Reuse Of Effluent Research Articles

AVALIAÇÃO DO POTENCIAL DE REUSO DE EFLUENTES DE ETE EM ÁREAS IRRIGADAS DA BACIA HIDROGRÁFICA PIANCÓ-PIRANHAS-AÇU COM VISTAS A UNIVERSALIZAÇÃO

A Bacia Hidrográfica Piancó-Piranhas-Açu (PPA) abrange uma área total de 43.683 km² (ANA, 2016), com baixas precipitações, resultando em secas hídricas. O reuso de efluentes pode ser visto como uma prática que combate e minimiza os impactos sofridos pelas secas severas. Assim, uma vez que a região possui baixo atendimento ao tratamento de esgoto, neste trabalho, foi realizada uma avaliação do futuro potencial de reuso de efluentes de ETEs em áreas irrigadas. Assim, observou-se que, em relação à projeção para implantação das ETEs, em 2035, serão 131 ETEs em operação, com uma vazão total de 1,41 m3/s. A demanda de água para a agricultura irrigada na bacia é de 17,48 m³/s e com isso a oferta da água de reuso pode representar 8% da demanda de água para irrigação, a um custo estimado de transporte variando entre R$ 2,46/m3 e R$ 12,62/m3, em função do estado (PB e RN) e das distâncias de transporte (10 a 50 km). Comparando o custo da água de reuso com o valor do consumo da água bruta, constatou-se que os valores médios praticados atualmente para consumo de água na irrigação (0,02 R$/m3) inviabilizam financeiramente a prática e não se alinham com os objetivos instituídos pela lei das águas, já que os valores cobrados são ínfimos. Por fim, ficou ainda mais evidente a necessidade em se atingir a universalização do esgotamento sanitário, não somente para minimizar a poluição dos corpos d’água, mas também em propiciar efluentes tratados para a prática de reuso.
 

A critical evaluation of comparative regulatory strategies for monitoring pharmaceuticals in recycled wastewater

Pharmaceuticals are a subset of micropollutants, present in the environment in trace concentrations. Because of their persistent nature, these chemicals are of particular concern. Little is known about how mixtures of pharmaceutical residues, found in WWTP effluents, affect the environment or public health. Yet, numerous studies show negative outcomes for both aquatic and terrestrial organisms, suggesting that they are given both to bioaccumulation and uptake in plants. Israel leads the world in effluent reuse (86%), almost exclusively utilized for purposes of agricultural irrigation. Pharmaceuticals, however, are not included in Israel's water regulatory oversight or management, essentially creating an epidemiological experiment among its citizens and environment. Globally, these compounds also are not commonly subject to monitoring or regulation. This study reviews and analyzes water policies and regulation worldwide that address the presence of pharmaceuticals in water resources, with a particular focus on Australia, Singapore, Switzerland, and the USA. Furthermore, the study investigates the reasons why these chemicals are not yet regulated in Israel. Based on a comprehensive evaluation of the data and analysis of the regulatory rationale in other countries, a list of recommended pharmaceutical standards that should be measured and monitored in Israel's wastewater treatment system is proposed. The suggested prioritization criteria should be at the heart of a new regulatory agenda for controlling pharmaceutical contamination in wastewater.

Combined Domestic and Hospital Wastewaters Treatment by Natural Lagoon System in Tropical Area, Korhogo, Ivory Coast

Wastewaters discharged into surface waters highly impacted humans and living aquatic organisms particularly when the treatment applied to reduce chemical and biological pollution is not appropriated. Biological treatment systems are often applied for the treatment of domestic wastewaters. These systems are limited when applied to the treatment of hospital wastewaters. In this study, we evaluated the efficiency of natural lagoon system, applied to treat combined wastewaters from hospital and from residences of nursing students. Results show that the lagoon system remove 98% of COD, 87% of BOD, 95% of TSS and 92% of total nitrogen. Arsenic and copper are removed (40%), but lead and cadmium concentrations increase in the effluent. Globally, the concentrations of nutrients and heavy metals, in the effluents, are inferiors to the limit values proposed by the Ivorian guidelines for water pollution. However, the reuse of effluents for irrigation of crops likely to be eaten uncooked is not recommended because of the high concentration of fecal bacteria (1.00 x 10⁵ CFU <i>E. coli.</i> 100 mL^-1. The disinfection process must be implemented after biological treatment to ensure the elimination of pathogenic microorganisms present in the effluent and sludge, before their reuse in agriculture.<div><br></div>

Potential Reuse of Treated Textile Effluent in Fly Ash Concrete

Abstract In a preliminary effort to deal with the present fresh water demand in the construction industry, this article examines the potential reuse of textile effluent as mixing water in making fly ash concrete. The effluents were collected from a textile industry at different stages of treatment, such as Collection Tank Effluent, Effluent after Anaerobic Treatment (EAT), Tertiary Treatment Effluent, and Reverse Osmosis Feed Effluent. The collected effluent samples have been analyzed to establish physicochemical characteristics and their effects on the properties of concrete, such as compressive strength, split tensile strength, and flexural strength. Higher salt content in effluent mix water significantly increased the final setting time of the binder. Furthermore, the workability of the concrete made with effluent mix water is relatively higher than that of the control concrete mix. Also, concrete mixes made with textile effluent mix water demonstrated greater strength than that of the control concrete. Furthermore, EAT mixes have exhibited maximum compressive strength compared with other mixes and also had superior durability compared with the control concrete mix. The higher strength can be attributed to the nucleation effect caused by the presence of a high concentration of total solids in the effluent. However, this concrete can be recommended for applications of plain cement concrete, such as pavements, industrial floors, and curbs/gutters.

Advanced treatment of urban wastewater by UV-C/free chlorine process: Micro-pollutants removal and effect of UV-C radiation on trihalomethanes formation

The effect of the UV-C/free chlorine (FC) process on the removal of contaminants of emerging concern (CECs) from real urban wastewater as well as the effect of UV-C radiation on the formation of trihalomethanes (THMs) compared to FC process alone was investigated. Unlike of FC process, UV-C/FC was really effective in the degradation of the target CECs (carbamazepine (CBZ), diclofenac, sulfamethoxazole and imidacloprid) in real wastewater (87% degradation of total CECs within 60 min, QUVC = 1.33 kJ L−1), being CBZ the most refractory one (49.5%, after 60 min). The UV-C radiation significantly affected the formation of THMs. THMs concentration (mainly chloroform) was lower in UV-C/FC process after 30 min treatment (<1 μgL−1 = limit of quantification (LOQ)) than in FC process in dark (2.3 μgL−1). Noteworthy, while in FC treated wastewater chloroform concentration increased after treatment, UV-C/FC process resulted in a significant decrease (residual concentrations below the LOQ), even after 24 h and 48 h post-treatment incubation. The formation of radicals due to UV-C/FC process can reduce THMs compared to chlorination process, because part of FC reacts with UV-C radiation to form radicals and it is no longer available to form THMs. These results are encouraging in terms of possible use of UV-C/FC process as advanced treatment of urban wastewater even for possible effluent reuse.

Case study on sustainability of textile wastewater treatment plant based on lifecycle assessment approach

Abstract The present study is aimed at the estimation of the environmental footprints of a textile effluent treatment plant in India based on Lifecycle analysis (LCA) thinking of gate-to-gate approach with closed-loop recycling. The real-time operational data were collected on a daily basis for a year with minimum experimental uncertainties and treated as lifecycle inventory. Based on existing plant practice, two-fold functional units of 1,500 m 3 (effluent stream 1) and 1,200 m 3 (effluent stream 2) were considered for the study, and the system boundary was designed. The analysis demonstrated that the ozonation process contributes significantly in generating environmental burden, with a global warming potential of 1,440 kg and 2,041 kg CO 2 equivalent for effluent stream 1 and 2, respectively. Conversely, activated carbon filter imparts less to the environmental burden, with a global warming potential of 217 kg and 173.5 kg CO 2 equivalent for effluent stream 1 and 2, respectively, compared to other processes. Based on the parametric analysis, it was understood that electricity contributed substantially; and thus sensitivity/scenario analysis was carried out, showing 50% and 90% attenuation of environmental burden with increased renewable energy share from 50% to 100%. Increase in effluent reuse scenario also found to have augmented the environmental performance of the system. Based on the data presented in this study, policy-makers can decide strategies to reduce the environmental burden of textile industry effluent.

Study on the reuse of anaerobic digestion effluent in lactic acid production

Abstract A novel process for reuse of anaerobic digestion effluent in lactic acid fermentation was investigated to resolve wastewater pollution in lactic acid industry. A series of experiments were performed and the results showed that anaerobic digestion effluent directly reused did not affect liquefaction of raw materials, but inhibited lactic acid fermentation instead. Further experimental studies proved that excess ammonia-nitrogen, Zn2+, Fe2+, S and Mn2+ in the anaerobic digestion effluent could inhibit lactic acid fermentation and their corresponding critical inhibition concentrations were 100 mg/L, 1 mg/L,1 mg/L, 2.5 mg/L and 1 mg/L, respectively. In this paper, the activated carbon treatment was adopted to process the anaerobic digestion effluent, and these inhibitors had been effectively removed. The removal rate of metal ions reached 75%, and that for ammonia-nitrogen was over 80%. Application of the treated anaerobic digestion effluent in lactic acid fermentation, there was 129.59 ± 3.13 g/L of lactic acid, which was comparable to the control (130.09 ± 2.12 g/L). This new process is of significance to the realization of no-waste manufacturing, energy saving and emission reduction in lactic acid industry. It can be concluded that a cleaner way to produce lactic acid is realized.

Combined system for the treatment and reuse of urban wastewater: the efficiency of anaerobic reactors + hybrid constructed wetlands + ozonation.

The research developed a combined system in batch flow and in pilot scale for the treatment and reuse of urban effluents. The system was fed raw effluent from a university campus in Brazil and composed of four anaerobic reactors, three constructed wetlands (CWs) and an ozonation unit. The three sequential hybrid constructed wetlands were composed of a floating treatment wetland, an aerobic-anoxic baffled constructed wetland (CW) and a saturated vertifcal flow CW. Later, during the last trimester, weekly samples of the treated effluent were ozonated by bubbling with an application rate of 240 mg.h-1 O3. The system presented high removal rates efficiencies in terms of carbonaceous organic matter (78.9%), nitrogen (91.0%), color (96.7%) and turbidity (99.1%). In addition, it worked well for disinfection and acute ecotoxicity, but P was only efficiently (75%) removed in the first 8 months, with removing efficiency declining after this period. Ozonation provided significant color removal and an increased pH. The combination of floating, alternated upflow and downflow and saturated vertical flows improved the treatment of wastewater. This was due to the presence of both aerobic and anaerobic zones, as well as the filter substrate, through an integrated system with simple construction and operation and increased lifespan.

Evaluation of the use of fertilizer obtained from pharmaceutical effluent

Sustainability encompasses several aspects, one of which is the reuse of nutrient-rich effluent. In recent years, improper disposal of pharmaceuticals and pharmaceutical effluent, which contain recalcitrant compounds, has caused great environmental damage. An alternative disposal strategy that has been studied for several residues is their reuse for agricultural purposes. This work evaluated the potential of using pharmaceutical effluent for fertilizing Schinus molle, a native Brazilian species locally known as “aroeira-salsa.” Effluent was pretreated by chemical precipitation, and the solid phase was tested as fertilizer. Seedlings were grown in soil or compost. The soil used was classified as Red-Yellow Acrisol with medium loamy texture and high Al content, which is typically found in the Vale do Paraíba region, São Paulo, Brazil. Two agricultural composts were used as substrate, both from the Taboão Ecological Park located in Vale do Paraíba. Fertilizer application improved the physicochemical characteristics of all growing media, increasing C, N, P, K, Mg, and Ca contents, base saturation, and pH, while decreasing Al content and density. Fertilization improved nutrient absorption and plant growth.

Capacity of Caulerpa lentillifera in the Removal of Fish Culture Effluent in a Recirculating Aquaculture System

Aquaculture is one of the fastest growing food producing industries in the world. Aquaculture effluent contains high concentrations of inorganic nutrients. Reduction of these inorganic nutrients in aquaculture effluent is crucial for fulfilling the effluent standards or reuse of aquaculture effluent. This study investigated the effective use of green macroalga Caulerpa lentillifera as a bioremediatory species for nutrient removal from aquaculture effluent by conducting an on-station experiment and measurements. The effluent of a fish culture unit was circulated through a macroalgal culture unit every four days for a total of 60 days, allowing 15 circulations. Concentrations of inorganic nutrients (NO2−-N, NO3−-N, NH3-N, and PO43−) were measured in the integrated system consisting of a fish unit, settling unit, macroalgal unit and extra tank for water circulation in triplicates. Multiple linear regression analysis revealed that the application of the bioremediation system led to a significant reduction in nutrient concentrations within one day, and slightly further in the following two days. On average over the 15 circulations, the first one day of application decreased the concentrations of NO2−-N, NO3−-N, NH3-N, and PO43− by 0.247 mg/L, 81.6 mg/L, 0.682 mg/L, and 0.352 mg/L, respectively. Furthermore, the C:N ratio of macroalgae decreased during the 60-day application period, providing evidence of the nutrient uptake by macroalgae. Based on the European Union (EU) standard and quality criteria of France and the Joint FAO/WHO Expert Committee (JFWEC), the macroalgae grown in the integrated system were at the safe level for human consumption in terms of contents of Cd, Pb, and As. The results of our study imply that recirculating aquaculture systems utilizing C. lentillifera for biofiltration have the potential for effective treatment of aquaculture effluent integrating fish and macroalgae production.

Toxicological Comparison of Water, Wastewaters, and Processed Wastewaters.

Drinking water utilities will increasingly rely on alternative water sources in the future, including wastewater reuse. Safety must be assured in the application of advanced oxidation processes (AOPs) and supporting treatments for wastewater effluent reuse. This study developed toxicological profiles for source and tap waters, wastewaters, and treated effluents by different processes from four military installation locations. The objective of this study was to evaluate the toxicity of extracted organics from diverse source waters and after reuse treatments. The toxicity analyses included thiol reactivity, mammalian cell cytotoxicity, and genotoxicity. Differences in toxicity between source or tap waters and effluents from wastewater treatment processes supported AOP treatment to reduce risks of potable reuse. An anoxic and aerobic activated sludge process followed by sand filtration controlled toxicity to levels similar to a municipal drinking water. An anaerobic membrane bioreactor process exceeded the toxicity levels of a typical drinking water. Two AOP processes (ultraviolet (UV) + reverse osmosis (RO) + chlorination (NaOCl) or RO + UV-H2O2 + NaOCl) significantly reduced toxicity. The integration of the wastewater systems with ultrafiltration, AOP, and RO was effective to reduce the toxicity to levels comparable to, or better than, tap water samples.

Effects of gamma irradiation on physicochemical and biological characteristics of wastewater effluent and sludge

The effluent and sludge samples collected at the Municipal Wastewater Treatment Plant of Southern Tehran were irradiated with doses of 5, 10 and 20 kGy using a 60Co gamma source and without irradiation (control) in a completely randomized design with three replications. In the term of total and fecal coliforms load, the gamma ray was more effective in the effluent disinfection than in the sludge. Approximately, three logs reduction in total and fecal coliforms were observed at the dose of 20 kGy in the sludge. The complete inactivation of the coliforms load in the effluent was achieved by 10 kGy gamma ray, whereas for sludge, it was not achieved even at 20 kGy. The improvement in the irradiated effluent quality was demonstrated by the significant reductions in chemical oxygen demand, biochemical oxygen demand, turbidity, pH, EC and concentrations of nitrate and phosphate. The other characteristics of the effluent and sludge did not change and/or changes did not show any trend as a result of treatments except concentrations of nitrogen and copper in the sludge and calcium and potassium in the effluent. The results proved that gamma ray can be applied as an effective technique for the reuse of effluent and sludge in agricultural soils.

Elimination efficiency of organic UV filters during ozonation and UV/H2O2 treatment of drinking water and wastewater effluent

The efficiency of elimination of organic UV filters by ozonation and UV254nm/H2O2 processes was assessed and predicted in simulated treatments of sewage-impaired drinking water and wastewater effluent in bench-scale experiments. Second-order rate constants (k) for the reactions of the eight UV filters with ozone and OH were determined by quantum chemical calculations and competition kinetics methods, respectively. The UV filters containing phenolic (ethylhexyl-salicylate, homosalate, and benzophenone-3) and olefinic moieties (4-methylbenzylidene-camphor, benzyl-cinnamate, and 2-ethylhexyl-4-methoxycinnamate) showed high ozone reactivity (k ≥ 8 × 104 M−1s−1 at pH 7), while those without such electron-rich moieties (isoamyl-benzoate and benzophenone) were ozone-refractory. All the UV filters showed high OH reactivity (k ≥ 6.2 × 109 M−1s−1). In concordance with the rate constant information, the phenolic and olefinic UV filters were efficiently eliminated by ozone treatment, requiring specific ozone doses of <0.5 mgO3/mgDOC for ∼100% elimination. The UV filters were eliminated by ≤ 38% at a UV fluence of 1500 mJ/cm2 in the UV254nm-only treatment. Rapid photoisomerisation between the E and Z geometric isomers was observed for the olefinic UV filter, benzyl-cinnamate. The addition of H2O2 (10 mg/L) greatly enhanced the elimination of all UV filters, indicating that OH was the main contributor to their elimination in the UV254nm/H2O2 treatment. A chemical kinetics approach developed previously for ozonation and UV/H2O2 processes was shown to predict the elimination of the UV filters in the tested water matrices reasonably well, demonstrating that the chemical kinetics method can be used for a priori prediction of micropollutant elimination in oxidative treatment processes for potable reuse of municipal wastewater effluents.

Environmental and economic performance evaluation of municipal wastewater treatment plants in India: a life cycle approach.

Life cycle assessment (LCA) was used to evaluate the environmental impacts associated with wastewater treatment plants (WWTPs). Moreover, an economic evaluation was also addressed using life cycle cost (LCC) approach. Emissions associated with electricity production for operating the WWTPs, emissions from the treated effluent and hazardous heavy metals emissions have been identified as the main contributors to the overall environmental impact. Among the WWTPs considered, soil biotechnology (SBT) obtained the lowest environmental impact in all the evaluated impact categories, except for eutrophication potential. While the aerated lagoons (AL) system presented the worst results due to the high electricity and chemicals consumption. Moreover, the results obtained from the evaluation of benefit from treated effluent reuse clearly indicate that there is a drop in the toxicity potential when the rate of effluent reuse is increased. On the other hand, the present worth of SBT was estimated to be Rs. 40 million/millions of litres per day (MLD) which is the highest as compared to other technologies. Membrane bioreactor (MBR) is the second highest (Rs. 24.7 million/MLD), which is mainly contributed by civil, electro-mechanical and membrane cost. The results of LCA and LCC provide specific insights about the factors which play a major role during the life cycle of wastewater treatment technology and its associated impacts.

Mitigation of organic fouling on ceramic membranes by selective removal of microbial-oriented organic matters in wastewater effluents

The fouling propensity of organic matter categorized by their origins has been investigated during the reuse of tertiary wastewater effluent by a ceramic ultrafiltration membrane with molecular weight cut-off (MWCO) around 1 kDa. Selective removal of organic matter was carried out with three carbon-based adsorbents including granular activated carbon (GAC), expanded graphite (EG), and multi-walled carbon nanotubes (MWNTs). Analysis on the residual organic matter after the adsorption revealed that EG and MWNTs mainly adsorbed microbial-oriented organic matters (MOOMs) such as the soluble microbial products (SMP)-like and aromatic protein (AP)-like organic compounds, while GAC showed non-selective organic removals. At the identical organic loading, feed solution treated by EG and MWNTs exhibited significantly lower fouling propensity than that of the GAC-treated sample. Consequently, the selective removal of MOOMs from tertiary effluents can provide an effective strategy to reduce organic fouling on ceramic membranes.

The Effect of Education Level on Accepting The Reuse of Treated Effluent in Irrigation

Gaza strip suffers from a serious shortage in water resources due to the continuous increase in population, life changes, political conditions and drought caused by climate change. Due to increased demand for water for domestic use, resulting accumulation of large quantities of wastewater in the treatment plant in Rafah. Therefore, reuse of treated wastewater is one of the most recently accepted approaches to save groundwater or domestic use. The aim of this research is to study the treated effluent quality from Rafah Treatment Plant, in addition to the effect of education level of the farmers on reusing treated wastewater for irrigation. A questionnaire was distributed to farmers to investigate the acceptance of using treated effluent for irrigation, meanwhile the effluent parameters tested were BOD, COD, TKN, NH4, NO3, P, Cd, Pb, and Cu accounted for 110, 250, 108, 127, 0.23, 17.9 mg/l, &lt; 0.003, &lt;0.001, and 19.9 µg/l. Most of reuse parameters were higher than the recommended levels for the effluent reuse based on the recommended Palestinian Standards for irrigation. About 80.7% of farmers accept using treated wastewater in irrigation and the Chi-square test analysis showed that, at P-value =0.00095 &lt; α= 0.05, there is a close relationship between the educational level of farmers and the acceptance of using of treated wastewater in irrigation, as long as it is safe and healthy.

Investigation and proposal for reuse of effluents from beneficiated bentonite products

AbstractThis work is intended to show the characterization of three effluents (X, Y, and Z) derived from laboratory analyses conducted in the quality control department of a beneficiated bentonite products factory in order to present alternatives for their treatment and final disposal according to Brazil's National Solid Waste Policy (Política Nacional de Resíduos Sólidos – PNRS, Law 12,305/2010, Brazil). Analyses to identify the characteristics of the effluents revealed that the pH, salinity, electroconductivity, and total dissolved solids were in agreement with the organic and mineral nature of the effluent constituents: solvent, clay minerals, water, and activating agent. To assess reuse proposals, the effluents were subjected to the following tests: (a) swelling characteristic with effluent X, (b) petrochemical characterization of Y, and (c) swelling characteristic using commercial solvent and activated clay produced with effluent Z. Preliminary results indicate that each of these effluents can be reused variously in the laboratory, as a fuel, or in the original analysis/process.

Comparison of Toxicity-Weighted Disinfection Byproduct Concentrations in Potable Reuse Waters and Conventional Drinking Waters as a New Approach to Assessing the Quality of Advanced Treatment Train Waters.

Advanced treatment trains based on oxidation, biofiltration, and/or granular activated carbon (Ox/BAF/GAC) are an attractive alternative to those based on microfiltration, reverse osmosis, and advanced oxidation (MF/RO/AOP) for the potable reuse of municipal wastewater effluents, but their effluent quality is difficult to validate with respect to chemical contaminants. This study evaluated the sum of the concentrations of 46 disinfection byproducts (DBPs) after treatment by chlorine or chloramines weighted by metrics of toxic potency in 10 full- or pilot-scale reuse trains to estimate the DBP-associated toxicity of their effluents. These total toxicity-weighted DBP concentrations were compared to those measured in their local, conventional drinking waters as a benchmark for water quality receiving regulatory and widespread public acceptance. The results indicated that while the DBP-associated quality of MF/RO/AOP-based reuse waters can readily exceed that of drinking waters, that of Ox/BAF/GAC-based reuse waters can approach or exceed that of drinking waters, particularly when they are chloraminated. Unregulated, halogenated DBPs were the dominant contributors to the estimated DBP-associated toxicity. While RO/AOP treatment preferentially reduced the concentrations of the more toxic brominated DBP species, BAC and GAC treatment favored brominated DBP species by removing DOC but not bromide. Comparing the total toxicity-weighted DBP concentration between reuse and drinking waters provides drinking water as a rational benchmark for water quality comparison, explicitly recognizes that contaminants occur as mixtures, provides utilities flexibility in selecting the most efficient treatment trains to reduce estimated toxicity, and can be expanded to encompass new contaminants as toxic potency data become available.

Adaptation of domestic effluent for agricultural reuse by biological, physical treatment and disinfection by ultraviolet radiation

Domestic effluent reuse is an alternative for irrigated agriculture in situations of reduced water availability. However, as there is the presence of pathogens in wastewater, the disinfection process is necessary before use. This research evaluated the sanitary and agricultural viability of treated wastewater at a pilot-scale station composed of a septic tank, Wetlands and an ultraviolet radiation (UV) disinfection system. The Sewage Treatment Station (STS) is installed in the Agricultural Sciences Center, UFSCar, in Araras city, SP, and receives 2000 L of sewage daily, which was monitored in terms of pH, turbidity, electrical conductivity (EC), dissolved oxygen (DO), sodium (Na), potassium (K), calcium (Ca), total nitrogen (TN), total phosphorus (TP), magnesium (Mg), total organic carbon (TOC), total coliforms (TC), Escherichia coli (E. coli) and Sodium Adsorption Ratio (SAR).The removal efficiency of the parameters was calculated based on the input and output means of each treatment unit. Results indicated removal efficiency for K (68.2%), TN (54.1%) and TP (36.1%). The levels of Na (26.7%) and Ca (22.9%) demonstrated the contribution of these salts to the wastewater; however, SAR did not present any risks for soil sodification. Microbiologically, the STS presented removal efficiency of 4 and 5 log-cycles for TC and E. coli, respectively. Therefore, results of monitoring indicate that the treated wastewater presents sanitary and agricultural viability, and conforms with the current legislation.

Evaluation of phytotoxicity of effluents from activated sludge and constructed wetland system for wastewater reuse.

The aim of this study was to evaluate the phytotoxicity of wastewater treated with horizontal subsurface flow (HSSF) constructed wetlands (CWs) and activated sludge (AS) system using disinfection treatment such chlorination and ultraviolet (UV) system. To assess the impact of the reuse of different effluents (HSSF-Cl, HSSF-UV, AS-Cl and AS-UV), bioassays using seeds of Raphanus sativus (R. sativus) and Triticum aestivum (T. aestivum), were performed on both Petri dishes and soil. Different treated wastewater concentrations were varied (6.25%, 12.5%, 25%, 50% and 100%) and the percentage of germination inhibition (PGI), percentage of epicotyl elongation (PEE) and germination index (GI) were determined. Positive effects (PGI and PEE <0% and GI >80%) of HSSF-Cl, HSSF-UV, AS-Cl and AS-UV effluents on germination and epicotyl elongation of R. sativus and T. aestivum were observed in Petri dishes bioassays. However, toxic effects of HSSF-Cl, HSSF-UV and AS-Cl on seeds germination and epicotyl elongation of both plant species were detected in soil samples (PGI and PEE >0% and GI <80%). Only R. sativus seeds to be irrigated with AS-UV achieved GI values above 86% for all concentrations evaluated. These results indicated that AS-UV effluent had a positive effect on seeds germination and can be recommended for treated wastewater reuse in agricultural irrigation.