Tertiary Treated Sewage Effluent Research Articles

Innovative stimuli-responsive membrane MSF brine rejection dilution by tertiary treated sewage effluent

In this study, treated wastewater and Multi-Stage Flash (MSF) brine were integrated into the Forward Osmosis (FO) system using pressure stimuli-responsive Nanofiltration (PSRNF) membranes to dilute magnesium, calcium, and sulfate MSF plant brine reject. The deposition of magnesium sulfate and calcium sulfate in the heat exchanger is one of the main issues affecting the performance and efficiency of MSF thermal desalination plants. Reducing the concentration of the divalent ions can minimize scale formation and deposition to a level that allows the MSF plant to operate at high top brine temperature (TBT) and without scale problems. The PSRNF membranes were chosen in the FO process because of their high water permeability, rejection of divalent and monovalent ions, small structure parameter (S), and inexpensiveness compared to commercial FO membranes. Three PSRNF membranes were tested in the FO process with the feed solution facing the active membrane layer to avoid active layer delamination. Although the PSRNF membrane exhibited negligible water flux at 0 bar, it increased when a 2–4 bar was applied to the feed solution. The wastewater temperature was set at 25 °C while 40 °C was the brine operational temperature to mimic the field situation. A maximum average water flux of 39.5 L/m2h was recorded at 4 bar feed pressure when the PSRNF membrane was used for the brine dilution, achieving up to 42% divalent ions dilution at 0.02 kWh/m3 specific power consumption. The average water flux in the PRSNF membrane was 35% higher than that in the commercial TFC FO membrane. Notably, the PSRNF membrane is ten times cheaper than commercial FO membranes. Notably, the PSRNF membrane is ten times cheaper than commercial FO membranes, achieving substantial cost reductions and pioneering advancements in FO purification technology.

The impact of replacing groundwater by treated sewage effluent on the irrigation requirements of Al Ghaf (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi) forests in the hyper-arid deserts of Abu Dhabi

The arid forests of Abu Dhabi are valuable but they require irrigating. Currently groundwater (GW) is the source of this water, but these subterranean reserves are being over-exploited. Law No 5 of 2016 on the regulation of GW has been passed by the Government of Abu Dhabi to reduce GW abstraction. Abu Dhabi has a supply of tertiary-treated sewage effluent (TSE) that could be used as an alternative for irrigation. We set up experiments near Madinat Zayed in the Al Dhafra region of Abu Dhabi on two arid-forest species: Al Ghaf (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi). The trees were planted at 8 m x 8 m spacing. The TSE is significantly ‘sweeter’ than GW, as its electrical conductivity is < 1 dS m−1, whereas GW is 8–10 dS m−1. The GW in this region is very high in nitrates (38.4 ± 9.2 mg-NO3 L−1), and this was not significantly different from the TSE (53.7 ± 11.8 mg-NO3 L−1). We monitored the actual tree water-use (ETc, L h−1) via heat-pulse devices in both the GW and TSE-irrigated trees. We quantified the differences in the ETc patterns for both the GW and TSE-irrigated trees of both species over 3 years. Both species showed positive growth-responses to TSE, relative to the GW, and we consider this to be due to the lower electrical conductivity of the TSE water. Because of this growth response the ETc of the TSE by the Ghaf trees was, on annual average 17% higher than GW, and for the Sidr it was 39%. Our results were corroborated by leaf conductance and leaf-area inferences. But for TSE there is no need for a salt-leaching fraction. Furthermore, to achieve the same tree-health outcome as with the GW, even less TSE need be applied. Irrigation requirements for TSE were at least 25% less than for GW.

The Effect of Tertiary Treated Sewage Effluent on Activity of major Piercing-Sucking Mouth-Parts Insects and their Natural Enemies on Alfalfa Crop

This study was conducted during the period April 2009 to March 2010 in the Northern Governorate, Kingdom of Bahrain, to study the effect of treated sewage water on major alfalfa pests (aphids, leafhopper and plant bugs) and their natural enemies. The study was conducted on six farms, three irrigated by groundwater in the villages of Karranah, Jannusan and Jasra and three irrigated with treated sewage effluent in the villages of Dumistan, Elsahala and Abu Saiba. Insect samples were collected every ten days from five replicates using the standard sweeping net procedure to estimate the numbers of the above insects and their natural enemies. Pitfall traps were used to collect soft dwelling natural enemies. The results showed that irrigating alfalfa with treated sewage water led to a significant increase in population density of aphids and that the groundwater used for irrigation has led to a significant increase in the number of leafhoppers and plant bugs. As for natural enemies, Geocorissp, Dereaocorispallns were significantly increased in alfalfa plants irrigated by ground water, while Coccinella beetles significantly increased in numbers in alfalfa irrigated with treated sewage water Damselbug, aphids lions, ground beetle, tiger beetles, earwigs were not significantly affected by the type of water used. Regarding the seasonal activity of insects, leafhoppers, aphids,and plant bugs, results showed that the highest density of aphids was occurred during the second and third week of December and first week of January, leafhoppers in the second week of December and third week of February, and Plant bug in the second week of October. The activity of seasonal natural enemies had registered the highest density of Geocorissp during the first and third weeks of August. Coccinella beetles showed highest density during the second week of March, while Damselbugs highest density was noted in the fourth week of December and the first week of January. Aphid lions were most active during the fourth week of December and second week of February, whereas the predator Dereaocoris pallens was active during the third week of May and first week of July and ground beetles active during the first weekof May and the fourth week of July through first week of August. Cutting of alfalfa fields more frequent in activity period is a suggested tactic for the management of this pest, as IPM programs designed by the seasonal activity of the pest.

Removal of iopamidol, an iodinated X-ray contrast medium, by zero-valent aluminum-activated H2O2 and S2O82−

Activation of H2O2 (HP) and S2O82− (PS) with zero valent aluminum (ZVA, 1g/L) nanoparticles was investigated for the treatment of the X-ray contrast medium and micropollutant iopamidol (IOPA; C17H22I3N3O8; ≈777g/mol) at pH 3. IOPA (2.6μM) degradation was followed in different water matrices (distilled water, tap water, raw surface water and tertiary treated sewage effluent). Both oxidants could be activated with ZVA resulting in a dramatic enhancement of IOPA degradation due to accelerated hydroxyl and sulfate radical formation. The ZVA/PS (0.5mM) treatment was more effective than ZVA/HP (0.25mM) oxidation resulting in 95% IOPA removal after 120min. IOPA and dissolved organic carbon (DOC) abatements were inhibited when IOPA was treated in real water and wastewater. After 120min treatment, IOPA removals decreased from 95% (PS/ZVA) and 41% (HP/ZVA) in distilled water to 29% (PS/ZVA) and 13% (HP/ZVA) in surface water, respectively. IOPA could not be removed with the PS/ZVA process in treated sewage, although DOC removal was still substantial (28%). For the HP/ZVA combination, 24% DOC accompanied with 20% IOPA removal was achieved after 120min in the same wastewater sample. Changes in acute toxicity were followed during PS/ZVA treatment of IOPA in distilled and surface water. These results exhibited a fluctuating trend depending on the sensitivity of the test organism (Vibrio fischeri and Pseudokirchneriella subcapitata) and water matrix. A genotoxic activity analysis was also conducted and the UmuChromo assay indicated that the original and treated IOPA solutions were not genotoxic but cytotoxic. The potentials and differences of PS/ZVA and HP/ZVA treatment of an iodinated contrast medium could be demonstrated in this study.

Soil properties and carbon stocks in a grey Vertosol irrigated with treated sewage effluent

Treated sewage effluent may contain large amounts of nitrogen and phosphorus, and moderate to high amounts of salts. With good management, it can be used as a source of irrigation water and nutrients for a range of crops and soils under different climatic conditions and irrigation systems. However, there are few long-term studies of irrigation with treated sewage effluent in swelling soils such as Vertosols. This study was established in 2000 on a cotton farm near Narrabri, north-western New South Wales, to assess long-term (14-year) changes in soil salinity, sodicity and carbon storage in a self-mulching, medium-fine, grey Vertosol under conservation farming and furrow-irrigated with tertiary-treated sewage effluent and stored rainfall runoff. Experimental treatments in 2000–02 were gypsum applied at a rate of 2.5t/ha in June 2000 and an untreated control. In 2003–13, the gypsum-treated plots received a single pass with a combined AerWay cultivator and sweeps to ~0.15m depth before sowing cotton; in the control plots, wheat stubble was undisturbed. By retaining significant amounts of crop residues on the soil surface, both practices are recognised as conservation farming methods. Parameters for water sampled from the head-ditch during each irrigation included electrical conductivity (ECw), pHw, concentrations of cations potassium (K+), calcium (Ca2+), magnesium (Mg2+) and sodium (Na+), and sodium adsorption ratio (SAR). Parameters for soil sampled to 0.6m depth before sowing cotton were pH (0.01M CaCl2), salinity (EC of 1:5 soil:water suspension), bulk density, soil organic carbon (SOC), exchangeable Ca, Mg, K and Na, exchangeable sodium percentage (ESP) and electrochemical stability index (ESI). SOC storage (‘stocks’) in any one depth was estimated as the product of bulk density, sampling depth interval and SOC concentration. Management system had little or no effect on cotton lint yields and the soil properties measured. Major changes in soil properties were driven by a combination of irrigation water quality and seasonal variations in weather. The cultivated treatment did not degrade soil quality compared with the control and may be an option to control herbicide-resistant weeds or volunteer Roundup-Ready cotton. Irrigation water was alkaline (average pHw 8.9), moderately saline (average ECw 1.0dS/m) and potentially highly dispersive (average SAR 12.1). Long-term irrigation with tertiary-treated sewage effluent resulted in sodification (ESP &gt; 6) at all depths, alkalinisation at 0–0.10 and 0.30–0.60m, and accumulation in the surface 0.10m of Ca and K. Average ESP at 0–0.6m depth increased from 3.8 during 2000 to 13.2 during 2013. Sodification occurred within a few years of applying the effluent. Exchangeable Ca at 0–0.10m depth increased from 19cmolc/kg during 2000 to 22cmolc/kg during 2013, and exchangeable K from 1.5cmolc/kg during 2000 to 2.1cmolc/kg during 2013. Drought conditions caused an increase in salt accumulation, alleviated by a subsequent period of heavy rainfall and flooding. The reduction in salinity was accompanied by a fall in exchangeable Mg concentrations. Salinity and exchangeable Mg concentration were strongly influenced by interactions between seasonal rainfall (i.e. floods and drought) and the quality of the effluent, whereas ESP and exchangeable K concentration were not affected by variations in seasonal rainfall. SOC stocks declined until the flooding events but increased thereafter.

Effects of Wetland Water Source on a Population of the Australian Eastern Long-Necked Turtle Chelodina longicollis

This study investigates the impacts on the Australian native eastern long-necked turtle Chelodina longicollis of wetland waters derived from (1) precipitation and groundwater flow and wetlands also supplemented with (2) irrigation runoff from agricultural lands, (3) tertiary-treated sewage effluent and (4) harvested stormwater. Influences of water quality parameters on population attributes of the turtle population are considered. A total of 951 C. longicollis were captured in a mark-recapture study over 8 months. Overall, a female sex ratio bias was observed, and a larger number of smaller turtles were found in wetlands not contaminated by recycled tertiary-treated effluent. Dissolved oxygen, temperature, surface area and emergent vegetation had the greatest impact on turtle population structure. The lower the dissolved oxygen, the smaller the surface area of the wetland, and the higher the percentage of emergent vegetation, the greater the number of juveniles present. Water quality parameters which would be detrimental to fish predators appear to provide a ‘safe haven’ for juvenile turtles at the most vulnerable life stage of turtles.

RO membrane cleaning using microbubbles at 6,800 m3/d wastewater RO plant in UAE

It is well known that any fouling of the membrane surface has a dramatic effect on energy consumption and plant efficiency; this is particularly true for waste water reverse osmosis (RO) plants due to the higher fouling rate. Such fouling can be very difficult to clean using commodity chemicals or even speciality chemicals. This paper explores the use of a novel cleaning process designed to increase the efficiency of membrane cleaning using microbubbles. The microbubbles were created by both a physical and chemical process, which circulate in the cleaning solution increasing turbulence at the membrane surface. These bubbles create shear forces which agitate and dislodge the foulant giving greater removal in a reduced time period. In order to demonstrate that there was no damage to the membrane surface or element using this cleaning method with microbubbles, we selected a number of 8″ membranes from the major membrane manufacturers and performed repeat cleans over a 12 month period. Membranes were autopsied to analyse presence of damage, flux and salt rejection performance, results showed that no damage was caused by using this method. These compatibility results were presented in papers at IDA Tianjin 2013. This paper explains how the multiple cleaning mechanisms (both physical and chemical) help remove foulants and restore performance at a tertiary treated sewage effluent treatment plant producing high quality water for reuse. The 6,800 m3/d plant treats conventional activated sludge with microfiltration and RO. Cleans were conducted every 2 or 3 months due to reduced flows and high differential pressures. The new cleaning method using microbubbles with specially formulated cleaning compound cleaners demonstrated that the plant could be cleaned more efficiently and in a shorter timescale than using conventional cleaners.

Effects of effluent contamination of wetlands on population level changes inGambusia holbrooki

While presence/absence of endocrine disruption has been widely observed within polluted wetlands, relatively few data have addressed population level changes for any species. This paper investigated the effects of endocrine disruption on the phenotypic sex ratio, size structure, biomass, and density of Gambusia holbrooki populations in wetlands used for storage of 1) tertiary treated sewage effluent; 2) urban stormwater runoff; and 3) wetlands without effluent supplementation (control wetlands). Those wetlands that had previously been determined to have endocrine disruption effects on G. holbrooki had lower density and biomass of fish than other wetlands. In contrast, the pattern of variation in the average length and phenotypic sex ratio of fish was not consistent with the effects of endocrine disruption.

Apparent Rapid Loss of Endocrine Disruptors from Wetlands Used to Store Either Tertiary Treated Sewage Effluent or Stormwater Runoff

The disruption of endocrine systems due to environmental contaminants potentially impacts on the developmental, behavioural, regulatory and reproductive systems of animals. A major source of exposure of animals (terrestrial and aquatic) to endocrine-disrupting compounds is through contact with contaminated surface waters contaminated with sewage effluent and/or stormwater discharge. We studied the response to endocrine-disrupting compounds of Gambusia holbrooki mosquito fish resident of wetlands that were used for the storage of either treated sewage effluent or stormwater runoff. We found that fish from wetlands that received polluted waters directly from the source (treated sewage effluent or stormwater runoff) demonstrated a morphological response consistent with endocrine disruption. In contrast, fish in the second in the series of wetlands that housed treated sewage effluent did not show evidence of such response. However, those from the second in the series of stormwater receiving wetlands did display a morphological response, although it could be considered milder than was observed in fish from the first in this effluent stream. Fish were also smaller in the wetland that received sewage effluent directly from the sewage treatment plant than elsewhere. Although the differences were not statistically significant, the average size of fish in the first in the series of stormwater wetlands were also small and second only to those in the first sewage effluent wetland.

Viability of multiple antibiotic resistant bacteria in distribution lines of treated sewage effluent used for irrigation

Viability of multiple antibiotic resistant bacteria (MARB) in tertiary treated sewage effluent (TTSE) used for irrigation, was investigated at the Sultan Qaboos University sewage treatment plant (STP). This water recycle system is used here as a model for the systems commonly used throughout Oman and the Gulf region. Samples of TTSE were collected weekly from four sites, 1.5 km from each other. Chlorine levels declined gradually at the three sites with increasing distance from the STP. Viable bacteria, coliforms and nitrate concentrations increased significantly while biological oxygen demand (BOD) declined after STP chlorination. Mean values of turbidity changed slightly. Trace elements values were insignificant. A total of 336 bacteria from 8 genera revealed that the dominant isolates were Enterobacter spp., Pseudomonas spp., and Aeromonas spp. Among the isolates 59.8% were multiply resistant to several antibiotics. Resistance was higher to ampicillin followed by sulphamethoxazole, carbenicillin, streptomycine and minocycline. Frequency of resistance to the 14 antibiotics varied among the isolates. The present system related to the viability of MARB in TTSE used for irrigation may have serious implications for public health and wildlife. Results of this investigation will be of value in modifying current STPs systems and thus avoiding serious health issues.

Characterization of the Ezousas aquifer of SW Cyprus for storage–recovery purposes using treated sewage effluent

Ahydrogeological characterization of the Ezousas alluvial aquifer, located in SW Cyprus, has been conducted to assess its suitability for groundwater recharge with 5 Mm 3 a −1 of chlorinated disinfected tertiary treated sewage effluent from the Paphos Municipality Wastewater Treatment Plant. We present results from a 3 year field study conducted to establish the regional groundwater regime and to define the aquifer hydrology. New drillings at selected locations were made to provide reliable information about the aquifer dimensions and boundaries. Pumping and constant-head permeability tests were used to estimate the key hydraulic properties of the aquifer system. The storage capacity was assessed to be 4.2 Mm 3 . The bedrock of the aquifer, in its approach to the sea, was found to be some 40 m below sea level, thus indicating the potential for seawater intrusion. A monitoring programme consisting of recording piezometric heads and electrical conductivities was used to observe the position of the seawater–freshwater interface, so that rates of abstraction and recharge could be determined, to maintain a stable interface. The quality of the treated sewage effluent, and of native and abstracted groundwater, was continuously assessed in terms of salinity, heavy metals, persistent organic compounds and microbiota, to optimize the quality of the downstream groundwater used for local irrigation.

Changes in soil properties of an eastern Australian vertisol irrigated with treated sewage effluent following gypsum application

AbstractHistorically many towns in inland Australia disposed of their treated sewage by pumping into local rivers. This is no longer a feasible proposition. Alternatives to river pumping include irrigation and/or aquaculture. As treated sewage effluent may contain large amounts of nitrogen, phosphorus and sodium salts, if not managed carefully, soil salinity, sodicity and nutrient accumulation could increase. The objective of this study was to evaluate if gypsum application had any effect on soil‐quality changes in a Vertisol due to irrigating a cotton–wheat rotation with tertiary treated sewage effluent. The treatments were application of 2·5 t ha−1 of gypsum in June 2000 before commencing irrigation and an untreated control. Annually, between June 2000 and April 2004, irrigation water quality and soil changes in nitrate‐N, EC1:5, pH, organic carbon, Cl, dispersion index, and exchangeable cations to a depth of 1·8 m were measured and deep drainage inferred with the chloride mass balance method. Cotton lint yield and fibre characteristics were also evaluated.Irrigation with treated sewage effluent increased exchangeable Na in all depths, and exchangeable Ca and K in the clayey‐textured surface 0·6 m, but decreased exchangeable Ca and K, and SOC in the coarser clay‐loam‐textured depths &gt; 0·6 m. Nitrate‐N leaching, associated with deep drainage had occurred, as the crops had not used all the N in irrigation water. Gypsum application decreased exchangeable Ca, increased dispersion and during the 2003–2004 season deep drainage, but had no effect on salinity, sodicity or pH. Application of commercial gypsum at sub‐optimal rates with sodium‐rich irrigation water is, therefore, unlikely to improve soil properties. Stubble incorporation before sowing cotton in 2003 appears to have mobilized gypsum applied during 2000. Gypsum application reduced cotton lint yield and fibre quality during 2003–2004. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Carbon and nitrogen stable isotope analysis of three types of oyster tissue in an impacted estuary

The stable isotope ratios of carbon ( δ 13C) and nitrogen ( δ 15N) of the muscle, ctenidia and viscera of the Sydney rock oyster, Saccostrea glomerata, showed the dilution and assimilation of tertiary treated sewage along an estuarine gradient. The enriched 15N values of oyster ctenidia and viscera from within 50 m of the sewage outfall indicated the use of 15N-enriched tertiary treated sewage effluent (16 ± 2.3‰) as a nutrient source. The effect of sewage nitrogen on oyster δ 15N was localised, with oysters 5 km upstream and downstream of the outfall not significantly enriched. Viscera δ 15N was most sensitive to sewage nutrients and δ 13C significantly defined an ocean-to-estuarine gradient. High variance in isotope ratios of viscera compromised its use as an indicator of anthropogenic nutrients, and this also reduced the utility of whole-body stable isotope ratios. Ctenidia was the most useful indicator tissue of sewage discharge at the scale of this study, being consistently and significantly enriched in δ 15N close to the sewage outfall and δ 13C clearly defined an estuarine gradient with less internal variability than viscera. Muscle δ 15N was least sensitive to sewage effluent and showed the least variability, making it more suited to investigations of anthropogenic nutrient enrichment over larger spatio-temporal scales.

Use of Rhodamine-WT Dye to Map Effluent Mixing Zones in Lake Dillon, Summit County, Colorado

ABSTRACT The Breckenridge Sanitation District discharges tertiary-treated sewage effluent into Lake Dillon, Colorado, a major water supply reservoir for Denver. The effluent plume was mapped using rhodamine-WT dye during ice-covered and open-water conditions and compared to a criterion issued in a U.S. Environmental Protection Agency policy statement regarding mixing-zone dilution. Rhodamine-WT dye was used as a tracer and was injected directly into the sewage effluent at the outlet of the treatment plant. Dye concentrations were determined using fluorometric analysis. Dye-concentration isolines were determined by interpolation of a rectangular sampling grid. At all sampling locations, plateau dye concentrations were reached within 48 hours after injection began. Results indicated that the Breckenridge Sanitation District's effluent mixing zone extended 158.5 m (520 ft) into the lake during ice-covered conditions on March 15, 1995 (the date of maximum effluent discharge during the study period) and extended 64 m (210 ft) during open-water conditions on September 13, 1995. The EPA criterion for lakes specifies that the maximum allowable length of a mixing zone not exceed 61-m (200 ft).

Interpreting Negative Virus Results from Highly Treated Water

Highly treated waters often contain viruses at concentration levels too low to detect. This paper describes a method for drawing inferences about the concentration of viruses in treated water when very few or none are detected in collected samples. The approach uses a volume-varying version of the negative binomial distribution to construct one-sided confidence intervals about the mean virus concentration. Information on the presence of viruses prior to treatment (i.e., when densities are high enough to measure) is used to estimate parameters for the model. Samples are provided based on measurements from three southern California wastewater-treatment plants. Based on 93,679 L of tertiary treated sewage effluent, confidence intervals for virus concentrations for Pomona, Calif., ranged from 0 to 2.68s˙10−5 plaque forming units (PFU) per liter at the 50% confidence level to 0 to 5.83s˙10−4 PFU/L at the 95% confidence level. These values are considerably above the risk-based public health goal that is being u...

Irrigating with municipal sewage effluent in a rural environment

Abstract Between 1968 and 1988, tertiary treated sewage effluent from the South Lake Tahoe, California area was pumped from the Tahoe basin, stored in a multi‐use recreation reservoir in a neighboring county, and utilized as agricultural irrigant in that county. A comprehensive monitoring program for surface and groundwater in the irrigation area was not implemented until 1980. The holding reservoir repeatedly proved of inadequate size, resulting in spills to an adjacent creek or the use of irrigant at sub‐optimum times. The number of acres available for effluent irrigation decreased substantially during the study period. The amount of effluent irrigant used per acre was significantly higher than the original, anticipated application rates, resulting in demonstrable impacts on surface and groundwater. These impacts, while of no immediate public health concern, were not an intended outcome of the project and were substantially avoidable with better planning. In this rural, near‐pristine environment, all bu...

Significance of Specific Bacterial Pathogens in the Assessment of Polluted Receiving Waters of Sydney, Australia

The impact of primary sewage released from Sydney's ocean outfalls and chlorinated tertiary treated sewage effluent discharged into Sydney's main river system (Hawkesbury-Nepean) have been studied for faecal microorganisms over two years. Faecal indicator bacteria and a range of potential bacterial pathogens (Aeromonas spp., Campylobacters, Pseudomonas aeruginosa, Staphylococcus aureus and salmonellae) were also cultured. Diverting primary-treated sewage from cliff edge release to deepwater (80m) ocean release some 3 km offshore resulted in significant reductions in all bacterial groups examined, with spores of Clostridium perfringens (C.p) being the most sensitive indicator of water quality improvement. In contrast, contamination of inshore sediments has not markedly declined. Campylobacters were not isolated from effluents or seawater, and numbers of S. aureus and P. aeruginosa were very low if detected. Inland river waters were dominated by motile aeromonads, and along with C.p were the most resistant organisms to chlorination following tertiary sewage treatment. However, aeromonads appeared to grow throughout the river system. Campylobacters were associated with areas of agricultural input whereas salmonellae appeared to be associated with significant urban sewage input. Of the indicator bacteria, C.p correlated best with salmonellae, while viruses correlated poorly with the bacterial groups examined. Further work is required to identify possible sources of virulent aeromonads, Campylobacters and salmonellae.

Feasibility of Recharging Treated Sewage Effluent into a Deep Sandstone Aquifera

ABSTRACTArtificial recharge with tertiary treated sewage effluent has been suggested as one remedial measure for projected ground‐water deficits in the Chicago region. A deep sandstone aquifer, an important source of ground water in the region, offers the best opportunity for artificial recharge. Recharge will be through wells since the aquifer is deeply buried. Expected problems in maintaining well injection capacity were studied by recharging treated effluent through formation cores of the sandstone. Some success was had in maintaining recharge rates at constant heads for several days.