of greywater to irrigation water quality. Laboratory-scale pine bark, activated charcoal and sand filters were evaluated as regards their pollutant removal and interactions between medium properties, greywater, microbial activity and bacterial community structure. The effects of hydraulic and organic loading rates (HLR and OLR) were described by general regression models (GRM). The quality of the treated greywater was evaluated against Jordanian standards for irrigation water. A series of experiments examined treatment of artificial greywater in terms of lowering biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphorus (Tot-P), nitrogen (Tot-N) and pathogen indicators (total thermotolerant coliforms) and tracer microorganisms (enterohaemorrhagic Escherichia coli (EHEC) and bacteriophage PhiX). Following greywater loading, all filter materials developed biofilms with high bacterial diversity and richness. The driving force shaping bacterial communities in bark material was its organic composition and low pH, while the communities in the charcoal and sand filters were more influenced by the greywater. The GRM indicated that the performance of all filters was influenced by the HLR and OLR of the present and previous runs. The organic matter content and surface and hydraulic properties of the bark filters resulted in high BOD5 removal rates (94-99%), even at increased HLR and OLR, but accompanied by release of dissolved organic substances originating from the bark itself. High nitrification occurred in the bark filters in all loading regimes tested, but with low Tot-N removal. The bark filters demonstrated 1-3 log10 removal of microorganisms, but bark organic nature made its filters more vulnerable to biodegradation and disintegration. The charcoal had large specific surface area, which provided the capacity for intermediate-high removal of BOD5 (83-97%), Tot-N (50-98%) and Tot-P (64-98%), but removal of microorganisms was poor. The sand filters demonstrated low BOD5 removal (67-91%) and high nitrification, but low nitrogen removal. Greywater treatment by bark and charcoal filters reduced their organics content to acceptable irrigation levels. Nitrogen and microorganisms must be further reduced to meet Jordanian standards on treated wastewater for irrigation