Application Of Municipal Wastewater Research Articles

Green hydrogen derived from municipal wastewater via bioconversion by attached microalgae onto various sizes of polyurethane foam cubes

In order to mitigate the environmental impacts of fossil fuel consumption and gear up for its depletions over the years, it is essential to explore the transition towards the renewable energy sources. Microalgae are characterized as the primary producers in an ecosystem which can adapt easily and have high growth rate. Indeed, microalgae can produce various biofuels, inclusive of green hydrogen which is touted as the most clean and sustainable option for fossil fuel replacement. Immobilization of microalgae onto polyurethane foam had been employed in the current study to increase the hydrogen yield, while offering an easy harvesting process for potential reusability, and preventing cells’ wash out from cultivation system. Polyurethane foam cubes of four different sizes, namely, 0.5, 0.75, 1 and 2 cm (cubes’ edge lengths), were initially used to immobilize microalgae for 7 days. They were then introduced into municipal wastewater medium to provide alimentation for attached microalgae in performing dark fermentation. The results revealed that the 1 cm cubes’ size could consistently produce high hydrogen volumes of 20 – 21 mL with the COD and ammoniacal nitrogen removal efficiencies being achieved at 70% and 57%, respectively. The smaller sizes than 1 cm cubes failed to sustain its hydrogen yields due to the excessive losses of attached microalgae stemming from the abrasion process when the cubes were fluidizing in the culture medium. The bigger cubes than 1 cm had produced lesser hydrogen due to the limited surface area available to populate attached microalgae. And also due to the diffusion limitation of essential nutrients from culture medium into the cubes to support the metabolic activities of attached microalgae within the cubes. The hydrogen production from 1 cm cubes was also well fitted into the first order kinetics, attaining theR2 = 0.9998 and rate constant of 0.1247±0.0005h-1. Lastly, a statistical model was derived to predict the overall hydrogen yield from attached microalgae onto 1 cm polyurethane foam cubes. This was carried out based on the amount of COD being fermented to produce hydrogen in advocating the application of municipal wastewater as the alimentation for microalgal bioconversion.

Improvement of degraded agricultural soil in an arid zone following short- and long-term treated municipal wastewater application: A case study of Gabes perimeter, Tunisia

This work aimed to study the short, medium, and long-term influences of treated wastewater (WWTP) as a soil irrigation technique on physical, chemical, and microbiological properties. Sampled soil plots were irrigated with WWTP for 1, 7, and 15 years. Rain-fed regime soil has been used as a control. This study was conducted in El Hamma of Gabes (southeast of Tunisia), an arid zone, during the dry season. Three soil profiles at 0–20, 20–40, and 40–60 cm were sampled. Physical and chemical analyzes, including pH, electrical conductivity, total organic carbon, total nitrogen, cation exchange capacity, and active and total CaCO3 were evaluated. Soil microbial biomass C and N were performed according to the fumigation extraction method. Soil microbial contamination was assessed by enumerating total, Fecal Coliforms, E. coli, and Fecal Streptococci with the most probable number (MPN) method and plate medium count. Bacterial and fungal enumeration were evaluated by the plate count agar method. In addition, the DGGE molecular analysis was also assessed in the different soil samples. The obtained physical and chemical evaluation proved that the WWTP irrigation practice improves soil fertility. Microbial biomass C and N increased by increasing the time of WWTP irrigation. In addition, the sanitary quality of the soil is affected by the increase of pathogens. We have observed an increase in microbial biomass as demonstrated by an increase in heterotrophic bacteria and filamentous fungi in the soil irrigated with WWTP compared to the control. Long-term WWTP irrigation has increased the activities of the soil microorganisms and then soil fertility. Meanwhile, the same pathogens and bacteria could pose a serious threat to sanitary soil quality and a limiting factor for the use of WWTP in agriculture areas without tertiary treatment.

Efficient photocatalytic removal of phthalates easily implemented over a bi-functional {001}TiO2 surface

It is stubborn to remove the lowly concentrated phthalic acid esters (PAEs) that usually coexist with other highly concentrated but low-toxic pollutants in municipal sewage. Herein, we report a novel strategy for completely removing the PAEs over a bi-functional {001}TiO2 surface (with highly exposed {001} facet), which not only serve as functional sites to specifically adsorb the target PAEs pollutants, but also contribute to an enhanced oxidation ability. The adsorption behavior of PAEs on {001}TiO2 is analyzed deeply through kinetic experiments combining with in situ ATR-FTIR spectroscopy and theoretical calculations. The results reveal that the adsorption capacities of PAEs on {001}TiO2 are about 4–5 times higher than that on TiO2, both of which follow the pseudo-second-order and Langmuir model. This is mainly attributed to the interfacial Lewis Acid-Base Pair between {001} facet Ti5c sites and CO of PAEs. Benefitting from the specific adsorption capability toward target pollutant and enhanced oxidation ability of {001} facets, nearly 100% of DMP or DEP in simulated wastewater can be eliminated by {001}TiO2 within 2 h illumination, and the relevant degradation rate constants (k) (3.67 h−1 for DMP and 2.19 h−1 for DEP) are 5.73 and 3.08 folds higher than that of pure TiO2, respectively. In the application of municipal wastewater, nearly 76% of DMP and 85% DEP can be eliminated by {001}TiO2 within 2 h illumination, which are nearly 3–6 fold higher than that of pure TiO2.

WASTEWATER IRRIGATION, ITS IMPACT ON ENVIRONMENT AND HEALTH RISK ASSESSMENT IN PERI URBAN AREAS OF PUNJAB PAKISTAN – A REVIEW

Due to water scarcity issues in developing countries, wastewater irrigation has become a viable common practice in majority of the agricultural areas of Pakistan. It has been widely claimed that the use of wastewater for irrigation purpose not only helps in addressing the issues of water scarcity but fulfills the nutritional requirements for the cultivation as well. But the municipal wastewater in urban and peri urban areas of Punjab are carrying excessive pollution loads of untreated industrial wastewater, which is becoming a source of subsurface contamination as well as health hazard, due to carriage of toxic chemicals and heavy metals through the drains, being released from the industries. Industrial areas have equally been spread out all over the province of Punjab, thus the issue of irrigation by using untreated wastewater exists in all the regions of the Punjab. This research work reviews the findings of impact of different significant parameters on soil and groundwater and the uptake of these parameters by the plants and vegetations, along with assessing the health risk of these contaminants on humans after consumption. Based on the review, frame work for the application of municipal wastewater for irrigation purpose in the peri urban areas of Punjab has also been recommended.

Ecological and Hygienic Estimation Precipitation of the Municipal Wastewater Application at the Formation of Secondary Ecosystems in the Mining and Iron Ore Processing Areas

On the basis of Krivoy Rog iron mining ore deposit companies (Ukraine) the complex field studies focused on the fast development of secondary landscapes in the surface of dumps after iron mining were carried out. In order to create the top layer of waste purification from household sewage was carried out sewage clearing facility silt. It is well known that breed dumps are dangerous for the environment, particularly for the surface and ground water. Overnormal concentrations of salt had been found in water samples, taken from the river Inhulets in a zone of influence breed (2.1 MPL), sulfates and carbonates (2.7 MPL), iron (2.1 MPL), chloride (1.7 MPL), magnesium (3.1 MPL). In the wells from nearest villages water is not suitable for drinking purposes and contains total sum of salts – 4.97 MPL, sulfates and carbonates – 5.16 MPL, cadmium – 3.7 MPL, lead – 1.53 MPL. Thus, the toxic heavy metals concentrations (Pb, Cd, Zn, Mn, Cu, Cr, Ni, Fe) in the fish and amphibians, as well as herbaceous plants in these areas did not exceed the permissible levels.Use of clearing facilities sludge aged from 1.5 years and more in the amount 15 kg/m2 did not lead to increased concentration of heavy metals in the top layer of dumps. Total pollution of the soil within six months after application of sludge correspond to the "permissible" level (Zc = 1.61).To assess the suitability of the silt dumps, we proposed list of indicators, which correspond to the chemical and epidemiological safety and classify as "suitable", "conditionally suitable" and "not suitable". We found that optimal conditions for formation of a new soil dumps with ratio of such indicators as "nitrogen: phosphorus: potassium" should be corresponded to the working dose 300 kg/ha by nitrogen amount. This is the maximum amount of mature silt 66.7-70 ton/ha.

Hydrologic Impacts of Municipal Wastewater Irrigation to a Temperate Forest Watershed.

Land application of municipal wastewater to managed forests is an important treatment and water reuse technology used globally, but the hydrological processes of these systems are not well characterized for temperate areas with annual rainfall of 1200 mm or greater. This study evaluated the impact of municipal wastewater irrigation to the local water balance at a 3000-ha land application facility where secondary-treated wastewater is land applied to a mixed hardwood-pine forest over 900 ha. Stable isotopes of hydrogen (H) and oxygen (O), chloride concentrations, and specific conductance were used in combination with hydrometric measurements to estimate the wastewater composition in groundwater, surface water, and at the watershed outlet during dry and wet seasonal periods and during one large rainfall event. Wastewater and water bodies receiving irrigation were found to have significantly higher δH, δO, specific conductance, and chloride concentrations. Using these tracers, a two-component, three-end member geochemical mixing model estimated mean wastewater compositions in the surficial aquifer receiving irrigation from 47 to 73%. Surface water onsite was found to reflect the high wastewater composition in groundwater. Land-applied wastewater contributed an estimated 24% of total streamflow, with the highest wastewater compositions in surface water observed during major storm events and at low-flow conditions. Groundwater and surface water within the watershed were found to have proportionally higher wastewater compositions than expected based on the proportion of irrigation to rainfall received by these areas.

Pharmaceutical occurrence in groundwater and surface waters in forests land-applied with municipal wastewater.

The occurrence and fate of pharmaceutical and personal care products in the environment are of increasing public importance because of their ubiquitous nature and documented effects on wildlife, ecosystems, and potentially humans. One potential, yet undefined, source of entry of pharmaceuticals into the environment is via the land application of municipal wastewater onto permitted lands. The objective of the present study is to determine the extent to which pharmaceuticals are mitigated by or exported from managed tree plantations irrigated with municipal wastewater. A specific focus of the present study is the presence of pharmaceutical compounds in groundwater and surface water discharge. The study site is a municipality that land-applies secondary treated wastewater onto 930 hectares of a 2000-hectare managed hardwood and pine plantation. A suite of 33 pharmaceuticals and steroid hormones was targeted in the analysis, which consisted of monthly grab sampling of groundwater, surface water, and wastewater, followed by concentration and cleanup via solid phase extraction and separation, detection, and quantification via liquid chromatography coupled with tandem mass spectrometry. More than one-half of all compounds detected in irrigated wastewater were not present in groundwater and subsequent surface water. However, antibiotics, nonsteroidal anti-inflammatory drugs, caffeine, and other prescription and over-the-counter drugs remained in groundwater and were transported into surface water at concentrations up to 10 ng/L. These results provide important documentation for pharmaceutical fate and transport in forest systems irrigated with municipal wastewater, a previously undocumented source of environmental entry.

Effect of Subsurface Drip Lateral Depth and Spacing on Grass Yield Using Treated Municipal Wastewater Application

Effect of Subsurface Drip Lateral Depth and Spacing on Grass Yield Using Treated Municipal Wastewater Application

The effect of municipal wastewater irrigation on yield and biomass of canola (Brassica napus L.) and soil chemical properties

The aim of this study was to test if wastewater irrigation can increase fertilizer use efficiency and improve soil fertility without affecting the quality of soils and plants. The present study was carried out in order to investigate the impact of irrigation municipal wastewater on macro nutrient content of soil, biomass and yield of two varieties of canola (Brassica napus L.viz., SLM046 and Ocapi). The studies were done using Entisols sampled to a depth of 0-30 cm from agricultural fields in Boruojerd province (33°54' N, 48°40' W;1620 m above sea level) in Iran. In this experiment, we have used the experimental lysimeters was designed based on the randomized complete block with three municipal wastewater ratio of 100, 50 and 0% (diluted with irrigation water) and four replicates. The results of this experiment showed municipal wastewater irrigation affected significantly soil chemical properties especially in rhizosphere soil and biomass and yield. Application of municipal waste water increased soil salinity, organic matter, exchangeable Na, K, Ca, Mg, plant available phosphorus and decreased soil pH. It can be concluded that municipal wastewater can be used confidently in the short term in agricultural land both as fertilizer source and to increase fertilizer use efficiency for economical aspect.

Effects of 15-year application of municipal wastewater on microbial biomass, fecal pollution indicators, and heavy metals in a Tunisian calcareous soil

Water shortage in most countries of the southern Mediterranean basin has led to the reuse of municipal wastewater for irrigation. Despite numerous advantages for soil fertility and crop productivity, recycling wastewater in the soil also has several ecotoxicological and sanitary problems. To evaluate the chronic soil contamination and the cumulative impact of wastewater, we compared seven plot sites irrigated with treated wastewater 1, 2, 7, 9, 13, and 15 years and one nonirrigated taken as control, and these were sampled for soil analysis. Soil samples were analyzed for pH, electrical conductivity (EC), total Kjeldahl nitrogen (TKN), total organic matter, and total concentrations of Cu, Zn, Fe, Ni, Pb, and Cd. Microbial biomass and enteric bacteria (fecal coliforms and fecal streptococci) were determined in all soil samples. The soil pH values were not consistently affected. Soil salinity, measured as EC, appeared significantly high and proportional to the duration of wastewater irrigation. Also, concentrations of total Ni, Zn, Cu, Pb, and Cd increased significantly (P ≤ 0.05) according to the number of irrigation years but are usually under Tunisian standards. The concentration of heavy metals (Ni, Zn, Cu, Pb, and Cd) showed a significant decrease in the soil profile. The microbial biomass carbon (MBC) is 1.5 times larger in the soil irrigated for 15 years with treated wastewater as compared to the one taken as control. The growth of microorganisms might be explained by the ready source of easily degradable compounds in the oligotrophic soil environment brought about by wastewater irrigation. Soil bacteriological analysis showed that the number of fecal coliforms (FC) and that of fecal streptococci (FS) were affected appreciably (P ≤ 0.05) by the duration of wastewater application (number of years) and by the soil depth (0–20, 20–40, and 40–60 cm). Treated wastewater irrigation led to changes in physicochemical and microbiological soil properties. The magnitude and specificity of these changes significantly correlated with the duration of such practice. It can be concluded, based on these results, that the proper management of wastewater irrigation and periodic monitoring of soil fertility and quality parameters are required to ensure successful, safe, and long-term reuse of wastewater irrigation.

Municipal wastewater application to Short Rotation Coppice of willows – Treatment efficiency and clone response in Estonian case study

Wastewater application to Short Rotation Coppice (SRC) of fast growing trees (willows and poplars) is an attractive alternative to conventional forestry and water purification systems to meet the environmental and renewable energy goals set in European Union (EU). To evaluate the purification efficiency of willow vegetation filter and to describe the response of different commercial willow clones to pre-treated wastewater application, the study was carried out in experimental SRC during last three years of the first five-year-long harvest cycle. Water samples collected from the lysimeters after percolating through the vegetation filter soil (at 40 cm) indicated substantial reduction of pollutants (58% and 70% for total N and P, respectively). The purification efficiency of studied vegetation filter was sufficient to avoid groundwater pollution and meet the legislative limits of Estonian environmental legislation. Wastewater application did not reduce the average plant survival but increased the average number of shoots, plant dry weight (DW) and wood yield per area significantly. The comparison of average shoot DW of clones indicated quite stable growth pattern of different genotypes irrespective of various growing conditions. The average number of shoots of clones 83, 90, 97, Gudrun and Tora was smaller, the shoots were heavier and clones produced more wood than the rest of the studied varieties. Higher planting density or denser irrigation pipe network did not result in substantially higher wood yield. We conclude that willow SRC functioned efficiently as vegetation filter and when combined with growing more productive clones the economically viable yields should be realistic.

Species Trials of Short Rotation Woody Crops on Two Wastewater Application Sites in North Carolina, USA

Forty-two Populus spp. clones, Eucalyptus benthamii, and seven tree species native to North Carolina were evaluated for survival and height growth through the establishment phase at two municipal wastewater application sites. Groundwater was monitored at each site to determine if establishment of the species trials resulted in exceedances of nutrient mitigation requirements. At the Gibson Wastewater Treatment Facility, 26 Populus clones had 100 % survival, with mean height growths ranging between 152 to 260 cm, and basal diameters ranging between 11.4 and 28.8 mm. Green ash, planted in 2011 and 2012, had high survivorship (>95 %) with first year mean height growth of 30 ± 28 cm (2012) and second year mean height growth of 101 ± 52 cm (2011). Basal diameter for green ash was 33.3 ± 12.6 mm. E. benthamii had moderate survivorship (>77 %) and first year mean height growth of 47 ± 27 cm. At the Jacksonville Wastewater Treatment Facility, green ash and bald cypress had high survivorship (>96 %), first year mean height growths of 14 ± 25 cm and 27 ± 16 cm, and basal diameters of 13.1 ± 3.9 mm and 11.6 ± 4.8 mm, respectively. Survivorship for 12 Populus clones ranged from 50 and 94 % with mean first year height growths between 58 to 121 cm, and basal diameters between 6.8 and 12.5 mm. E. benthamii had low survivorship (43 %) with mean first year height growths of 17 ± 17 cm and basal diameters of 12.0 ± 7.7 mm. Groundwater concentrations of NO3 + NO2 and N-NH4 remained below regulatory requirements at both sites with one exceedance in February 2012 in Jacksonville, NC. The results show that some Populus clones are excellent candidates for woody biomass production on municipal wastewater application fields. Native green ash and bald cypress are also good candidates, but these trees may require longer rotations than Populus to achieve similar biomass yields.

Soil DNA evidence for altered microbial diversity after long-term application of municipal wastewater

Water resources constitute a social, agricultural and economic problem in most countries of the southern Mediterranean Basin. Alternative strategies have been developed such as the reuse of municipal wastewater for irrigation in agriculture. Despite numerous advantages for soil fertility and crop productivity, recycling wastewater in soils also has several ecotoxicological and sanitary problems. Few investigations have assessed the risk by evaluating the impact of wastewater irrigation on soil microbes. Here, we report for the first time the short- and long-term effects of treated municipal wastewater irrigation on the density and genetic structure of bacterial and fungal soil communities. Soils from agricultural sites in Tunisia that had been irrigated with wastewater for 4, 8, 16 and 26 years were characterised. Soil physicochemical and microbial characteristics were assessed by sampling at 0–20 and 20–40 cm depth at each site. Quantitative changes in bacterial and fungal communities were measured by indirect counts on synthetic culture media and qualitative modifications were evaluated by using molecular ecology methods: B- and F-ARISA for Bacterial and Fungal Automated Ribosomal Intergenic Spacer Analysis, respectively. These methods allowed genotyping the structure of bacterial and fungal communities from soil DNA extracts. Our results revealed a significant increase in microbial densities related to the duration of irrigation with wastewater. In addition, wastewater irrigation led to changes in the genetic structure of bacterial and fungal communities, the magnitude and specificity of these changes being significantly correlated with the duration of such irrigation. These results show that wastewater management schemes have a major effect on indigenous microbial abundance and composition in soils that could be related to the recurrent inputs of organic compounds and mineral/metallic elements. In an agro-ecological context, irrigation with municipal wastewater represents an impacting practice that now needs to be evaluated more fully in terms of ecosystem services for sustainable agriculture.

Leaching potential of nonsteroidal anti‐inflammatory drugs in soils

Nonsteroidal anti-inflammatory drugs (NSAIDs) in soils resulting from application of municipal wastewater or biosolids may migrate through soils intact or be transformed and reach groundwater. In the present study, the leaching potential of four NSAIDs (ibuprofen, naproxen, ketoprofen, and diclofenac sodium) in three U.S. cropland soils was evaluated, and the effect of CaCl(2) solution (as an index of salinity), dissolved organic matter (DOM), and polyacrylamide (PAM) amendment was investigated. The soils were spiked with selected NSAIDs, incubated for 24 h followed by 7-d storage in glass flasks, and then packed into stainless steel columns and leached with deionized water (DIW), 10 mM CaCl(2), DOM (DOC 34 mg/L), and PAM solution (1.0 mg/L) by gravity. Initial concentrations of ibuprofen, naproxen, ketoprofen, and diclofenac sodium in the three packed soils were 1.93 to 2.07, 1.74 to 2.27, 1.79 to 2.16, and 1.99 to 2.13 mg/kg, respectively. Maximum concentrations of the above NSAIDs in column effluents were 1.23, 0.92, 0.69, and 1.12 mg/L, respectively, when the soil was leached with 10 pore volumes of water, which occupied 17.4, 11.1, 9.6, and 15.2% of the total chemicals in each soil column. Dissolved organic matter or PAM solution did not facilitate the NSAIDs release from soils. The CaCl(2) solution, however, reduced the amounts of NSAIDs leached from all three soils. Leaching of NSAIDs differed among the three tested soils. The results suggest that the leaching of NSAIDs through soil to water is significant, and the mobility of NSAIDs in soil is related to their chemicals' characteristics (such as pK(a) values) and soil properties (such as soil organic matter and clay content). Amending soil with DOM or PAM does not significantly affect the leaching behavior of NSAIDs in soil, whereas increasing the salinity of the irrigation water may decrease the extent of contamination of groundwater posed by NSAIDs.

Assessment of Reclaimed Municipal Wastewater Application on Rice Cultivation

Field research was carried out to assess the effects of the application of reclaimed municipal wastewater on rice cultivation in Thessaloniki, Greece during a 2-year period (1999-2000). Effects on production cost, soil composition, and health risk were examined. A randomized complete block design was used for the paddy field with three treatments and four replicates. The treatments were (1) river irrigation water with N-P fertilization, (2) reclaimed wastewater irrigation with surface N fertilization, and (3) reclaimed wastewater irrigation without fertilization. The results showed that the total production cost decreased 8.8% and 11.9% by applying the second and third treatments, respectively, compared to the first treatment, without significant differences in the agronomic and rice quality traits. Soil composition showed discrepancies between the 2 years and the three treatments, whereas the pathogens of the reclaimed wastewater and rice tissues posed a low human risk when taking the needed precautions.

Simulation of Nitrogen Transport in Soil Under Municipal Wastewater Application Using LEACHN1

Abstract: To reduce the risk of surface and ground water pollution from nitrate, and in so doing improve the quality of receiving waters, better management options for land application of wastewater must be explored. In order to determine proper and environmentally safe wastewater land application methods, different application scenarios were simulated in this study to determine the fate and transport of nitrogen in sand‐filled field lysimeters. The Leaching Estimation and CHemistry Model for Nutrients (LEACHN) model was used to assess alternative wastewater land application scenarios: applications of low‐, medium‐, or high‐N concentration wastewaters, at different rates (0.06, 0.19, 0.31, or 0.6 m3/m2/day), under continuous or intermittent application. In the simulations, the NO3−‐N levels decreased in the leachate with an increase in wastewater application rates, due to enhanced denitrification in the upper anoxic zone of the soil generated under high flow rates. With low‐N concentrated wastewater, under all tested flow rates, the NO3−‐N levels in the leachate were below the permissible limit. When medium‐N wastewater was applied, the NO3−‐N level in leachate from the highest flow rate was below the permissible limit. Therefore, wastewater with low‐N concentrations, about 10 and 0.5 mg/l NO3−‐N and NH4+‐N, may be continuously applied to soil at all tested flow rates, with minimal nitrate pollution problems. Medium and high‐N concentrated wastewaters increased nitrate levels in the leachate, as compared to their levels in the low‐N concentrated wastewater. It appears that while low‐N wastewater can be safely applied to land without much nitrate leaching problems, the application of medium and high‐N wastewater could pose nitrate pollution problems. The simulation with intermittent application of low‐, medium‐, and high‐N concentrated wastewater at different rates showed a 51‐89% greater reduction in NO3−‐N levels in the leachate, than for continuous application under all tested wastewater N‐levels and flow rates. Also, the levels of NO3−‐N in their leachates were below the permissible limit. Therefore, wastewater with high levels of nitrogenous compounds (up to 54 NO3‐N mg/l) could be treated through an intermittent application to land.

LONG-TERM EFFECTS OF MUNICIPAL SEWAGE ON SOILS AND PASTURES

ABSTRACT Land application of municipal wastewater is widely practised worldwide as a means of treating wastes and obtaining a benefit from the water and nutrients by growing pastures, trees, and sometimes edible crops such as vegetables, fruit and fibre, etc. Irrigation of pastures by treated and untreated sewage near Melbourne, Australia, for more than a century has increased heavy metals concentrations in the soil, but appears not to have increased their concentrations in the herbage and in animal tissues of animals grazed on these pastures. There seem to be sound reasons why this practice may be sustainable.

First-year Growth Response of Ornamental Trees to Municipal Wastewater Application

The U.S.–Mexico border region has experienced rapid population growth in the past 30 years, resulting in natural resource degradation and declining public health. Many U.S.–Mexico border municipalities have inadequate systems for dealing with their waste. A major concern is the threat posed by water pollution, particularly that caused by minimally treated and improperly disposed human wastes. Border wastewater systems need to reduce contaminants, as well as safely recycle nutrients. Existing technology supports the land application of wastewater to tree production for low-cost, low-technology wastewater purification. Chemical analyses of the wastewater has shown that the water possesses an EC of 2.7 to 3.0 dS/m and an SAR of 6 to 7 indicating both high total salinity and sodicity that are potentially damaging to most woody horticultural crops. This project, located in Ojinaga, Mexico, assesses first-year growth characteristics and survival of three fast-growing trees useful for pulpwood production, Eucalyptus camaldulensis (three clones), hybrid Populus spp. (three clones), and Robinia pseudocacia (seedling propagated) following application with saline wastewater. Significant variation in trunk cross-sectional area was exhibited among clones. Eucalyptus clones showing the greatest increase in trunk area growth also exhibited ≈80% dieback during the winter months. Preliminary data indicated that one of the Populus clones may be the best option for effective wastewater treatment and economic sustainability through the sale of pulpwood for Ojinaga and other U.S.–Mexico border communities.

Irrigation with reclaimed municipal wastewater

Land application of municipal wastewater is a well established practice in many arid and semiarid countries of the world. Although irrigation with municipal wastewater is in itself an effective form of wastewater treatment, some degree of treatment must be provided to 1) protect public health, 2) prevent nuisance conditions, and 3) prevent damage to crops, soils, and ground-water. Factors affecting irrigation with reclaimed wastewater include irrigation water quality and public health and regulatory considerations.

Fate of trace organics during land application of municipal wastewater

Recent developments in analytical techniques have provided a better characterization of trace organics in municipal wastewater and have increased public awareness concerning potential health risks of renovated waters. Although renovation of wastewater by land application is an economical alternative to conventional treatment processes and can provide comparable treatment with respect to standard water quality parameters, there have been few quantitative studies on the fate of trace organics in these systems. This review evaluates the potential for trace organic removal by abiotic and biotic processes during rapid infiltration, irrigation, and overland flow of municipal wastewater. Special emphasis is directed towards rapid infiltration because this method of land application has the greatest potential for affecting associated groundwaters. Many trace organics which are present in municipal wastewater are transported to groundwater during rapid infiltration, although concentrations of most compounds are at...