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Soil aquifer treatment (SAT) is a managed aquifer recharge technology that involves the utilization of treated wastewater as a source. Widely implemented in countries like Australia, Israel, and Spain, SAT offers technical (flexibility), economic (lower investment cost), and environmental (lower energy consumption) advantages that invite people in other countries to assess its potential. There have been numerous research studies and experiments conducted on the process level of SAT, focusing on how to eliminate pollutants and improve water quality. However, research at the system level is limited, which hampers its widespread application, especially in developing countries. In this paper, I provide a comprehensive guideline that highlights important factors to consider when implementing SAT as a technology. Proper site selection and careful planning steps, including pretreatment, hydrogeological factors, and economic calculations, can significantly improve the performance of an SAT system. The regulatory component acts as a barrier to the expansion of SAT facilities worldwide due to the lack of harmonization in regulations. This study includes the details and results of an examination of the legal framework and establishes comparative guidelines and water quality parameters that must be met by SAT projects utilizing reclaimed water. The maintenance and monitoring of the SAT system are also essential to anticipating and addressing potential issues such as clogging. Lastly, the social aspect, which is of utmost importance, should be carefully considered. It is advisable to ensure transparent communication with end users from the early stages of the project. These key elements are interconnected, and none should be considered less significant than the others. [ABSTRACT FROM AUTHOR]

Manganese (Mn2+) and cobalt (Co2+) metals have been reported to exhibit complex interactions with phosphate (PO43-) ions, which can influence their mobility, reactivity, and removal behavior in soil aquifer treatment system (SAT). This study aimed to investigate the role of manganese (Mn2+) and cobalt (Co2+) in phosphate (PO43-) removal within a soil aquifer treatment system. A lab-scale column experiment was conducted using sand as the filtration media, and a synthetic wastewater containing 20 mg/L PO43-, 60 mg/L Mn2+, and 40 mg/L Co2+ was used. The breakthrough curves showed efficient removal of PO43- during the infiltration process, with concentrations reaching as low as 1 mg/L. The regression analysis revealed that Mn2+ had a strong negative correlation effect on PO43- concentration, indicating its stimulatory role in PO43- removal. Conversely, Co2+ showed a strong positive correlation effect, suggesting its promoting effect on PO43- concentration. Optimization analysis identified optimal concentrations of 57.4 mg/L for Mn2+ and 4.8 mg/L for Co2+ that interacted with lower PO43- concentrations, achieving the desired outcome of reducing PO43- levels. These findings highlight the importance of considering Mn2+ and Co2+ concentrations in soil aquifer treatment systems for effective phosphate removal. [ABSTRACT FROM AUTHOR]

Autochthonous carbon fixation by algae and subsequent deposition of particulate organic matter can have significant effects on redox conditions and elimination of trace organic chemicals (TOrCs) in managed aquifer recharge (MAR). This study investigated the impacts of different algae loadings (0–160 g/m2) and infiltration rates (0.06–0.37 m/d) on overall oxygen consumption and elimination of selected TOrCs (diclofenac, formylaminoantipyrine, gabapentin, and sulfamethoxazole) in adapted laboratory sand columns. An infiltration rate of 0.37 m/d in conjunction with an algae load of 80 g/m2 (dry weight) sustained oxic conditions in the sand bed and did not affect the degradation of TOrCs. Thus, the availability of easily degradable organic carbon from algae did not influence the removal of TOrCs at an influent concentration of 1 µg/L. In contrast, a lower infiltration rate of 0.20 m/d in combination with a higher algae loading of 160 g/m2 caused anoxic conditions for 30 days and significantly impeded the degradation of formylaminoantipyrine, gabapentin, sulfamethoxazole, and diclofenac. Especially the elimination of gabapentin did not fully recover within 130 days after pulsed algae deposition. Hence, measures like micro-sieving or nutrient control are required at bank filtration or soil aquifer treatment sites with low infiltration rates. [ABSTRACT FROM AUTHOR]

A quantitative microbial risk assessment was conducted to assess the health risks associated with the exposure of agricultural workers to tertiary treated wastewater in irrigated fields through soil ingestion in Cyprus. Three pathogenic microorganisms were chosen, particularly E. coli (bacteria), rotavirus (viruses) and Cryptosporidium. Two extreme exposure scenarios were investigated. Monte Carlo simulations were performed using input data from literature, and the model outputs were compared to the health standards of the World Health Organization (WHO). The results suggested that additional treatment is required for all pathogens to satisfy the health standards. Sensitivity analysis identified the source concentration and pathogen reduction due to soil aquifer passage as the most influential factors in the model outputs. Additional computations were performed to evaluate the minimum pathogen reduction due to soil aquifer passage so that the health targets are achieved for the 95 % of the output values. Rotavirus and Cryptosporidium were found to require more treatment than E. coli. The inclusion of these reference pathogens to the monitoring network of the local authorities is recommended, and the role of soil aquifer passage is emphasized on reducing the concentration of the contaminants. [ABSTRACT FROM AUTHOR]

In order to select efficient media and find the optimum operation conditions for contaminant removal in soil aquifer treatment (SAT), column experiments with three different media were carried out under two different dry-wet ratio conditions. Phreeqc and Hydrus-1D were used to simulate the hydrogeochemical interactions. The results based on dissolution kinetics and cation exchange showed that the water-rock interaction in the columns led to the increase of Ca2+ and decrease of K+ in reclaimed water. The transfers of Ca2+ by cation exchange and calcite dissolution were 0.16–0.24 mmol/L and 0.13–0.22 mmol/L, respectively. The adsorption distribution coefficients (Kd) of NH4-N in columns ranged from 0.02 to 4 cm3/g. Higher Kd values were obtained in the columns of finer particle size or with the addition of biochar. The nitrification rates of NH4-N ranged from 0.08 to 0.4 day−1, but the denitrification rates of NO3-N were low (0–0.005 day−1). This indicated that NO3-N removal in the columns was insignificant. The increase of the drying period from 1 to 3 days promoted the microbial-mediated nitrification that transforms NH4-N to NO3-N. Our results indicated that the sand with a 15-cm biochar layer on the top reduced saturated hydraulic conductivity and was suitable for NH4-N removal. A low dry-wet ratio (i.e., 2:2 days) could be selected to prevent the transformation of NH4-N to NO3-N. The findings are helpful to assess hydrochemical characteristic change in SAT and provide a basis for the selection of a reasonable dry-wet ratio. Highlights: Hydrogeochemical processes were studied by 2-m column experiments and modeling. Dissolution kinetics of minerals was considered in reclaimed water chemical change. Cation exchange and dissolution/precipitation were quantified by inverse modeling. Water flux simulation showed that biochar reduced saturated hydraulic conductivity. Biochar addition significantly enhanced NH4+ removal in soil aquifer treatment. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT), as a gravity-based wastewater reuse process, is limited by oxygen availability to the microbial community in the soil. Using oxygen from enzymatic degradation of H2O2 to generate hyper-oxygen conditions can exceed solubility limitations associated with aeration, but little is known about the effect of hyper-oxygen conditions on the microbial community and the dominant bio-reactions. This study examined the impact of H2O2 addition on the community structure and process performance, along with SAT depth. Overall, two soil columns were incrementally fed synthetic secondary effluents to simulate infiltration through SAT. The experimental column received 14 mg/L hydrogen peroxide to double the level of natural oxygen available. The microbial kinetics of nitrifiers and heterotrophs were evaluated. We found that all of the H2O2 was degraded within the top 10 cm of the column, accompanied by a higher removal of COD (23 ± 0.25%) and ammonia (31 ± 3%) in comparison to the reference column. Higher nitrogen removal (23 ± 0.04%) was obtained for the whole process using H2O2. Analysis of nitrifiers indicated that ammonia-oxidizing bacteria were most influenced, obtaining higher concentration and abundance when exposed to H2O2. DNA sequencing analysis of samples exposed to H2O2 revealed significant community structure and diversity differences among heterotrophs. This study shows that not only aerobic, but also anoxic, microbial activity and process performance in a SAT system could be accelerated in existing infrastructure with H2O2, which could significantly decrease the associated environmental footprint. [ABSTRACT FROM AUTHOR]

Water percolation through infiltration ponds is creating significant synergies for the broad adoption of water reuse as an additional non-conventional water supply. Despite the apparent simplicity of the soil aquifer treatment (SAT) approaches, the complexity of site-specific hydrogeological conditions and the processes occurring at various scales require an exhaustive understanding of the system's response. The non-saturated zone and underlying aquifers cannot be considered as a black box, nor accept its characterization from few boreholes not well distributed over the area to be investigated. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological heterogeneities that has demonstrated useful to provide the detailed subsurface information required for groundwater modeling. The relationships between the electrical resistivity of the alluvial sediments and the bedrock and the difference in salinity of groundwater highlight the potential of geophysical methods over other more costly subsurface exploration techniques. The results of our research show that ERT coupled with implicit modeling tools provides information that can significantly help to identify aquifer geometry and characterize the saltwater intrusion of shallow alluvial aquifers. The proposed approaches could improve the reliability of groundwater models and the commitment of stakeholders to the benefits of SAT procedures. [ABSTRACT FROM AUTHOR]

Abstract Soil columns simulating soil aquifer treatment (SAT), fed with synthetic secondary effluent by intermittent infiltration of flooding/drying cycles, were characterized for nitrogen and organic carbon removal, and microbial ecology and biokinetics. The columns differed in the concentration ratio of chemical oxygen demand (COD) to the summed NH 4 +, NO 2 − and organic nitrogen—2 (C/N2) or 5 (C/N5). Chemical profiles along the column demonstrated a preference for COD oxidation over nitrification and coupled denitrification, with higher nitrogen loss (57% vs. 16%) in the C/N5 column. Unexpectedly, significant dominance of the genus Nitrospira over the genus Nitrobacter and ammonia-oxidizing bacteria (AOB) was strongly correlated at column depths where NH 4 + removal occurred. Moreover, the Nitrospira profile had the strongest correlation to the profile of NH 4 + (positive) and NO 3 − (negative), strongly indicating complete ammonia oxidation. 16S sequencing analysis of the topsoil in C/N2 vs. C/N5 columns revealed double the abundance of microbial aerobic potential (64% vs. 32%) vs. one-third the denitrification potential (13% vs. 31%). The concentrations and degradability levels of organic carbon were the most influential parameters shaping community structure. Niche differentiation within the biofilm attached to the soil is suggested to have an important role in the process's anoxic activity and nitrogen removal. Graphical abstract Image 1 Highlights • Higher C/N ratio in the feed resulted in significantly higher N loss. • The genus Nitrospira showed preponderance over the genus Nitrobacter and AOB. • Nitrospira correlated to ammonia removal show complete ammonia oxidation activity. • At top high C/N column microbial community reflected potential for denitrification. • Niche differentiation within the biofilm is significant in anoxic activity at SAT. [ABSTRACT FROM AUTHOR]

Abstract Two column pairs filled with 3.05-m of a sandy soil from the Upper San Gabriel Valley were operated for a period of four and ½ years on municipal effluent from the San Jose Creek Water Reclamation Plant operated by the Sanitation Districts of Los Angeles County (LACSD). One column pair was fed filtered, chlorinated effluent (tertiary effluent) for the entire period. The other pair was fed ozonated secondary effluent for 8-mo, ozonated secondary effluent filtered through biological activated carbon (O 3 /BAC) for 7-mo and tertiary effluent for 38-mo. Each column pair was operated in series, where the first column was operated for a shorter residence time and the second column for a longer residence time. Residence times tested were 5-d, 28-d, 30-d, 58-d, 60-d, 150-d and 180-d. For the last 38-mo, both pairs of columns had a residence time of 30-d in the first column and the total residence time of the two pairs was 150 and 180-d, respectively. Testing showed both of these pairs had the same long-term performance. The column pairs with a 150 to 180-d residence time, which were both fed tertiary effluent, reached an effluent total organic carbon (TOC) of 1.8 mg/L. Column pairs with a 28 to 30-d residence time, which were fed tertiary, ozonated, and O 3 /BAC effluent, reached effluent TOCs of 2.3, 2.1 and 1.8 mg/L respectively. In the latter, some TOC removal was shifted from the soil columns to the BAC. During the last 38 months of testing, using tertiary effluent as the source water, a series of sampling events was performed throughout the soil column system for N -nitrosodimethylamine (NDMA) and chemicals of emerging concern (CECs). NDMA was substantially reduced in all the columns, with a median value of 3 ng/L after 30-d and <2 ng/L after both 150 and 180-d. Twenty-one CECs were found in the majority of tertiary effluent samples, twelve of which were attenuated by the soil columns and the remaining were not. Chemicals found to be recalcitrant were 4-nonylphenol, acesulfame-k, carbamazepine, lidocaine, primidone, simazine, sucralose, sulfamethoxazole, and TCEP. Using excitation-emission matrix (EEM) techniques, soluble microbial products (SMP) peak characteristic of effluent organic matter (EfOM) is nearly eliminated after a 30-d hydraulic retention time (HRT) and completely eliminated in the 150/180-d samples. The intensity of the other peaks is significantly reduced as well, resulting in an EEM much like that of natural groundwater. Graphical abstract Image 1 Highlights • Soil columns fed tertiary effluent reduced the TOC 67% with a 150-day HRT. • NDMA was attenuated through soil columns by more than 99%. • Soil column treatment attenuated 12 of the 21 CECs found in tertiary effluent. • Soil columns were operated over four and ½ year period with tertiary effluent. [ABSTRACT FROM AUTHOR]

The long term behavior of total nitrogen and its components was investigated in a soil aquifer treatment system of the Dan Region Reclamation Project (Shafdan), Tel-Aviv, Israel. Use is made of the previous 40 years' secondary data for the main nitrogen components (ammonium, nitrate and organic nitrogen) in recharged effluent and observation wells located inside an infiltration basin. The wells were drilled to 106 and 67 m, both in a similar position within the basin. The transport characteristics of each nitrogen component were evaluated based on chloride travel-time, calculated by a cross-correlation between its concentration in the recharge effluent and the observation wells. Changes in the source of recharge effluent, wastewater treatment technology and recharge regime were found to be the main factors affecting turnover in total nitrogen and its components. During aerobic operation of the infiltration basins, most organic nitrogen and ammonium will be converted to nitrate. Total nitrogen removal in the upper part of the aquifer was found to be 47–63% by denitrification and absorption, and overall removal, including the lower part of the aquifer, was 49–83%. To maintain the aerobic operation of the infiltration fields, the total nitrogen load should remain below 10 mg/L. Above this limit, ammonium and organic nitrogen will be displaced into the aquifer. [ABSTRACT FROM AUTHOR]

Artificial recharge is used to increase the availability of groundwater storage and reduce saltwater intrusion in coastal aquifers, where pumping and droughts have severely impaired groundwater quality. The implementation of optimal recharge methods requires knowledge of physical, chemical, and biological phenomena involving water and wastewater filtration in the subsoil, together with engineering aspects related to plant design and maintenance operations. This study uses a novel Decision Support System (DSS), which includes soil aquifer treatment (SAT) evaluation, to design an artificial recharge plant. The DSS helps users make strategic decisions on selecting the most appropriate recharge methods and water treatment technologies at specific sites. This will enable the recovery of safe water using managed aquifer recharge (MAR) practices, and result in reduced recharge costs. The DSS was built using an artificial intelligence technique and knowledge-based technology, related to both quantitative and qualitative aspects of water supply for artificial recharge. The DSS software was implemented using rules based on the cumulative experience of wastewater treatment plant engineers and groundwater modeling. Appropriate model flow simulations were performed in porous and fractured coastal aquifers to evaluate the suitability of this technique for enhancing the integrated water resources management approach. Results obtained from the AQUASTRESS integrated project and DRINKADRIA IPA CBC suggest the most effective strategies for wastewater treatments prior to recharge at specific sites. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) is a managed aquifer recharge system in which the quality of the feed water (stormwater or wastewater treatment plant effluent) is further improved during soil passage. This paper provides an overview of SAT systems for wastewater treatment and reuse, and summarises design, removal efficiencies and pre-and post-treatment options as well as cost aspects of SAT using infiltration basins. SAT is an environment-friendly and robust multi-contaminant removal system which is effective in removing pathogens, nitrogen, bulk organic matter and the majority of organic micropollutants. The contaminant removal efficiency of SAT system, however, depends on several factors including source water quality, local hydrogeological conditions and process conditions applied. The performance of SAT system can be further improved by proper site selection and appropriate design of its components including pre- and post-treatment. SAT serves as an environmental and psychological barrier for water reuse applications. It is equally attractive for developed as well as developing countries and flexible enough to allow adaptation to local requirements by combining it with conventional (above the ground) natural or engineered water and wastewater treatment technologies. [ABSTRACT FROM AUTHOR]

Infiltration techniques for managed aquifer recharge (MAR), such as soil aquifer treatment (SAT) can facilitate low-cost water recycling and supplement groundwater resources. However there are still challenges in sustaining adequate infiltration rates in the presence of lower permeability sediments, especially when wastewater containing suspended solids and nutrients is used to recharge the aquifer. To gain a better insight into reductions in infiltration rates during MAR, a field investigation was carried out via soil aquifer treatment (SAT) using recharge basins located within a mixture of fine and coarse grained riverine deposits in Alice Springs, Northern Territory, Australia. A total of 2.6 Mm3 was delivered via five SAT basins over six years; this evaluation focused on three years of operation (2011-2014), recharging 1.5 Mm3 treated wastewater via an expanded recharge area of approximately 38,400 m2. Average infiltration rates per basin varied from 0.1 to 1 m/day due to heterogeneous soil characteristics and variability in recharge water quality. A treatment upgrade to include sand filtration and UV disinfection (in 2013) prior to recharge improved the average infiltration rate per basin by 40% to 100%. [ABSTRACT FROM AUTHOR]

Erythromycin (ERY), a widely used antibiotic, has recently been detected in municipal secondary effluents and poses serious threats to human health during wastewater reusing. In this study, the removal, fate, and degradation pathway of ERY in secondary effluent during soil aquifer treatment was evaluated via laboratory-scale SAT tests. Up to a 92.9% reduction of ERY in synthetic secondary effluent was observed in 1.0 m depth column system, which decreased to 64.7% when recharged with wastewater treatment plant secondary effluent. XRD-fractionation results demonstrated that the transphilic acid and hydrophobic acid fractions in secondary effluent compete for the adsorption sites of the packed soil and lead to a declined ERY removal. Moreover, aerobic biodegradation was the predominant role for ERY removal, contributing more than 60% reduction of ERY when recharged with synthetic secondary effluent. Destruction of 14-member macrocyclic lactone ring and breakdown of two cyclic sugars ( l -cladinose and d -desosamine) were main removal pathways for ERY degradation, and produced six new intermediates. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) systems rely on extensive physical and biogeochemical processes in the vadose zone and aquifer for water quality improvement. In this study, the distribution, quantitative changes, as well as the speciation characteristics of heavy metals in different depth of soils of a two-year operated lab-scale SAT was explored. A majority of the heavy metals in the recharged secondary effluent were efficiently trapped by the steady-state operated SAT (removal efficiency ranged from 74.7% to 98.2%). Thus, significant accumulations of 31.7% for Cd, 15.9% for Cu, 15.3% for Zn and 8.6% for Cr were observed for the top soil after 730 d operation, leading to the concentration (in μg g −1 ) of those four heavy metals of the packed soil increased from 0.51, 46.7, 61.0 and 35.7 to 0.66, 54.2, 70.4 and 38.8, respectively. By contrast, the accumulation of Mn and Pb were quite low. The residual species were the predominant fraction of the six heavy metals (ranged for 59.8–82.4%), followed by oxidisable species. Although the Zn, Cr, Cd, Cu and Mn were efficiently bounded onto the oxide components within the soil, the percentage of the labile metal fractions (water-, acid-exchangeable and reducible metal fractions) exhibited a slight increasing after 2 Y operation. Significantly heavy metals accumulation and slightly decreasing of the proportion of the stable fractions indicated a potentially higher environmental hazard for those six heavy metals after long-term SAT operation (especially for Cu, Zn and Cd). Finally, a linear relationship between the accumulation rate of metal species and the variation of soil organic carbon concentration and water extractable organic carbon was demonstrated. [ABSTRACT FROM AUTHOR]

With constrained Nile water and the cruel drop in per capita freshwater share in Egypt, soil aquifer treatment (SAT) appears an attractive, low-cost, unconventional water resource that is environmentally friendly and relatively easy to operate. Nevertheless, organic micropollutants (OMPs) in treated wastewater pose environmental and health risks if not properly attenuated through vadose zone infiltration. Thus, determination of OMP removal in a SAT system is important for sustainable groundwater management. In this study, a new, simple equation for the prediction of organic micropollutant removal in SAT systems was developed using gene expression programming (GEP). A wide range of 15 OMPs and aquifer conditions were examined along with various real operational aspects of SAT systems, including hydraulic loading rate and dry/wet ratio. The effect of spatial heterogeneity on saturated hydraulic conductivity was considered. Developed GEP models had an average coefficient of determination R² of 0.92. Monte Carlo simulation (MCS) with 50,000 realizations was used to propagate uncertainty in SAT parameters in order to generate stochastic inputs for the GEP model. It was found that the removal of OMPs in SAT systems is mostly affected by biodegradation rate and soil-saturated hydraulic conductivity, in addition to dry/wet ratio. Finally, the developed GEP models were applied to enhance the criteria for selecting potential sites for SAT systems in Egypt considering OMP. It was shown that a SAT system would perform well at three sites, with a OMP removal efficiency reaching 100%, whereas it would have a removal of only 50% in the other two sites. Uncertainties in predictions were quantified with an average value of 35%. The developed GEP models can serve as basis for preliminary SAT site selection and design, and can substitute for complex commercial modeling software, especially for practitioners and decision makers in feasibility studies. However, for SAT implementation in a selected location, results can be confirmed only through field column tests. [ABSTRACT FROM AUTHOR]

Soil Aquifer Treatment (SAT) is used to increase groundwater resources and enhance the water quality of wastewater treatment plant (WWTP) effluents. The resulting water quality needs to be assessed. In this study, we investigate attenuation pathways of nitrogen (N) compounds (predominantly NH 4 +) from a secondary treatment effluent in pilot SAT systems: both a conventional one (SAT-Control system) and one operating with a permeable reactive barrier (PRB) to provide extra dissolved organic carbon to the recharged water. The goal is to evaluate the effectiveness of the two systems regarding N compounds by means of chemical and isotopic tools. Water chemistry (NO 3 −, NH 4 +, Non-Purgeable Dissolved Organic Carbon (NPDOC), and O 2) and isotopic composition of NO 3 − (ẟ 15N–NO 3 - and ẟ 18O–NO 3 -) and NH 4 + (ẟ 15N–NH 4 +) were monitored in the inflow and at three different sections and depths along the aquifer flow path. Chemical and isotopic results suggest that coupled nitrification-denitrification were the principal mechanisms responsible for the migration and distribution of inorganic N in the systems and that nitrification rate decreased with depth. At the end of the study period, 66% of the total N in the solution was removed in the SAT-PRB system and 69% in the SAT-Control system, measured at the outlet of the systems. The residual N in solution in the SAT-PRB system had an approximately equal proportion of N–NH 4 + and N–NO 3 - while in the SAT-Control system, the residual N in solution was primarily N–NO 3 -. Isotopic data also confirmed complete NO 3 − degradation in the systems from July to September with the possibility of mixing newly generated NO 3 − with the residual NO 3 − in the substrate pool. • We applied isotopic tools in pilot soil aquifer treatment systems to evaluate the N cycle. • Simultaneous nitrification-denitrification was the principal N attenuation pathway. • Nitrification occurred at the top of the system due to vertical diffusion of O 2. • Denitrification was enhanced by the increase of dissolved organic carbon and temperatures. • Limitations in using isotopic tools to quantify multiple reactions were observed. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment is widely applied to improve the quality of treated wastewater in its reuse as alternative source of water. To gain a deeper understanding of the fate of thereby introduced organic micropollutants, the attenuation of 28 compounds was investigated in column experiments using two large scale column systems in duplicate. The influence of increasing proportions of solid organic matter (0.04% vs. 0.17%) and decreasing redox potentials (denitrification vs. iron reduction) was studied by introducing a layer of compost. Secondary effluent from a wastewater treatment plant was used as water matrix for simulating soil aquifer treatment. For neutral and anionic compounds, sorption generally increases with the compound hydrophobicity and the solid organic matter in the column system. Organic cations showed the highest attenuation. Among them, breakthroughs were only registered for the cationic beta-blockers atenolol and metoprolol. An enhanced degradation in the columns with organic infiltration layer was observed for the majority of the compounds, suggesting an improved degradation for higher levels of biodegradable dissolved organic carbon. Solely the degradation of sulfamethoxazole could clearly be attributed to redox effects (when reaching iron reducing conditions). The study provides valuable insights into the attenuation potential for a wide spectrum of organic micropollutants under realistic soil aquifer treatment conditions. Furthermore, the introduction of the compost layer generally showed positive effects on the removal of compounds preferentially degraded under reducing conditions and also increases the residence times in the soil aquifer treatment system via sorption. [ABSTRACT FROM AUTHOR]

A permeable reactive layer was installed at the floor of an infiltration basin. The reactive layer comprised 1) vegetable compost to provide a sorption surface for neutral organic compounds and to release easily degradable organic matter, thus generating a sequence of redox states, and 2) minor amounts of clay and iron oxide to increase sorption of cationic and anionic species, respectively. Field application of this design was successful in generating denitrification, and manganese-, and iron-reducing conditions beneath the basin. This, together with the increase in types of sorption sites, may explain the improved removal of three of the four selected pharmaceuticals compared with their behavior prior to installation of the layer. After installation of the reactive layer, atenolol concentrations were below the detection limits in the vadose zone. Moreover, concentrations of gemfibrozil and cetirizine were reduced to 20% and 40% of their initial concentrations, respectively, after 200 h of residence time. In contrast, prior to installation of the reactive layer, the concentrations of these three pharmaceuticals in both the vadose zone and the aquifer were more than 60% of the initial concentration. Carbamazepine exhibited recalcitrant behavior both prior to and after the reactive barrier installation. [ABSTRACT FROM AUTHOR]

Abstract: Ozonation is known as an efficient treatment to reduce the concentration of many trace organic compounds from WWTP effluents, but the formation of unknown and possibly persistent and toxic transformation products has to be considered. In this paper tertiary treatment of wastewater by the combination of ozone and soil aquifer treatment was investigated with respect to the removal of the antiepileptic drug carbamazepine (CBZ, 10 μg/L) and its transformation products. Batch tests and pilot experiments confirmed efficient removal of carbamazepine from secondary effluent by ozone. With typical ozone consumption of 0.7 mg O3/mg DOC0, approx. 50% of the transformed CBZ was detected as its primary product 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM). Structure proposals and a formation pathway were elaborated for a total of 13 ozonation products of CBZ. In subsequent biological treatment BQM turned out to be more effectively biodegraded than CBZ. Its aldehyde group was quickly oxidized to a carboxylic acid (BaQM), which was removed in sand column experiments. Most of the minor ozonation products of CBZ persisted in sand column experiments with residence times of 5–6 days. Non-target screening of column effluent revealed no formation of persistent biotransformation products. [Copyright &y& Elsevier]

To clarify the removal trends of typical pollutants in recharged water samples during soil aquifer treatment (SAT), especially the recharging performances in the funnel areas of arid regions, the Zibo-Weifang funnel area of China was selected as an example where the effects of dry-wet ratio (DWR, the ratio of the dry period to irrigation period), wet period duration (WPD, duration of one irrigation period), irrigation side length (ISL) and irrigation depth (ID) on the 50-year SAT performance were simulated using HYDRUS-2D. Experimental results revealed that the operational parameters of the DWR, WPD, ISL and ID exhibited significant effects on the bulk removal of chemical oxygen demand (COD), nitrate (N O 3 −), ammonium (N H 4 +), total phosphorus (TP) and hexavalent chromium (C r 6 +). Eventually, the optimal conditions with a DWR of 3, WPD of 7 d, ISL of 100 m, and ID of 200 cm were selected for the SAT based on the simulations, and irrigation loads as high as of 84.12 m/yr were obtained. During the 50-year irrigation simulation, as much as 256 Mm3/yr of new water would be recharged into the Shandong Plain, which would be accompanied by the effective removal of COD, N H 4 + , TP and C r 6 + . In contrast, the N O 3 − concentrations within the obtained SAT effluent (50 m depth) were higher than those of the influent, which were closely related to the insufficient carbon sources in the deep soil and poor soil adsorption capacity. Thus, a more stringent threshold value for the nitrate reinjection concentration (e.g., 12 mg/L) was proposed. In addition, the pollutants, N O 3 − , N H 4 + , TP and C r 6 + all exhibited a penetration potential and posed potential pollution threats, especially under higher irrigation loads. Therefore, appropriate pretreatment measures should be strongly considered for the practical operation of SAT systems. [Display omitted] • Simulated the efficiency of SAT in different operating conditions at actual scale. • N O 3 − concentration increased after SAT under different operating conditions. • The concentration of N O 3 − in influent should be limited to less than 12 mg/L. • Significant correlation existed in the removal of N H 4 + with COD and TP (R 2 >0.8). • The penetration risk exhibited the following trend: N O 3 − ≫ C r 6 + N H 4 + >TP. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify qualitative and quantitative changes in the character of water-extractable organic matter (WEOM) in soils as a consequence of soil aquifer treatment (SAT). Soil samples were obtained from a soil-column system with a 2-year operation, and divided into seven layers from top to bottom: CS1 (0–12.5 cm), CS2 (12.5–25 cm), CS3 (25–50 cm), CS4 (50–75 cm), CS5 (75–100 cm), CS6 (100–125 cm) and CS7 (125–150 cm). A sample of the original soil used to pack the columns was also analysed to determine the effects of SAT. Following 2 years of SAT operation, both soil organic carbon and water-extractable organic carbon were shown to accumulate in the top soil layer (0–12.5 cm), and to decrease in soil layers deeper than 12.5 cm. The WEOM in the top soil layer was characterized by low aromaticity index (AI), low emission humification index (HIX) and low fluorescence efficiency index (Feff). On the other hand, the WEOM in soil layers deeper than 12.5 cm had increased values of HIX andFeff, as well as decreased AI values relative to the original soil before SAT. In all soil layers, the percentage of hydrophobic and transphilic fractions decreased, while that of the hydrophilic fraction increased, as a result of SAT. The production of the amide-2 functional groups was observed in the top soil layer. SAT operation also led to the enrichment of hydrocarbon and amide-1 functional groups, as well as the depletion of oxygen-containing functional groups in soil layers deeper than 12.5 cm. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) is a cost-effective natural wastewater treatment and reuse technology. It is an environmentally friendly technology that does not require chemical usage and is applicable to both developing and developed countries. However, the presence of organic matter, nutrients, and pathogens poses a major health threat to the population exposed to partially treated wastewater or reclaimed water through SAT. Laboratory-based soil column and batch experiments simulating SAT were conducted to examine the influence of temperature variation and oxidation-reduction (redox) conditions on removal of bulk organic matter, nutrients, and indicator microorganisms using primary effluent. While an average dissolved organic carbon (DOC) removal of 17.7 % was achieved in soil columns at 5 °C, removal at higher temperatures increased by 10 % increments with increase in temperature by 5 °C over the range of 15 to 25 °C. Furthermore, soil column and batch experiments conducted under different redox conditions revealed higher DOC removal in aerobic (oxic) experiments compared to anoxic experiments. Aerobic soil columns exhibited DOC removal 15 % higher than that achieved in the anoxic columns, while aerobic batch showed DOC removal 7.8 % higher than the corresponding anoxic batch experiments. Ammonium-nitrogen removal greater than 99 % was observed at 20 and 25 °C, while 89.7 % was removed at 15 °C, but the removal substantially decreased to 8.8 % at 5 °C. While ammonium-nitrogen was attenuated by 99.9 % in aerobic batch reactors carried out at room temperature, anoxic experiments under similar conditions revealed 12.1 % ammonium-nitrogen reduction, corresponding to increase in nitrate-nitrogen and decrease in sulfate concentration. [ABSTRACT FROM AUTHOR]

To further improve the removal of the dissolved organic matter (DOM) in secondary effluent during the laboratory-scale soil aquifer treatment ( SAT), fly-ash (FA) was added to the traditional soil columns as an additive in different proportions and filling patterns. Removal and transformation of the trihalomethanes (THMs) precursors in secondary effluent in the FA-additive SAT system was investigated by the analysis of ultraviolet absorbance at 254 nm (UV254), dissolved organic carbon (DOC), specific ultraviolet light absorbance (SUVA) and excitation-emission matrix (EEM) fluorescence spectroscopy. The FA-additive enhanced the reduction of DOC, UV254, SUVA and THMFP efficiently. The increasing of FA dosage would lead to a high removal efficiency of DOM during SAT operation, but the biodegradation of the columns was negatively affected. Experimental results demonstrated that the combination of FA adsorption and biodegradation in soil could achieve a better removal of DOM. Fluorescence intensity showed that the FA-additive could effectively remove aromatic acid proteins, humic-like and fulvic-like materials (THMs precursors) in secondary effluent. [ABSTRACT FROM AUTHOR]

There is growing concern over the health and environmental effects posed by endocrine disrupting chemicals (EDCs) in the aquatic environment. The removal of three potent EDCs including estrone (E1), 17β-estradiol (E2), and 17α -ethinylestradiol (EE2) in a wastewater using soil columns was investigated. E2 was the most easily removed estrogen, while EE2 was the least removed. Removal efficiencies were improved as the thickness of the unsaturated zone increased whereas increased DOC improved the removal in the saturated columns. Enhanced removal efficiencies were also obtained at lower water flow rates and in the presence of silt and clay. [ABSTRACT FROM AUTHOR]

Abstract: A set of bioassays (acute toxicity to Daphnia, genotoxicity, estrogenic and antiestrogenic toxicity) was used to evaluate the safety of reclaimed water reuse in a lab-scale artificial groundwater recharge system. Ozonation of 1mg O3·(mg DOC)−1 was used as the pretreatment and was proved to be effective in removing the four toxicity, with removal ratios ranging from 56% to 99%. In the vadose layer, the responsible compounds for toxicity were less efficiently removed than the bulk organic compounds. However, they were preferentially removed during the saturated aquifer treatment, with all the toxic effects per carbon mass dropping by 20–50%. Therefore, more than one month traveling in the aquifer is suggested before water reuse. Since UV254 was significantly correlated with the toxicity data, it could serve as an indicator of the toxicity. With the bioassay-based safety evaluation, the combination of soil aquifer treatment and ozonation could provide new water sources with no higher toxic than the conventional natural drinking water source. [Copyright &y& Elsevier]

Soil aquifer treatment (SAT) using primary effluent (PE) is an attractive option for wastewater treatment and reuse in many developing countries with no or minimal wastewater treatment. One of the main limitations of SAT of PE is rapid clogging of the infiltration basin due to high suspended solid concentrations. Some pre-treatment of PE before infiltration is likely to reduce this limitation, improve performance of SAT and help to implement this technology effectively. The effects of three pre-treatment options namely sedimentation (SED), coagulation (COAG) and horizontal roughing filtration (HRF) on SAT were analyzed by conducting laboratory-scale batch and soil column experiments. The sedimentation and coagulation pre-treatments led to less head loss development and reduction of clogging effect. The head loss development in soil column using PE + COAG and PE + SED was reduced by 85 and 72%, respectively, compared to PE alone without any pretreatment. The overall dissolved organic carbon (DOC) removal of pre-treatments and soil column collectively were 34, 44, 51 and 43.5% for PE without any pre-treatment, PE + SED, PE + COAG and PE + HRF, respectively. Coagulation pre-treatment of PE was found to be the most effective option in terms of suspended solids, DOC and nitrogen removal. Sedimentation pre-treatment of PE could be attractive where land is relatively less expensive for the construction of sedimentation basins. [ABSTRACT FROM AUTHOR]

Abstract: A 2000 mm long saturated laboratory soil column was used to simulate soil aquifer treatment under saturated conditions to assess the removal of chemical and biochemical oxygen demand (COD and BOD), dissolved organic carbon (DOC), nitrogen and phosphate, using high strength artificial wastewater. The removal rates were determined under a combination of constant hydraulic loading rates (HLR) and variable COD concentrations as well as variable HLR under a constant COD. Within the range of COD concentrations considered (42 mg L−1–135 mg L−1) it was found that at fixed hydraulic loading rate, a decrease in the influent concentrations of dissolved organic carbon (DOC), biochemical oxygen demand (BOD), total nitrogen and phosphate improved their removal efficiencies. At the high COD concentrations applied residence times influenced the redox conditions in the soil column. Long residence times were detrimental to the removal process for COD, BOD and DOC as anoxic processes and sulphate reduction played an important role as electron acceptors. It was found that total COD mass loading within the range of 911 mg d−1–1780 mg d−1 applied as low COD wastewater infiltrated coupled with short residence times would provide better effluent quality than the same mass applied as a COD with higher concentration at long residence times. The opposite was true for organic nitrogen where relatively high concentrations coupled with long residence time gave better removal efficiency. [Copyright &y& Elsevier]

Summary: Irrigation with treated wastewater (TWW) has been reported to induce low to moderate hydrophobicity in soils of different texture with or without vegetation cover. Additional potential sites for adverse effects of TWW are infiltration basins, where TWW undergoes tertiary treatment, known as soil aquifer treatment (SAT). The annual organic matter (OM) loads in SAT are a hundred fold higher than those applied in irrigation with TWW. Therefore, we initially presumed that in the sandy soils of SAT infiltration basins, hydrophobicity would be expressed to a higher extent and would further affect the hydraulic properties of these soils. This hypothesis was tested in the Dan Region Wastewater Reclamation Project, Tel-Aviv, Israel. In terms of water drop penetration time (WDPT) test, the results obtained exhibited similar hydrophobicity levels (0⩽WDPT⩽238s) to those obtained in the TWW irrigated fields and in a similar manner, soil hydrophobicity was only exhibited in the surface soil layer. It is suggested that the low to moderate hydrophobicity obtained under TWW irrigation and recharge into the SAT basins, may primarily stem from the drying and wetting cycle regimes employed. Under these conditions, hydrophobic compounds, which may impart hydrophobicity to the soil particles, are likely to detach and dissolve into the soil solution at the subsequent irrigation or recharge event. Furthermore, the frequent displacement of the resident TWW derived OM by repeatedly flooding events, prevents maturation and humification of the resident OM. Further investigations on the hydraulic properties of the basin soils were conducted in conjunction with the solid–liquid contact angle (ω) and the surface tension (γ L) of the soil solution. The results obtained imply that the dependence of the hydraulic properties on ω and/or γ L, can be attributed to the hydrophobic nature of both the solid and dissolved OM originating from the recharged TWW. [Copyright &y& Elsevier]

Results from a direct recharge experiment conducted in the field to investigate DOC and UVA254 attenuation rates during the direct injection of UF treated wastewater into a artificial coastal sandfill are presented in this paper. Approximately 500m3 of ultra-filtered wastewater was injected into the saturated zone, over a period of 9 days. The movement of the plume was tracked over 80 days, during which time samples were obtained from multilevel samplers installed in transects across the drift axis of the plume. An analysis of fluorescein in the samples obtained during the drift of the UF plume showed that DOC and UVA were attenuated beyond rates predicted by conservative mixing, by up to a maximum of 45%. A degradation coefficient of 0.0175 day-1 was found to be applicable for DOC degradation. After a drift period of 80 days, DOC and UVA reduced to approximately 4.5 mg/l and 0.100cm-1, respectively, from initial values of 8.06 mg/l and 0.199cm-1. [ABSTRACT FROM AUTHOR]

There are current concerns about the presence of persistent chemicals in recharge water used in soil aquifer treatment systems. Triclocarban (TCC) has been reported as a persistent, high production volume chemical with the potential to bioaccumulate in the environment. It is also known to have adverse effects such as toxicity and suspected endocrine disruption. This study was carried out to study the fate of TCC in soil aquifer treatment (SAT) through laboratory simulations in a soil column. The system performance was evaluated with regards to TCC influent concentration, sand (column) depth, and residence time. Results obtained confirmed the ability of SAT to reduce TCC concentrations in wastewater. Sorption and biodegradation were responsible for TCC removal, the latter mechanism however being unsustainable. The removal efficiency was found to be dependent on concentration and decreased over time and increased with column depth. Within the duration of the experimental run, TCC negatively impacted on treatment performance through a reduction in COD removals observed in the column. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) and bank filtration use natural attenuation processes to purify water for subsequent use. Soil aquifer treatment may constitute both unsaturated and saturated flow conditions, while bank filtration systems are primarily saturated flow. This analysis focuses on the saturated zone, where the majority of residence time occurs, in both SAT and bank filtration systems. Sustainable removal mechanisms during subsurface flow are primarily surface-mediated and therefore depend on surface area. By analyzing saturated subsurface flow hydraulics in granular media, a relationship between surface area and travel time was developed. For saturated subsurface flow, the ratio of surface area-to-travel time varied by approximately a factor of 3, for common aquifer materials subject to identical hydraulic gradients. Because travel time criteria often are used to regulate SAT and bank filtration systems, these criteria also may determine the surface area and associated surface-mediated reactions for water purification. The ratio of surface area-to-travel time increases with increasing hydraulic gradient, implying that surface area is relatively constant for specific travel times, even if the hydraulic gradient changes; however, the increasing hydraulic gradient will increase the distance from the recharge zone to the recovery well. Therefore, travel time assessments based on maximum possible hydraulic gradients increase surface area and could provide a conservative limit for surface-mediated reactions. This analysis demonstrates that travel time criteria for SAT and bank filtration systems indirectly provide a minimum surface area that may support sustainable removal mechanisms. [ABSTRACT FROM AUTHOR]

A method for the simultaneous determination of seven commonly used artificial sweeteners in water is presented. The analytes were extracted by solid phase extraction using Bakerbond SDB 1 cartridges at pH 3 and analyzed by liquid chromatography electrospray ionization tandem mass spectrometry in negative ionization mode. Ionization was enhanced by post-column addition of the alkaline modifier Tris(hydroxymethyl)amino methane. Except for aspartame and neohesperidin dihydrochalcone, recoveries were higher than 75% in potable water with comparable results for surface water. Matrix effects due to reduced extraction yields in undiluted waste water were negligible for aspartame and neotame but considerable for the other compounds. The widespread distribution of acesulfame, saccharin, cyclamate, and sucralose in the aquatic environment could be proven. Concentrations in two influents of German sewage treatment plants (STPs) were up to 190 μg/L for cyclamate, about 40 μg/L for acesulfame and saccharin, and less than 1 μg/L for sucralose. Removal in the STPs was limited for acesulfame and sucralose and >94% for saccharin and cyclamate. The persistence of some artificial sweeteners during soil aquifer treatment was demonstrated and confirmed their environmental relevance. The use of sucralose and acesulfame as tracers for anthropogenic contamination is conceivable. In German surface waters, acesulfame was the predominant artificial sweetener with concentrations exceeding 2 μg/L. Other sweeteners were detected up to several hundred nanograms per liter in the order saccharin ≈ cyclamate > sucralose. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Soil column experiments were performed to investigate the behavior and characteristics of dissolved organic matter (DOM) during soil aquifer treatment (SAT), and to differentiate among the mechanisms responsible for the changes in the structural and functional properties of DOM during SAT. To determine the biological transformation of DOM, biodegradability tests using a biodegradation-column system were conducted. DOM was fractionated using XAD resins into 5 fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). Dissolved organic carbon (DOC) was removed by 70% during SAT, and the sorption and anaerobic biodegradation in SAT led to a DOC reduction of 27.4%. The significant changes in fluorescence properties of DOM were observed during SAT. However, the sorption and anaerobic biodegradation in SAT seemed to have no significant effect on the chemical structure of fluorescing constituents in DOM. The DOM fractions exhibited different changes in Fourier-transform infrared (FT-IR) spectra characteristics during SAT. Biodegradation resulted in the enrichment of aromatic structures and the decreased content of the oxygen-containing functional groups, such as Cx2013;O, in DOM. On the other hand, the production of C–O and amide-2 functional groups occurred as a result of the sorption combined with anaerobic biodegradation in SAT. [Copyright &y& Elsevier]

Removal of organic matter is a critical parameter in soil aquifer treatment (SAT) as it governs and influences the removal of other contaminants by biodegradation namely trace organics, nitrogen species and microbes. A framework for analysis and prediction of the performance of SAT systems with respect to removal of organic matter under different water quality and process conditions was developed based on an extensive literature review and data analysis. Guidelines were developed to make preliminary estimates of the removal of organic matter during SAT using primary, secondary and tertiary effluents from wastewater treatment plants. These guidelines can be used as a quick tool to analyze the performance of existing SAT systems and serve as a decision support tool for feasibility studies and to save time for further detailed experimentation and design of SAT systems. Furthermore, effects of soil type and redox conditions on organic matter removal during SAT were also analyzed. [ABSTRACT FROM AUTHOR]

Bacteria transport and adhesion experiments under water-saturated and partially saturated conditions were examined over a wide range of ionic strength, from 1 to 100 mM KCl, CaCl2, and MgCl2, and at water contents of 0.15 and 0.22 in sand columns packed with three different sands, baked, sterilized, and raw sands in order to investigate the effects of ionic strength, water content, and porous media type on the microbial adhesion in soil aquifer treatment (SAT). Well-characterized Escherichia coli JM109 were used as model bacterial cells in this study. Column study results showed that bacterial deposition rates increased with increasing ionic strength and decreasing water content, and were higher in raw sand columns than those in other sand columns. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was applied to experimental results in order to consider the interaction energies between the bacterial cells and collector grains; results revealed that a considerable amount of bacterial cells was weakly deposited onto the solid surfaces in secondary minimum. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) is a promising technique for wastewater reclamation and reuse. This treatment strategy takes advantage of physicochemical and biological processes in the subsurface. The model employed in this study is based on MODFLOW-SURFACT (HydroGeoLogic, Inc.), a three-dimensional model for variably saturated flow and reactive mass transport. The model accounts for reactions including the nitrification of ammonium, the denitrification of nitrate, and the oxidation of organic carbon. Concentration of dissolved oxygen and biomasses involved in aerobic and anaerobic biological reactions forms the basis for estimates of nonlinear reaction rates formulated using a multiple-Monod expression. Illustrative simulations were conducted in a two-dimensional cross-sectional domain, with unsaturated and saturated zones. They examine the effects that site and operational conditions have on the performance of a SAT system. The parameters and conditions of concern included length of the wet/dry cycle, ground surface condition, and infiltration rate. From the simulations, we found that organic carbon was effectively removed in all cases. The availability of oxygen was a key factor in predicting the production and removal of nitrate. Overall, the model successfully described the fate and transport of the key constituents during the wet/dry operational periods in both unsaturated and saturated subsurface. [ABSTRACT FROM AUTHOR]

The Rapid Infiltration and Extraction (RIX) facility, a soil aquifer treatment system, began taking secondary effluent from the City of San Bernardino, California, in 1996. The gradual decrease in the hydraulic conductivity of the infiltration basins at RIX has been attributed to the accumulation of organic matter in the surface sand. Periodic tillage of the surface sand to restore the permeability has mixed this organic matter to a depth of nearly 50 cm. We hypothesized that in situ chemical oxidation of the surface sand might improve the infiltration rate and increase the time between filling and drying cycles. The effect of organic matter oxidation on sand permeability was tested in laboratory sand columns treated with sodium hypochlorite, calcium hypochorite, and ozone gas. All oxidants significantly decreased the hydraulic conductivity of the surface sand. The loss in permeability was attributed to an increase in dispersed clay plus silt-sized particles that were released as a result of oxidation. This study suggests that ex situ sand-washing operations, currently being used to clean the sand, could be improved by the addition of oxidants to the wash water. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) is an established and sustainable wastewater treatment approach for water reuse that has been gaining increased attention in various countries around the world. Increasing volumes of domestic wastewater and escalating real estate prices around urban areas emphasize the urgent need to maximize the treatment efficiency by revisiting the SAT setup. In this study, a novel approach was examined to increase biodegradation rates and improve the quality of SAT topsoil effluent. Experiments with midscale, custom-made columns were carried out with sand collected from an operational SAT and a highly permeable natural material with high internal porosity, tuff, which was maturated (i.e., buried in the SAT infiltration basin) for 3 months. The filtration efficiency, biodegradation rates of organic material, microbial diversity, and outflow quality were compared between the operational SAT sand and the tuff using state-of-the-art approaches. The results of this study indicate that biodegradation rates (9.2 µg C g−1d−1) and filtration efficiency were up to 2.5-fold higher within the tuff than the SAT sand. Furthermore, the biofilm community was markedly different between the two media, giving additional insights into the bacterial phyla responsible for biodegradation. The results highlight the advantage of using highly porous material to enhance the SAT filtration efficiency without extending the topsoil volume. Hence, infusing a permeable medium, comprising highly porous material, into the SAT topsoil could offer a simple approach to upgrade an already advantageous SAT in both developed and developing countries. [ABSTRACT FROM AUTHOR]

Water reclamation through the use of soil aquifer treatment (SAT) is a sustainable water management technique with high potential for application in many regions worldwide. However, the fate of contaminants of emerging concern (CECs) during the infiltration of treated wastewater during SAT is still a matter of research. This study investigates the removal capacity of 27 CECs during SAT by means of infiltration experiments into a 6 m soil column. Additionally, the influence of the hydraulic operation of SAT systems on the removal of CECs is investigated by changing the wetting and drying cycle lengths. Sixteen out of 27 CECs are efficiently removed during SAT under various operational modes, e.g., bezafibrate, diclofenac and valsartan. For six substances (4-methylbenzotriazole, amidotrizoic acid, benzotriazole, candesartan, hydrochlorothiazide and sulfamethoxazole), removal increased with longer drying times. Removal of amidotrizoic acid and benzotriazole increased by 85% when the drying cycle was changed from 100 to 444 min. For candesartan and hydrochlorothiazide, removal improved by 35%, and for 4-methylbenzotriazole and sulfamethoxazole, by 57% and 39%, respectively. Thus, enhanced aeration of the vadose soil zone through prolonged drying times can be a suitable technique to increase the removal of CECs during SAT. [ABSTRACT FROM AUTHOR]

Increased water demands have led to a notable interest in the use of treated wastewater for reuse. Typically, this results from the implementation of advanced treatment of final effluent from wastewater treatment plants prior to reuse for potable or non-potable purposes. Soil aquifer treatment (SAT) is a natural treatment process in which water from sources of varying quality is infiltrated into the soil to further improve its quality. The goal of this study was to determine the log 10 reduction values (LRVs) of viruses naturally present in treated effluent and evaluate two potential indicators of virus removal and transport, pepper mild mottle virus (PMMoV) and crAssphage, during SAT of treated effluent. Groundwater was sampled at three wells with different attributes within the Sweetwater Recharge Facility (SWRF) in Tucson, AZ. These sites vary greatly in operational parameters such as effluent infiltration rates and wetting/drying cycles, which may influence virus removal efficiency. Detection of adenovirus, enterovirus, PMMoV, and crAssphage were determined by qPCR/RT-qPCR and log 10 reduction values (LRVs) were determined. PMMoV and crAssphage were detected in groundwater associated with a set of recharge basins that exhibited shorter wetting/drying cycles and faster infiltration rates. LRVs for crAssphage and PMMoV at this site ranged from 3.9 to 5.8, respectively. Moreover, PMMoV was detected downflow of the SAT sites, indicating the potential degradation of microbial groundwater quality in the region surrounding managed aquifer recharge facilities. Overall, PMMoV and crAssphage showed potential as conservative process indicators of virus removal during SAT, particularly for attribution of LRV credits. Moreover, the detection of these viruses indicated the potential influence of wetting/drying cycles on virus removal by SAT, a parameter that has not yet been studied with respect to biological contaminants. Image 1 • Virus removal examined at three sites within soil aquifer (SAT) treatment facility. • Overall virus removal ranged from >3.4 to >6.2 • Virus detected from site with faster infiltration rates/shorter wet-dry cycles. • Pepper mild mottle virus and crAssphage have potential as process indicators of virus removal. • Pepper mild mottle virus detected in groundwater downflow of SAT facility. [ABSTRACT FROM AUTHOR]

Soil aquifer treatment (SAT) is an effective indirect technique for wastewater reuse. The present study aims at assessing the soil capacity in arid region of Varamin on natural attenuation of inorganic constituents of municipal treated wastewater of Tehran City. In order to simulate SAT pond, four columns of 30 cm in height and 4 cm in diameter were filled with sandy loam soil taken from artificial recharge pond in Varamin plain. These columns were recharged by secondary treated wastewater from Shahre-Rey treatment plant under the plan of 12-h wetting and drying cycles. During the experiment, 50 pore volume passed through each column. The pH, EC, TDS, SAL, SAR, major ions, nitrate, phosphate and trace elements were measured in influent and effluent samples. The concentration of Na+, Ca2+, Mg2+, Cl− and SO42− increased in effluent samples due to a washout process and dissolution of minerals. The soil could only attenuate NO3−, K+, Rb and PO43− with the percentage of 18.4, 24.6, 67.7 and 83.6, respectively. The soil of studied area is rich in Cr, Ni, Sr, Pb, Cu, Zn, Ba and Rb. The concentrations of all mentioned trace elements, with the exception of Rb, have increased in the effluent samples with respect to influent. Also, the quality indices of TDS, SAL and SAR have increased 10.6, 25.2 and 8.7%, respectively, in effluent. Soil column samples, at the end of experiment, contain high amounts of major and trace elements. Consequently, there is a potential risk for groundwater contamination in long-term recharge. [ABSTRACT FROM AUTHOR]