Soil Aquifer Treatment Research Articles

Impact of hydraulic loading rate and media type on removal of bulk organic matter and nitrogen from primary effluent in a laboratory-scale soil aquifer treatment system

The effect of hydraulic loading rate (HLR) and media type on the removal of bulk organic matter and nitrogen from primary effluent during soil aquifer treatment was investigated by conducting laboratory-scale soil column studies. Two soil columns packed with silica sand were operated at HLRs of 0.625 and 1.25 m/d, while a third column was packed with dune filtering material and operated at HLR of 1.25 m/d. Bulk organic matter was effectively removed by 47.5 ± 1.2% and 45.1 ± 1.2% in silica sand columns operated at 0.625 and 1.25 m/d, respectively and 57.3 ± 7.6% in dune filtering material column operated at 1.25 m/d. Ammonium-nitrogen reduction of 74.5 ± 18.0% was achieved at 0.625 m/d compared to 39.1 ± 4.3% at 1.25 m/d in silica sand columns, whereas 49.2 ± 5.2% ammonium-nitrogen reduction was attained at 1.25 m/d in the dune filtering material column. Ammonium-nitrogen reduction in the first 3 m was assumed to be dominated by nitrification process evidenced by corresponding increase in nitrate. Part of the ammonium-nitrogen was adsorbed onto the media, which was observed at higher rates between 3 and 5 m in silica sand column operated at HLR of 0.625 m/d and dune filtering material column operated at 1.25 m/d compared to 1.25 m/d silica.

Fate of Bulk Organic Matter, Nitrogen, and Pharmaceutically Active Compounds in Batch Experiments Simulating Soil Aquifer Treatment (SAT) Using Primary Effluent

Reduction of bulk organic matter, nitrogen, and pharmaceutically active compounds from primary effluent during managed aquifer recharge was investigated using laboratory-scale batch reactors. Biologically stable batch reactors were spiked with different concentrations of sodium azide to inhibit biological activity and probe the effect of microbial activity on attenuation of various pollutants of concern. The experimental results obtained revealed that removal of dissolved organic carbon correlated with active microbial biomass. Furthermore, addition of 2 mM of sodium azide affected nitrite-oxidizing bacteria leading to accumulation of nitrite-nitrogen in the reactors while an ammonium-nitrogen reduction of 95.5 % was achieved. Removal efficiencies of the hydrophilic neutral compounds phenacetin, paracetamol, and caffeine were independent of the extent of the active microbial biomass and were >90 % in all reactors, whereas removal of pentoxifylline was dependent on the biological stability of the reactor. However, hydrophobic ionic compounds exhibited removal efficiency >80 % in batch reactors with the highest biological activity as evidenced by high concentration of adenosine triphosphate.

Hydrogeological analysis of the upper Dupi Tila Aquifer, towards the implementation of a managed aquifer-recharge project in Dhaka City, Bangladesh

A preliminary feasibility assessment of managed aquifer-recharge (MAR) techniques was undertaken for Dhaka City, Bangladesh. Considering the top impermeable-layer (TIL) thickness and the land-use classification, four primary MAR techniques have been suggested: (1) soil-aquifer treatment (SAT) for TIL thickness 0–8 m, (2) cascade-type recharge trenches/pits for TIL thickness 9–30 m, (3) aquifer storage, transfer and recovery (ASR/ASTR) for TIL thickness 31–52 m, and (4) use of natural wetlands to recharge water collected from open spaces. The study suggests that recharge trenches and pits will be the most appropriate MAR techniques, which can be implemented in most parts of the recharge area (ca. 277 km2). In case of a recharge trench, the lower parts (15–20 m) that are in direct contact with the aquifer can be backfilled with biosand filters with a reactive layer containing metallic iron (Fe0) to offer pre-treatment of the infiltrated water. In addition to the suggested four techniques, the regional groundwater flow direction, from the northwest and northeast towards Dhaka City, may allow use of the aquifer as a natural treatment and transport medium for groundwater, if spreading basins are installed in the greater Dhaka area.

Removal of dissolved organic carbon and nitrogen during simulated soil aquifer treatment

Soil aquifer treatment was simulated in 1 m laboratory soil columns containing silica sand under saturated and unsaturated soil conditions to examine the effect of travel length through the unsaturated zone on the removal of wastewater organic matter, the effect of soil type on dissolved organic carbon removal and also the type of microorganisms involved in the removal process. Dissolved organic carbon removal and nitrification did enhance when the wastewater travelled a longer length through the unsaturated zone. A similar consortium of microorganisms was found to exist in both saturated and unsaturated columns. Microbial concentrations however were lowest in the soil column containing silt and clay in addition to silica sand. The presence of silt and clay was detrimental to DOC removal efficiency under saturated soil conditions due to their negative effect on the hydraulic performance of the soil column and microbial growth.

Changes in quantity and spectroscopic properties of water-extractable organic matter during soil aquifer treatment

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 (F eff). On the other hand, the WEOM in soil layers deeper than 12.5 cm had increased values of HIX and F eff, 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.

Comparison of Organic Matter Removal from Synthetic and Real Wastewater in a Laboratory-Scale Soil Aquifer Treatment System

In this study, the performance of a laboratory-scale soil aquifer treatment (SAT) system was investigated and treatability studies were done in order to determine organic matter removal from synthetic wastewater (SWW) and secondary treated real wastewater (RWW). The SAT system was constructed in laboratory conditions and treatability studies were conducted using soil columns, which were packed with silt loam soil samples. Each column was equipped with a series of ports at multiple depths from soil surface (10, 20, 30, 50, and 75 cm) to collect water samples. Two operational cycles were applied to represent the influence of different wetting and drying periods during wastewater application. Dissolved oxygen, chemical oxygen demand (COD), and total organic carbon (TOC) concentrations were measured in all samples. Average removal values of 61.4 % (COD) and 68.2 % (TOC) were achieved by in SWW and of 58.3 % (COD) and 51.1 % (TOC) in RWW in 55 and 25 weeks of operation, respectively. These results indicated that the performance of the columns operated with SWW was better than the performance of the columns operated with RWW. In essence, the easily biodegradable portion of organic matter was quickly consumed by microorganisms in the first 10 cm of the columns where oxygen levels peaked. Complex organic compounds that are likely to be found in RWW could thus be removed when longer residence times were achieved through the columns. When the removal performances achieved with different operating cycles were compared for each wastewater, it could be seen that longer wetting and longer drying periods yielded higher removal efficiencies in RWW and vice versa in SWW.

Natural Treatment Systems as Sustainable Ecotechnologies for the Developing Countries

The purpose of natural treatment systems is the re-establishment of disturbed ecosystems and their sustainability for benefits to human and nature. The working of natural treatment systems on ecological principles and their sustainability in terms of low cost, low energy consumption, and low mechanical technology is highly desirable. The current review presents pros and cons of the natural treatment systems, their performance, and recent developments to use them in the treatment of various types of wastewaters. Fast population growth and economic pressure in some developing countries compel the implementation of principles of natural treatment to protect natural environment. The employment of these principles for waste treatment not only helps in environmental cleanup but also conserves biological communities. The systems particularly suit developing countries of the world. We reviewed information on constructed wetlands, vermicomposting, role of mangroves, land treatment systems, soil-aquifer treatment, and finally aquatic systems for waste treatment. Economic cost and energy requirements to operate various kinds of natural treatment systems were also reviewed.

Developing, designing, and testing artificial set of lithologies for soil-aquifer treatment (SAT) systems without soil, using geosynthetic materials

Conventional soil-aquifer treatment (SAT) systems comprise of natural lithological sections up to the depth of zone of saturation or dried aquifers, which through geopurification process recharge the aquifers using domestic or industrial wastewaters. Such SAT systems have low infiltration capacity and frequently face the clogging problems, which causes environment hazards in the local areas. Under this study, three artificial set of lithologies (Lithology I, Lithology II, and Lithology III) were generated without using soil. Each one meter set of lithology was generated within a transparent cylindrical pipe of diameter 15 cm. Each lithology was equipped with nonwoven geotextile and geogrid material at different levels and comprises of coarse aggregate, fine aggregate, coarse sand, medium sand, and fine sand. Use of geotextile material within the artificial lithology shows approximately 8–10 times enhancement in the filtration capacity of the tested lithologies. Municipal wastewater (after primary treatment) was used to test the Lithologies I, II, and III. Between 100–200 l of wastewater was passed through each set of lithology everyday for seven days. Different water quality parameters such as pH, turbidity, electrical conductivity, fluoride, total suspended solids, biological oxygen demand, dissolve oxygen and carbon oxygen demand, chloride, and manganese were analyzed before and after passing through the lithologies everyday. One meter set of artificial lithologies have successfully reduced the concentration of measured water quality parameters between 60 and 93 %, without clogging. Lithology III equipped with superficial fine sand layer and two set of nonwoven geotextile has successfully removed 70–93 % concentration of wastewater. This study aims to demonstrate that a SAT system equipped with geotextile and without soil is more effective then the prevailing SAT systems. Study also proposed designs of SAT systems, which can be formed at unfavorable sites using abundant dry wells in which artificial set of lithologies can be used.

Public consultation on artificial aquifer recharge using treated municipal wastewater

A questionnaire was prepared and distributed among professionals from various fields, in an effort to gather public perception regarding recharge of groundwater using treated municipal wastewater. This was done as part of a study to assess the feasibility of implementing Soil Aquifer Treatment (SAT) using treated municipal wastewater in parts of central India. This paper presents the perception of people toward artificial recharge and determines the primary concerns among members of the public, so that these can be addressed while carrying out pilot studies. This is the first such public survey that has been carried out in India.The questionnaire was sent to approximately 500 people through e-mail and was uploaded on a popular online portal that deals with water and sanitation issues. 194 correctly filled questionnaires were collected, the results of which are presented in this paper. 87 (45%) questionnaires were filled by environmental professionals including members of the research community, teachers and public health and municipal corporation officials. The rest were filled by members of the general public, including 15 students and 48 non-environmental professionals. Out of 194 respondents, 64.4% were in favor of using treated municipal wastewater for artificial recharge of groundwater, 28.4% opposed and 7.2% remained indifferent.This survey revealed that the primary concern among respondents was the effectiveness of wastewater treatment in India, and not the recharge technique itself. More than 50% of those who support SAT expressed uncertainty as to whether secondary effluent from wastewater treatment plants is being treated to a quality suitable for injecting into the aquifer.

Transport and fate of bacteria in SAT system recharged with recycling water

Soil aquifer treatment (SAT) system plays an important role in degrading organic pollutants, removing bacteria, N, P and so on during artificial groundwater recharge with recycling water. In order to discover the possibility for the pathogen going through aerated zone and contaminating groundwater, this paper presents an experiment on the transport and fate of the bacteria (Escherichia coli L.) in SAT system, a packed silt soil column, under saturated conditions. The simulated solution considered the basic control index and maximum limit value of groundwater recharge with recycling water. The concentration of bacteria was 105 Colony-Forming Units L−1 in the secondary discharge standard of wastewater treatment plant effluent. The experiment included two recharging stages (firstly for 288 h and secondly for 528 h) with 264 h drying between them. The results showed that there was no detection of E. coli L., and the electric conductivity, total nitrogen, permanganate index became the same finally between the influent and effluent. The concentration of E. coli L. in the solid phase decreased from up to down of the column. This simulation of recycling water recharge could make people understand the transport and fate of contaminants better, and provided reference to practical projects.

Fluorescence spectroscopic characterization of dissolved organic matter fractions in soils in soil aquifer treatment

This work investigated the effect of soil aquifer treatment (SAT) operation on the fluorescence characteristics of dissolved organic matter (DOM) fractions in soils through laboratory-scale soil columns with a 2-year operation. The resin adsorption technique (with XAD-8 and XAD-4 resins) was employed to characterize the dissolved organic matter in soils into five fractions, i.e., hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N), and hydrophilic fraction (HPI). The synchronous fluorescence spectra revealed the presence of soluble microbial byproduct- and humic acid-like components and polycyclic aromatic compounds in DOM in soils, and SAT operation resulted in the enrichment of these fluorescent materials in all DOM fractions in the surface soil (0-12.5 cm). More importantly, the quantitative method of fluorescence regional integration was used in the analysis of excitation-emission matrix (EEM) spectra of DOM fractions in soils. The cumulative EEM volume (Φ T, n ) results showed that SAT operation led to the enrichment of more fluorescent components in HPO-A and TPI-A, as well as the dominance of less fluorescent components in HPO-N, TPI-N, and HPI in the bottom soil (75-150 cm). Total Φ T, n values, which were calculated as [Formula: see text], suggested an accumulation of fluorescent organic matter in the upper 75 cm of soil as a consequence of SAT operation. The distribution of volumetric fluorescence among five regions (i.e., P i, n ) results revealed that SAT caused the increased content of humic-like fluorophores as well as the decreased content of protein-like fluorophores in both HPO-A and TPI-A in soils.

Degradation of emerging contaminants in reclaimed water through soil aquifer treatment (SAT)

Soil aquifer treatment (SAT) is considered to be an alternative technique able to enhance recharged water quality for aquifer recharge purposes. It allows the reuse of treated wastewater, which usually contains some recalcitrant organic micropollutants such as pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). This study reports the removal capacity for a selection of organic micropollutants during SAT and the characterisation of the recharge system for the interpretation of the data. The experiment was performed in Angerville (France), where the treated wastewater effluent of the wastewater treatment plant (WWTP) is directly infiltrated through an excavated infiltration pond after biological treatment. The system was instrumented by installing piezometers downgradient of the infiltration pond, which were monitored, together with other reference points, and analysed for detailed interpretation. Results on the site characterisation allowed the quantification of the mixing proportion of the recharge water and groundwater and identification of the redox conditions encountered within the aquifer. With respect to the targeted micropollutants, results showed that they exhibited different behaviour during infiltration. Examples of atrazine, gemfibrozil and carbamazepine are discussed as a representation of the most characteristic patterns of organic contaminant fate after recharge.

Soil cultivation for enhanced wastewater infiltration in soil aquifer treatment (SAT)

Summary Soil aquifer treatment is often employed as a tertiary treatment component of reclamation proceeding of wastewater for irrigation in agriculture. Reductions in infiltration rates due to increase in water repellency have been reported to be associated with organic matter (OM) accumulation in the soil (mainly in the top soil layer) as a result of treated wastewater (TWW) infiltration. Our aim was to reduce OM content in soils extensively loaded with TWW. Four model infiltration ponds were built to simulate large infiltration basins: three for TWW infiltration using different application regimes, and the fourth for freshwater (FW) infiltration (control). We examined changes in OM content, hydraulic conductivity (HC) and water repellency in these model ponds as a result of soil plowing. In field experiment, four soil-plowing events were performed. Reduced OM content and water repellency, and increased HC were found in all TWW-applied ponds following each soil plowing. These changes were attributed to OM burial in deeper soil layers elimination of the continuity of the OM based crust, and surface exposure of soil with low OM content. An overall reduction in OM content was found at the end of the experiment in all soil layers as a consequence of plowing. No changes in OM content, water repellency or HC were found in the FW-applied pond as a result of soil plowing.

Environmental Management of Groundwater in Egypt via Artificial Recharge Extending the Practice to Soil Aquifer Treatment (SAT)

The economic development in Egypt and the rapid growth rate in various development sectors are dependent on the availability of water resources. Egypt has turned to use the groundwater to satisfy the growing demand, at the expense of exceeding the safe yield and overexploiting the aquifer systems in some areas such as western Nile Delta and along the desert fringes in the Nile Valley. Shortage of irrigation water sources in Egypt bring out the issue of using non-conventional water resources. As a part from the Environmental Management of Groundwater Resources, Egypt launched a program to examine the feasibility of artificial recharge for the augmentation of groundwater supply. Through this program a detailed study has been carried out for the investigation and potential site selection for carrying out an artificial recharge experiment using treated wastewater. The aquifer artificial recharge by treated sewage water is a new tool can be applied in Egypt for using the sewage water safety compared with the direct use. Through the aquifer soil (unsaturated zone), advanced sewage treatment stage will be added by which most of the biological load will be removed and partially reduction in concentrations of some chemicals can be found. This paper presents the preliminary hydrogeological investigation and tested scenarios for the aquifer storage which used to evaluate the technical environmental, consideration in Abu Rawash farm as a case study. In addition to applying environmental impact assessment (EIA) of artificial recharge experiment to assess the feasibility guidelines for the future recharge projects. Results indicated that artificial recharge for groundwater aquifer using treated wastewater is promising whoever it needs more detailed study to assess the aquifer feature influences the mechanism of recharge with treated wastewater. The health risk due to changes in the physical and chemical conditions prevailing in the aquifer or due to limited adsorption capacities as well as the microorganisms survive and toxic pollutants degradation.

Attenuation of Bulk Organic Matter, Nutrients (N and P), and Pathogen Indicators During Soil Passage: Effect of Temperature and Redox Conditions in Simulated Soil Aquifer Treatment (SAT)

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.

Human Health Risk Assessment of Non-Regulated Xenobiotics in Recycled Water: A Review

ABSTRACT Water suppliers face increased pressure to explain the relative health risks from non-regulated xenobiotics that may be present in recycled water, including pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds. This report reviews their occurrence, fate, and recent human health risk assessments for potable and non-potable water reuse. The most effective advanced treatment for PPCPs is reverse osmosis (RO) followed by advanced oxidation. During soil aquifer treatment, the majority of PPCPs are attenuated relatively quickly (within 100 days), yet some are persistent and can migrate to the underlying groundwater at low concentrations. Recently, several investigations have assessed the potential human health risks associated with xenobiotics in recycled water, focusing on exposure from drinking water (e.g., planned and unplanned indirect potable reuse) and non-potable reuse (e.g., exposure via recreational, occupational, and irrigation-related activities at sites utilizing recycled water). Risk assessments conducted over the last 10 years have found no adverse human health effects or significant risks. Though advanced treatment of wastewater that is discharged or recycled may not be required to protect public health, it may be necessary to prevent potential effects on exposed biota and to address, to some degree, the public's perception of water reuse.

Removal of Estrone (E1), 17β-Estradiol (E2) and 17α-Ethinylestradiol (EE2) During Soil Aquifer Treatment of a Model Wastewater

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.

Biological removal of pharmaceuticals and personal care products during laboratory soil aquifer treatment simulation with different primary substrate concentrations

Pharmaceuticals and personal care products (PPCPs) have been detected in bodies of water worldwide, yet their effects on the environment are not fully understood. Recent toxicity studies suggest that mixtures of PPCPs at low concentrations may be detrimental to exposed organisms, highlighting the need to remove PPCPs from wastewater treatment plant effluent before it is discharged to the environment. In this study, the utility of biofilm-based PPCP removal as a means to prevent environmental PPCP contamination was investigated. The removal of 14 PPCPs, each at an initial concentration of 10 μg/L, was studied in laboratory sand columns inoculated with wastewater treatment plant effluent. The examined PPCPs included biosol, biphenylol, p-chloro-m-cresol, p-chloro-m-xylenol, chlorophene, sodium diclofenac, gabapentin, gemfibrozil, 5-fluorouracil, ibuprofen, ketoprofen, naproxen, triclosan, and valproic acid. Ten of the PPCPs were removed by greater than 95% during column passage, while the four other compounds proved more recalcitrant. The effect of the concentration (either 50 or 1000 μg/L) of an easily degradable primary substrate (acetate) supplied along with the mixture of PPCPs was examined. Most of the tested PPCPs were removed consistently by the biofilms regardless of the concentration of acetate, although the extent of removal for three compounds showed dependence on acetate concentration, and two behaved with no reproducible pattern over time. Biofilm protein measurements indicated that the mixture of PPCPs supplied to columns suppressed biofilm growth, suggesting toxicity of the PPCPs to the biofilm communities. This laboratory-scale experiment suggests that biofilm-based water treatment strategies, such as soil aquifer treatment and slow sand filtration, may be well-suited for the removal of many PPCPs from impacted water.

Functional diversity changes of microbial communities along a soil aquifer for reclaimed water recharge

The physiochemical and functional diversity of soil-attached microorganisms was investigated using a stabilized laboratory-scale soil aquifer treatment (SAT) system. In this system, reclaimed water after ozonation was used as the feed water, and 60% dissolved organic carbon was removed by the unsaturated vadose layer in 0.8days. Soil biomass (volatile solids, phospholipid extraction) and functional diversity significantly decreased from the unsaturated vadose layer to the saturated aquifer, where they maintained the same level. Using principal components analysis based on substrate utilization pattern, the vadose layer soil sample was clearly separated from the saturated layer samples. Exceptionally, the oxidation rates of esters remained stable during SAT, indicating the purification potential on certain recalcitrant organic compounds in the saturated aquifer given an adequate retention time. Correlation analysis revealed that organic carbon was the key limiting factor for microbial biomass and activity, especially for tyrosine-like aromatic proteins and soluble microbial byproduct-like materials.

地下浸透処理における下水処理水中残留医薬品類の消長に関する基礎的検討

わが国で水再生利用を目的とした地下浸透処理を行った場合の，下水処理水中の残留医薬品類に対する除去能を評価するための基礎検討実験を行った．具体的には地下浸透を模した回分式実験により，真砂土を用いた短期間の処理における生分解能と土粒子への収着傾向を評価した．さらに生分解された物質についてその分解生成物の探索を行い，地下浸透処理の物質分解機構に関する知見の収集を図った．その結果，医薬品類に対する除去性には物質により大きな差が見られ，下水処理・浄水処理との適切な連携が必要であることが示された．また，原体の基本骨格を保持した数種の微生物分解生成物が検出され，対象物質原体が減少する一方で新たに非意図的に生成される物質があることを示した．