Soil Aquifer Treatment System Research Articles

Fate and transport of carbamazepine in soil aquifer treatment (SAT) infiltration basin soils

The transport and fate of the pharmaceutical carbamazepine (CBZ) were investigated in the Dan Region Reclamation Project (SHAFDAN), Tel-Aviv, Israel. Soil samples were taken from seven subsections of soil profiles (150 cm) in infiltration basins of a soil aquifer treatment (SAT) system. The transport characteristics were studied from the release dynamics of soil-resident CBZ and, subsequently, from applying a pulse input of wastewater containing CBZ. In addition, a monitoring study was performed to evaluate the fate of CBZ after the SAT. Results of this study indicate adsorption, and consequently retardation, in CBZ transport through the top soil layer (0–5 cm) and to a lesser extent in the second layer (5–25 cm), but not in deeper soil layers (25–150 cm). The soluble and adsorbed fractions of CBZ obtained from the two upper soil layers comprised 45% of the total CBZ content in the entire soil profile. This behavior correlated to the higher organic matter content observed in the upper soil layers (0–25 cm). It is therefore deduced that when accounting for the full flow path of CBZ through the vadose zone to the groundwater region, the overall transport of CBZ in the SAT system is essentially conservative. The monitoring study revealed that the average concentration of CBZ decreased from 1094 ± 166 ng L −1 in the recharged wastewater to 560 ± 175 ng L −1 after the SAT. This reduction is explained by dilution of the recharged wastewater with resident groundwater, which may occur as it flows to active reclamation wells.

Fate of triclocarban during soil aquifer treatment: soil column studies

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.

Long-term accumulation and material balance of organic matter in the soil of an effluent infiltration basin

The fate of organic matter (OM) in large-scale infiltration basins used for wastewater treatment by the soil aquifer treatment (SAT) system was investigated. Measured changes in the organic matter concentrations in the soil profiles of the infiltration basins and detailed long-term records of OM concentrations in the recharged effluent and in the observation wells and recovery wells water, were used to calculate OM material balances in the SHAFDAN wastewater treatment plant, serving the City of Tel-Aviv, Israel, since 1977. The average annual total organic matter (TOM) load delivered by the effluents to the soil was ~ 5 kg m − 2 y − 1 . Soil OM concentrations increased from 0.11% in the pristine soil to ~ 0.8% and ~ 0.6%, in the 0–0.15 m and 0.15–0.30 m soil layers, respectively, after ~ 20 y of effluent recharge, but did not change significantly in the 1.80–2.10 m deep layer. The OM accumulation rates in the top two soil layers were fast initially, then declined slowly and the OM concentrations approached a steady state following 10–15 y of effluent recharge. This suggests that stabilization of the ‘active biofilm’ layer in the infiltration basins' soils is a relatively slow process. Material-balance calculations showed, that accumulated OM in the top 0–2.1 m soil layer amounted to only ~ 4% of the TOM added by the effluents during ~ 20 y of recharge. Along the flow pathway of the effluent through the vertical 50–100 m thick soil-sediment column, DOC concentrations decreased by 70–90% (from ~ 18.9 mg L − 1 to ~ 3.7 mg L − 1 ). Continued flow in the aquifer from the observation wells to the recovery wells further decreased DOC concentrations by about 50% (from ~ 3.7 to ~ 1.5 mg L − 1 ).

Framework for assessment of performance of soil aquifer treatment systems

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.

Manganese Mobilization and Enrichment during Soil Aquifer Treatment (SAT) of Effluents, the Dan Region Sewage Reclamation Project (Shafdan), Israel

The composition of groundwater reclaimed from tertiary soil aquifer treatment systems reflects the dynamic processes taking place in the subsurface, between the infiltration basin and the production wells. At the end of year 2000, following more than a decade of operation, high Mn concentrations (2 micromol L(-1) < or = Mn < or = 40 micromol L(-1)) appeared in the reclaimed effluents of the Dan Region Sewage Reclamation Project (Shafdan), Israel. A mass balance indicates that the high Mn excess originated from the aquifer rocks, most likely following reduction of sedimentary Mn-oxides under suboxic conditions. The subsequent adsorption of the Mn2+ results in a slow Mn2+ front that advances in the direction of groundwater flow only when all the Mn2+ exchangeable sites are saturated. A retardation factor obtained from two independent estimates based on a simple reduction-adsorption-advection model yields a value of about 10. This explains the delayed appearance of the high Mn concentrations at a distance of only -500 m from the infiltration basin.

Character of Organic Matter in Soil-Aquifer Treatment Systems

The objective of this study was to investigate the character and fate of bulk organics in reclaimed water used for groundwater recharge via soil-aquifer treatment (SAT). The study design followed a watershed guided approach considering hydraulically corresponding samples of drinking water sources, SAT-applied wastewater effluents, and subsequent post-SAT samples representing a series of different travel times in the subsurface. Water samples were fractionated into hydrophobic acids, transphilic acids, and hydrophilic carbon using a XAD resin-based protocol. Extensive characterization of organic carbon in the different samples was performed using state-of-the-art analytical techniques including excitation–emission matrix fluorescence spectroscopy, size exclusion chromatography, carbon-13 nuclear magnetic resonance spectroscopy ( C-NMR 13 ) , Fourier transform infrared spectroscopy (FTIR), and elemental analysis. During SAT, transphilic and hydrophilic organic matter were preferentially removed. The results...

Studies of P accumulation in soil/sediment profiles used for large‐scale wastewater reclamation

AbstractWe studied the long‐term accumulation processes and material balances of phosphorus (P) in the soil/sediment profiles of large‐scale effluent recharge basins used for wastewater reclamation by the soil aquifer treatment (SAT) system. The objective was to quantify and clarify the long‐term performance of soil/sediment in the SAT system as a sorbent to filter out P from the recharged effluent. Total P concentration in the soil/sediment profiles of the Shafdan wastewater treatment plant (WWTP) increased over 25 years of operation (1977–2001) by 20–220 mg kg−1, as a result of adding loads of 0.17–6.2 kg m−2 of P. Retained P in the 0–2.0 m soil layer increased from 0.06 to 0.31 kg m−2 with increasing cumulative load of P while the retained percentage gradually decreased from 19 to 5% of the cumulative P load. Accumulation rate of P in the 0–0.15 m horizon in the basins was inversely proportional to recharge time, decreasing from ∼28 mg P kg−1 year−1 during the first 3 years of operation, to &lt;2.3 mg P kg−1 year−1 between the 20th and 25th years of operation. Thus, P content in this horizon approached a steady state after about 10–15 years of effluent recharge under the operational conditions of the Shafdan WWTP. Phosphorus concentration in deeper horizons increased at constant rates of approximately 7.8, 5.9 and 2.9 mg P kg −1 year−1 in the 0.15–0.30, 0.30–0.60 and 1.80 to 2.10‐m horizons, respectively, over the 25 years of effluent recharge. However, the accumulation front of P appears gradually to have moved deeper in the soil profile. In general, this phenomenon may be explained by kinetic limitations to the achievement of full adsorption equilibrium for P between the flowing solution and the solid phase components of the soil. In addition, both the increase of EPC0(the equilibrium P concentration in solution at which there is no sorption or desorption to or from the soil under the given conditions), caused by long‐term effluent recharge, and gradual decrease of the annual average concentration of P in the effluent input after 1995, may result in the steady‐state level of P in the topsoil of the basin.

Phosphorous retardation and breakthrough into well water in a soil-aquifer treatment (SAT) system used for large-scale wastewater reclamation

Retardation and breakthrough of phosphorous in the soil/sediment profiles of a SAT system at the Shafdan wastewater treatment plant, Israel, were investigated in situ. Area-weighted average effluent load to the whole site was 65 m yr −1. Annual average concentrations of P in the recharged effluent ranged between about 1.5 and 7.7 mg L −1 during 25 yr of operation, while P in groundwater remained ⩽0.05 mg L −1 in most wells. Recharge is done through an overlying layer of >40 m sandy soil/sediment formations. By combining results of isotherm tests, long-term monitoring of phosphorous (P) in solid and liquid phases of the recharge site, a simple multi-cell tracer-movement model and measured chloride breakthrough curves to the groundwater we calculated P distribution coefficients and estimated the retardation factor of P. Laboratory measured, isotherm-based distribution coefficient, K d I , was about 4–6 L kg −1 at equilibrium P concentration <6 mg L −1, while field-based K d F was considerably higher, reaching about 20–55 L kg −1 after a load of around 1800 m effluent was recharged. Measured P breakthrough times into two shallow observation wells were 19–21 yr. Calculated P breakthrough times using K d F data agreed with observations while those calculated using K d I grossly underestimated retardation and predicted much shorter breakthrough times. This validated the approach and model used. Estimated P breakthrough times to the deeper observation wells and the recovery wells are more than 100 yr and 400–1100 yr, respectively. These estimates show that P contamination of the reclaimed effluents in the Shafdan plant will not be a problem in the foreseeable future.

Role of aquifer storage in water reuse

Two case studies are described that explain the role, value, limitations and policy requirements for storing reclaimed water in aquifers for indirect reuse. The first case involves aquifer storage and recovery of water, the product of tertiary treated municipal sewage effluent, via a single injection and recovery well at Bolivar, South Australia. The recovered water, like the source water for injection, is used for unrestricted irrigation of horticulture. A limestone aquifer at a depth of 100 to 160 m confined by clay and containing brackish groundwater provides the storage zone. In the second case, located at Alice Springs, trials are proceeding to assist in the design and establishment of a soil–aquifer treatment system which will allow water derived from secondary treatment of municipal sewage effluent to be stored in an unconfined alluvial aquifer for irrigation of horticulture. Intermittent infiltration from basins provides supplementary water treatment. In each case, the motivations, choice of methods, required investigations, public consultation processes, and economics of subsurface storage are presented. The lessons learned that may assist with development of policies to facilitate environmentally sustainable subsurface storage of water in water reuse projects are discussed.

Effect of Long-Term Effluent Recharge on Phosphate Sorption by Soils in a Wastewater Reclamation Plant

The Soreq recharge basins, used for wastewater reclamation employing the Soil-Aquifer Treatment (SAT) system, have been recharged, on average, by about 1,800 m depth of secondary effluent during their operation period of ∼25 years. An estimated amount of ∼6 kg P m−2 was added to the soil/sediment column during this period. The objective of this study was to compare phosphorous sorption characteristics of representative pristine soils in the Soreq recharge site to those of the basin soils sampled after a long period of effluent recharge. Batch isotherm experiments were conducted: samples of one g of soil were equilibrated with 25 mL of 0.02 M NaCl solution containing 0–3.2 mM of phosphate for 7 days at 25± 1∘C and P sorption was measured. Long-term effluent recharge significantly decreased the maximum P sorption capacity of the top sandy soil (0.15–0.3 m) and only very slightly decreased maximum P isotherm capacity of the deep clayey-sand soil (10–10.5 m). The retention of P in the basin sandy soil primarily involved sorption and surface precipitation reactions on soil carbonates. In the basin clayey-sand soil, P was retained by its sorption on surfaces of Fe, Al, Mn oxide/hydroxides and clay minerals. Long-term effluent recharge increased EPC0, (the equilibrium P concentration in solution at which there is no sorption or desorption to or from the soil under the given conditions), of the basin soils compared to the pristine soils. Due to loading of the top horizons with P by prolonged recharge and reduced P concentration in the effluent, EPC0 of the basin sandy soil is now equal to the average P concentration of the recharged effluents. If effluent P concentration will decrease further, the top sandy soil will become a source of P to the reclaimed water, rather than a sink. The clayey-sand layers and lenses in the vadose zone of the SAT system of the Soreq site offer a large capacity for P adsorption. With gradual leaching of carbonate minerals and synthesis of secondary clay minerals, driven by long-term effluent recharge, P retention mechanisms in the basin soil may be changed, but this process would be extremely slow.

Utility of Column Lysimeter for Design of Soil Aquifer Treatment System for Wastewater Renovation Using Artificial Neural Networks

An artificial neural network (ANN) model is developed to study the correlation of data with reference to various wastewater pollution parameters (biochemical oxygen demand, chemical oxygen demand, suspended solids, NH4, PO4) using two scales of experiments viz. column lysimeter and a pilot soil aquifer treatment (SAT) system for wastewater renovation in India. A unique feature of the study is that the primary treated wastewater was directly applied to SAT system for renovation in contrast to the secondary treated effluent used in most of the other studies that have been reported. The analysis of data using ANN as a tool indicates that the column lysimeter data are useful for design of SAT systems and it is possible to predict the effluent quality for SAT system based on the inputs from lysimeter experiments. The study highlights the utility of column lysimeter studies for evolving design parameters for a full-scale SAT system thereby obviating the need for pilot SAT studies which are site specific, time consuming, and expensive. Thus, the study suggests that the experimental data from lysimeter studies at a particular site can be used to predict performance of field-scale SAT systems without going in for actual experimentation. Further, the field data from one site could be utilized for design of SAT systems at other locations provided the climatic and hydrogeological conditions viz. soil matrix characteristics and wastewater characteristics, etc., are similar.

Heavy metal retention and partitioning in a large-scale soil-aquifer treatment (SAT) system used for wastewater reclamation

Soil aquifer treatment (SAT) of wastewater relies on extensive biogeochemical processes in the soil and aquifer to achieve large-scale and economic reclamation of municipal effluents. Removal of trace metals from the wastewater is a prime objective in the operation, but the long-term sustainability of the adsorptive filtration capacity of the soils is an open question. Solid/solution partitioning (measured by the distribution coefficient, K d) and solid/solid partitioning (measured by selective sequential dissolution, SSD) of heavy metals were measured in soils sampled from active recharge basins in a wastewater reclamation plant and were compared to the adjacent pristine dune. K d values for the adsorption of Cu, Ni and Zn, measured in short-term adsorption experiments positively and significantly correlated with solution pH. Quantitative estimation of Cu, Ni and Zn adsorption on multi-sorbents indicated that surface adsorption and precipitation on Fe oxides and/or carbonate may be the major mechanisms of metal retention in these soils. SSD analyses of metal partitioning in soils exposed to ∼20 yr of effluent recharge showed that all solid-phase components, including the most stable ‘residual’ component, competed for and retained added Cu and Zn. Copper preferentially partitioned into the oxide component (32.0% of the soil-accumulated metal) while Zn preferentially partitioned into the carbonate component (51.6% of the soil-accumulated metal).

Sorption behaviors of heavy metals in SAT (soil aquifer treatment) system

Degradation or detoxification of pollutants by SAT system was generally focused on organic contaminants although the regulation of water reuse has provisions of heavy metals. This study is to evaluate the feasibility of SAT for metals such as Cd, Cr and Pb with the pilot scaled column experiment. The desorption possibility of sorbed metals was also examined in the condition of continuous water and even acidic water (pH 4.3) injection. Fractional factorial analysis is a tool frequently used to identify factors or variables that have an effect on a certain response. A two-level fractional factorial analysis was planned to study the effect of four factors on Pb sorption from the experiments; soil particle size, TOC in solution, Pb concentration in solution and flow rate. The main effects among the factors were obtained by ANOVA based MINITAB software. The effects of four factors were also converted into coefficients; those values may build an empirical model to predict the metal sorption of soils.

Assessing the removal potential of soil-aquifer treatment systems for bulk organic matter

The fate of effluent organic matter (EfOM) during groundwater recharge was investigated by studying the removal behavior of four bulk organic carbon fractions isolated from a secondary effluent: Hydrophilic organic matter (HPI), hydrophobic acids (HPO-A), colloidal organic matter (OM), and soluble microbial products (SMPs). Short-term removal of the bulk organic fractions during soil infiltration was simulated in biologically active soil columns. Results revealed that the four organic fractions showed a significantly different behavior with respect to biological removal. HPI and colloidal OM were prone to biological removal during initial soil infiltration (0-30 cm) and supported soil microbial biomass growth in the infiltrative surface. Additionally, colloidal OM was partly removed by physical adsorption or filtration. HPO-A and SMPs reacted recalcitrant towards biological degradation as indicated by low soil biomass activity responses. Adsorbability assessment of the biologically refractory portions of the fractions onto powered activated carbon (PAC) indicated that physical removal is not likely to play a significantly role in further diminishing recalcitrant HPO-A, HPI and SMPs during longer travel times in the subsurface.

Can chemical oxidation improve the permeability of infiltration basins?

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.

The long-term performance of Soil Aquifer Treatment (SAT) for effluent reuse

An innovative scheme of groundwater recharge for wastewater effluent reuse has been practiced on a large scale in the Dan Region Project in Israel since 1977. The system, referred to as SAT (for Soil Aquifer Treatment), provides advanced treatment prior to effluent reuse for unrestricted irrigation. A major study recently carried out consisted of a comprehensive analysis of the water quality data available in the recharged effluent (before SAT), as well as in observation wells and recovery wells (after SAT). The results obtained with respect to suspended solids, organics and nutrients (nitrogen compounds and phosphorus) are presented and discussed. The main processes occurring in the soil-aquifer system, which are responsible for the removal of the above contaminants are filtration through the upper soil layer, organic matter biodegradation and adsorption, ammonia adsorption and biological nitirification-denitrification, and chemical precipitation and adsorption of phosphorus. The findings of the study have provided valuable information on the above processes and their interaction, and have demonstrated that the SAT system should be considered an attractive method for effluent reuse in areas where hydrogeological conditions are suitable for groundwater recharge via spreading basins.

Water reuse in Israel - the Dan Region Project: evaluation of water quality and reliability of plant's operation

Israel is a semi-arid country with insufficient natural water resources. Wastewater effluent reuse and desalination have become the main source of water to compensate for the future water shortage. Today, between 65 and 70% of wastewater of urban and industrial origin is reused in agriculture after treatment in biological treatment plants around the country. The Dan Region Reclamation Project (Shafdan) is the largest wastewater treatment and reclamation project in Israel. 130 Mm3/yr of reclaimed water is used for unrestricted irrigation after soil aquifer treatment (SAT). Extensive water quality monitoring is performed to keep an efficient and safe wastewater reuse system. After 25 years of operation, the Shafdan deals with the following operational issues on an ongoing basis: Biofouling of the effluent pipelines from the wastewater treatment plant to the SAT, and a lack of capacity in the SAT system. Biofilm growth in the pipelines is controlled by intermittently applying chlorine based compounds at a 10 mg/L dosage for a few hours.

Potable reuse of wastewater effluent through an integrated soil aquifer treatment (SAT) - membrane system

Soil aquifer treatment (SAT) has been shown to provide significant reductions of wastewater effluent organic matter (EfOM). While SAT can renovate wastewater effluent to levels commensurate with potable reuse, SAT represents only a single treatment barrier. Membrane filtration has been demonstrated to be an alternative treatment process for wastewater reclamation. However, the performance of membrane filtration is significantly constrained by membrane fouling, reducing membrane productivity in terms of flux decline. Soil aquifer treatment (SAT) is used as a primary barrier in the reclamation system to remove a complex suite of chemical and biological contaminants in wastewater. This study of membrane filtration of SAT-source waters is intended to determine the benefits of the SAT system in terms of membrane fouling reduction with membrane filtration providing a secondary barrier. Membrane treatment of SAT-recovered water provides a multiple barrier exhibiting additional organic matter removal. Moreover, the SAT system also provides for storage of reclaimed water. The synergy between SAT and membrane treatment has led to the concept of an integrated SAT-membrane system for potable reuse.

MEASUREMENT OF ANAEROBIC AMMONIUM OXIDATION ACTIVITY IN SOIL SYSTEMS AND IDENTIFICATION OF PLANCTOMYCETES

MEASUREMENT OF ANAEROBIC AMMONIUM OXIDATION ACTIVITY IN SOIL SYSTEMS AND IDENTIFICATION OF PLANCTOMYCETESLaboratory experiments were completed to demonstrate anaerobic ammonium oxidation (anammox) activity in soils and to identify the microorganisms believed to be responsible for the observed anammox activity. Soils were obtained from Soil Aquifer Treatment (SAT) systems where reclaimed municipal wastewater was applied to the soils in a controlled manner and nitrogen removal was being observed....Author(s)Joan GablePeter FoxSourceProceedings of the Water Environment FederationSubjectSession 59 Research: Application of Molecular ToolsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2003ISSN1938-6478SICI1938-6478(20030101)2003:7L.636;1-DOI10.2175/193864703784640929Volume / Issue2003 / 7Content sourceWEFTECFirst / last page(s)636 - 645Copyright2003Word count187

Review of Research perspectives in hydraulics and water resources engineering edited by R. Prasad and S. Vedula

This book contains 10 state-of-the-art review articles, four in the area of hydraulics, two in wastewater and water quality modeling issues, and the rest in irrigation and water resources development and management aspects. The articles in the book have been written by alumni of the Indian Institute of Science ~IIS!, Bangalore, India, who are currently working at key scientific institution in India. The personal contributions of the authors in their field were quite obvious from the depth and breadth of reviews presented. The book is a part of the Golden Jubilee celebration of IIS and has been well edited and produced. The book contains a mixture of topics that provide insights into the kind of water-related issues that have been researched in India over the past 2 decades or so. Some articles are relatively short and quite specific ~e.g., ‘‘Wastewater Renovation Using Soil-Aquifer Treatment System’’!, while others are detailed and quite broad ~e.g., ‘‘Water Resources and their Management for Sustainable Agricultural Production in India’’!. The topics included are diverse and not targeted toward a specific interest group. However, they are of current interest to researchers in both developed and developing countries. Each article in the book begins with an abstract followed by a good ‘‘introduction’’ to the topic being reviewed. The authors then quickly discuss some basic concepts and issues related to the topic area, followed by a quite detailed and often excellent review of their work, as well as that of authors from other parts of the world. The reviews presented generally provide a fresh and comprehensive perspective on the topics covered in the book. At the end of each article, there is an extensive and up-to-date list of