Reuse Of Treated Wastewater Research Articles

INNOVATIONS IN IRRIGATION SYSTEMS IN AFRICA†

INNOVATIONS IN IRRIGATION SYSTEMS IN AFRICA^†

Heavy metal accumulation and changes in soil enzymes activities and bacterial functional diversity under long-term treated wastewater irrigation in East Central region of Tunisia (Monastir governorate)

Climate change and population growth generates a decrease in water availability around the world which can compromise the maintenance of sustainable agriculture. Thus, treated wastewater (TWW) became an alternative to minimize water shortage. However, this may indirectly affect the soil’s microbial properties. In this study different soils irrigated for 0, 1, 8 and 20 years with TWW were sampled and from the east central region of Tunisia. The objective was to investigate its effect on heavy metal accumulation and enzyme activities of β-glucosidase, arylsulfatase, acid phosphatase, alkaline phosphatase, urease, dehydrogenase and fluorescein diacetate (FDA). Moreover, carbon microbial biomass (Cmic) using Substrate induced respiration (SIR) technique and microbial functional diversity using Biolog EcoPlate™ were assessed. Our results had shown a crucial decrease of the enzymatic activities in soils that were newly irrigated with TWW, while a crucial increase was recorded in soils exposed to TWW for 20 years. In addition, chemical analysis revealed an important accumulation of heavy metals such as Cd, Cu, Zn and Ni along with the irrigation period, especially in 20 years-irrigated soils with TWW. The assessment of the bacterial functional diversity showed an important change in Average well color development (AWCD) and in diversity index values. Besides, substrate utilization profile revealed a significant variation along with the irrigation periods. In conclusion, long-term TWW irrigation has increased the metabolic activities of the soil’s microorganisms. Meanwhile, traces elements accumulation could pose a serious threat for biological processes in soils and a limiting factor for the reuse of TWW in agriculture.

Public acceptability of treated wastewater reuse in Saudi Arabia: Implications for water management policy

Treated wastewater reuse is increasingly important for sustainable water resource management, especially in water-stressed countries located in the world's arid regions that rely on groundwater and desalination process for meeting their water demands. This study investigates the socio-demographic variables influencing public perceptions of reusing grey and mixed wastewater for non-domestic uses: firefighting, swimming pools, and car washing. Data were collected from 624 households in the Dammam Metropolitan Area, Saudi Arabia using a structured questionnaire and analyzed using descriptive and inferential statistics. The results from logistic regression indicates that the likelihood of a household to accept reusing treated mixed wastewater is influenced by gender with odds ratio (OR) of 2.71–2.18, residential location (OR = 1.32–1.03), age (OR = 1.22–0.18) and educational level (OR = 1.33–0.98), with a tendency for more acceptance of treated grey wastewater than mixed wastewater. These findings showcase the difficulty that the country could face concerning the public acceptance of treated wastewater for non-domestic uses to augment current freshwater sources even among the educated class. This study is significant because sustainably meeting the country's rising water demands requires the stringent implementation of strategic wastewater reuse policy, including bold steps towards wastewater streams segregation, and intensive public awareness campaigns to change negative perceptions on treated sewage effluent. This study concludes that a substantial reduction in the country's reliance on costly desalinated water and fast depleting non-renewable groundwater requires complete reuse and recycling of treated wastewater for wider non-conventional purposes.

Campylobacter risk for the consumers of wastewater-irrigated vegetables based on field experiments

Water scarcity is emerging as a major problem in water stressed regions such as Middle East countries which highlights the importance of agricultural reuse of wastewater as a valid alternative source. However, consumption of wastewater-irrigated crops has been implicated as a vehicle for transmission of bacterial infections such as campylobacteriosis. Understanding and minimizing public health threats associated with agricultural reuse of treated wastewater (TWW) are crucial elements in sustainable water resource management. To address this need, the present study was carried out to determine Campylobacter risk for the consumers of TWW-irrigated vegetables by field experiments as well as quantitative microbial risk assessment (QMRA) model. Campylobacter was monitored in secondary treated wastewater, TWW-irrigated soil and harvested vegetables by nested real-time PCR assay. Campylobacter was detected in 64% (16/25) of TWW samples, whereas analysis of TWW-irrigated soil and vegetable samples yielded no positive result for Campylobacter. The estimated mean annual Campylobacter disease burden ranged from 2.37 × 10−5 to 6.6 × 10−5 disability-adjusted life years (DALYs) per person per year (pppy) for vegetable consumers which was lower than the less stringent reference level of 10−4 DALYs pppy has been recommended by world health organization (WHO). Our results in regard to the QMRA estimates and field experiments suggest that the reuse of TWW for irrigation of vegetables doesn’t pose a considerable risk to human health from the viewpoint of Campylobacter infections in a semi-arid area.

Hydrological and Environmental Impact of Wastewater Treatment and Reuse on Zarqa River Basin in Jordan

Treated wastewater is an important component of the water resource in Jordan. As Samra wastewater treatment plant—the largest treatment plant in Jordan—discharges ~110 MCM per year of secondary treated municipal wastewater to Zarqa River, and eventually to Jordan Valley. This research aims at assessing the impact of treated wastewater reuse on the hydrology and environment in the most vulnerable areas within Amman-Zarqa Basin, specifically from As Samra treatment plant to Jerash Bridge. Historical data is collected, field survey is performed, and chemical and biological analyses are performed at eleven selected locations along the study area. Afterwards, all collected data is managed using suitable tools to address the impact. The findings of this research demonstrate high improvement in biological and microbial parameters along the flow path, yet the salinity is increased downstream. It is found that this increase is due to brackish water intrusion, apparently from sandstone aquifer. Analysis of BOD and COD carried out as part of this research showed effective system recovery with COD reduction from 130 mg/L at the effluent to less than 50 mg/l in the downstream. Moreover, microbial activities are reduced, mainly due to self-purification in the river.

The agronomic and economic value of treated wastewater reuse for some field crops in desert soil

The agronomic and economic value of treated wastewater reuse for some field crops in desert soil

Wastewater quality index (WWQI) as an assessment tool of treated wastewater quality for agriculture: a case of North Wastewater Treatment Plant effluent of Isfahan.

Treated wastewater reuse is one of the most important ways to confront the water shortage, especially in arid and semiarid regions facing a water crisis such as Iran. This study aims to develop a wastewater quality index (WWQI) to evaluate the effluent quality of the North Wastewater Treatment Plant (WWTP) of Isfahan for agriculture. Three indices, namely overall, acceptability, and health wastewater quality indices (OWWQI, AWWQI, and HWWQI), are developed, using 23 quality parameters of the WWTP effluent. Four different aggregation functions, i.e., weighted arithmetic mean function, weighted geometric function, and two weighted mix functions, are tested. The results revealed that all aggregation functions are free from eclipsing and ambiguity. The weighted arithmetic mean function (WWQI(A)) gave the highest values of OWWQI, AWWQI, and HWWQI, whereas the lowest values were related to the weighted geometric function (WWQI(G)). The sensitivity analysis showed that the OWWQI(G) and OWWQI(Mix1) were more sensitive to the group quality rating values. In all aggregation functions, the OWWQI was more sensitive to groups 5 and 6, while group 1 in the OWWQI showed the least sensitivity. It is concluded that the OWWQI(G) and OWWQI(Mix1) were the most representative aggregation functions for the estimation of the OWWQI.

Public attitude toward expanding the reuse of treated wastewater in the United Arab Emirates

In 2015, the treated wastewater production was 711 million cubic meters (mm3) per year, in which 511 mm3 was used, while the remaining 200 mm3 was disposed in the sea or wasted in desert areas. By 2030, the projected volume of produced wastewater is about 1400 mm3, each drop of which has to be utilized. This study examined the public attitude toward expansion of treated wastewater reuse in the United Arab Emirates (UAE). A multiple-choice questionnaire which covered demographic information, knowledge related to water resources and attitude was prepared and posted online. The answers of 1304 UAE residents (male = 444 and female = 860) were collected, presented and analyzed with the use of T test, one-way ANOVA and Chi-square. Results show that 30% of respondents are aware of the water shortage problem, while the remaining 70% are unaware (30%) or do not know (40%). However, the majority (80%) are taking measures to conserve water and are willing to pay extra fees for having centralized wastewater treatment systems installed where they live. There is a positive attitude toward the use of treated wastewater for some agricultural and industrial purposes. The respondents support the use of treated wastewater for preserving the environment and easing pressure on expensive desalinated water and depleting groundwater. Results also revealed statistical significance toward wastewater reuse based on gender, age, level of education and income. Respondents ranked incentives for reuse of treated wastewater and critics against reuse.

Review on biological wastewater treatment and resources recovery: attached and suspended growth systems.

The treatment of wastewater for reuse is a potential solution to meet ever increasing urban, industrial, agricultural, and environmental demands across the world, where clean water availability is scarce. There are several traditional wastewater treatment processes that offer varying degrees of effectiveness in addition to presenting environmental, economic, and social disadvantages. Development of promising and inexpensive technologies to provide the reusable water in needful amounts using wastewaters as a cheap source of key nutrients and organic matter is required. Wastewater treatment by biological methods is becoming more important in the light of recovering value-added plant nutrients, heavy metals, biosolids, and bioenergy resources. Different types of solid contaminants in effluents can be removed simultaneously by pure cultures or mixed microbial consortia. Based on the structural organization of microbial biomass, biological treatment systems are classified into two types: dispersed growth system and attached growth system. Biological treatment methods associated with fixed-film growth have been recognized as highly effective and more energy efficient than suspended growth systems. This review discusses the recent breakthroughs in advanced biological wastewater treatment using both the systems, and also focuses on key energetic resources recovery driven by biological technologies.

Treated Wastewater Reuse: An Efficient and Sustainable Solution for Water Resource Scarcity

Wastewater has become a valuable resource in many regions of the world that face increased level of freshwater scarcity. Reuse of treated wastewater has high economic benefit, but it can also lead to environmental pollution. As such, explicit conditions must be defined to determine the optimality of wastewater reuse for society. In this paper, we develop a regional multi-sectoral model of water quantity–quality interaction among the urban, agricultural, and environmental sectors. Our interest lies in the feasibility of reuse, rather than the stability of the regional arrangements, therefore we apply a social planner’s approach to this regional problem. We formally construct sufficient conditions that support the superiority of infrastructure development and conveyance of treated wastewater for irrigation, when measured against other common disposal alternatives. Using a numerical illustrative example, which relies on data and results from existing literature, we were able to replicate our theoretical findings, as well as to examine their robustness, when supporting assumptions are relaxed.

Industrial Waste water Treatment and Reuses for Agricultural Purpose

In the present study, the treatment of industrial wastewater and reuses for agriculture purpose. The photocatalytic degradation of dyes like bismarck brown Y dye has been used as technique for treatment in a batch reactor under solar light in heterogeneous slurry utilizing various concentrations of ZnO as photocatalysts semiconductors. Parameters has been studied (catalyst type, catalyst concentration, pH of dye solution and dye concentration at the beginning). The results show that the best dose of ZnO is 0.80 g/l, and the optimum pH is 10. The percentage removal of chemical oxygen demand (COD) of the dye solutions was higher than that of the degradation of dye for the same conditions of catalyst. Treated wastewater reuse in agriculture is a common practice in the Mediterranean countries and there is a considerable interest in the long-term effects of treated wastewater on crops intended for human consumption. This paper studies the fundamentals of agricultural irrigation using treated wastewater and the status of industrial wastewater reuse in Iraq with studies related to the effects on soils and plants.

Treated wastewater reuse in micro-irrigation: effect of shear stress on biofilm development kinetics and chemical precipitation

ABSTRACT Treated wastewater in micro-irrigation is a promising approach that could be used to decrease the pressure on good quality water resources. However, the clogging of such systems due to biofilm development and chemical precipitation constitute a constraint with the use of treated wastewater (TWW) and lead to lower irrigation system performance. The objective of this work is to study the development of biofilm and composition of fouling due to TWW under shear stresses of 0.7, 2.2 and 4.4 Pa detected along micro-irrigation systems. For this purpose, a Taylor-Couette reactor (TCR) was specifically calibrated for the cultivation of biofilm. The analysis of fouling composition samples (organic and inorganic) shows that biofilm tends to develop under the highest shear stress value (4.4 Pa). Precipitation of calcium carbonate in the form of calcite was observed in conjunction with biofilm growth using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). These results can be used to ascertain the origins of chemical and biological clogging of drippers and fouling of pipes related to reclaimed water- irrigation.

Evaluation of phytotoxicity of effluents from activated sludge and constructed wetland system for wastewater reuse.

The aim of this study was to evaluate the phytotoxicity of wastewater treated with horizontal subsurface flow (HSSF) constructed wetlands (CWs) and activated sludge (AS) system using disinfection treatment such chlorination and ultraviolet (UV) system. To assess the impact of the reuse of different effluents (HSSF-Cl, HSSF-UV, AS-Cl and AS-UV), bioassays using seeds of Raphanus sativus (R. sativus) and Triticum aestivum (T. aestivum), were performed on both Petri dishes and soil. Different treated wastewater concentrations were varied (6.25%, 12.5%, 25%, 50% and 100%) and the percentage of germination inhibition (PGI), percentage of epicotyl elongation (PEE) and germination index (GI) were determined. Positive effects (PGI and PEE <0% and GI >80%) of HSSF-Cl, HSSF-UV, AS-Cl and AS-UV effluents on germination and epicotyl elongation of R. sativus and T. aestivum were observed in Petri dishes bioassays. However, toxic effects of HSSF-Cl, HSSF-UV and AS-Cl on seeds germination and epicotyl elongation of both plant species were detected in soil samples (PGI and PEE >0% and GI <80%). Only R. sativus seeds to be irrigated with AS-UV achieved GI values above 86% for all concentrations evaluated. These results indicated that AS-UV effluent had a positive effect on seeds germination and can be recommended for treated wastewater reuse in agricultural irrigation.

The impact of irrigation water management techniques on the performance of rice using treated wastewater reuse in Durban, South Africa

Abstract The need to cultivate effluent-irrigated rice is paramount and synonymous with treated wastewater reuse, recycling and water resources management. A trial in a peri-urban set-up with a low-cost decentralized wastewater treatment system (DEWATS) was carried out in the 2017 and 2018 cropping seasons to assess the effect of irrigation water reuse management techniques on the yield and water productivity of rice. It was hypothesized that anaerobic baffled reactor (ABR) irrigation water management does not have an effect on the yield of peri-urban grown rice. The impacts of irrigation water management techniques were very significant (P &amp;lt; 0.001) on the number of irrigation events, amount of irrigation and daily water balance. The impact was not significant (P &amp;gt; 0.05) on the tiller numbers per plant; it was however significant (P &amp;lt; 0.05) on the panicle numbers per plant. The effects were not significant (P &amp;gt; 0.05) on the plant height but significant (P &amp;lt; 0.05) on the yield rice for both trials. The effect was also significant (P &amp;lt; 0.05) on water productivity. The result proved that the hypothesis be rejected. It could be concluded that significant potential exists for applying wastewater reuse for non-drinking applications such as irrigation.

Accumulation of trace elements by corn (Zea mays) under irrigation with treated wastewater using different irrigation methods

Treated wastewater reuse for irrigation has gained a greater significance as an alternative resource to meet the growing water demands for agriculture and reduce the pressure on limited existing fresh water. However, this reuse needs adapted management in order to avoid environmental and health risks. An experiment was conducted in a greenhouse to evaluate the effect of different irrigation methods on the Metallic Trace elements and metals concentrations of a Tunisian soil (pH = 8.6) and corn when using treated wastewater. Four irrigation methods: surface irrigation, sprinkler irrigation, drip irrigation and subsurface drip irrigation, and two water qualities were used: treated wastewater and fresh water. Samples of soil and corn were analyzed for several Metallic Trace elements. Results for soil showed that treated wastewater increased electrical conductivity, nutrients and metallic trace elements. The highest levels of salinity and Metallic Trace elements were recorded with using surface irrigation and the lowest were noticed by using subsurface drip irrigation. Whereas the highest levels of nutrients elements were recorded by using subsurface drip irrigation. Results for corn showed that irrigation with treated wastewater improved corn biomass, increased nutrient elements, nitrate reductase activity and chlorophyll content. The concentrations of Metallic Trace elements in different parts of corn were significantly higher under treated wastewater irrigation than fresh water irrigation and were reduced in case of subsurface drip irrigation. Among studied metals, Nickel concentration exceeded the permissible limits of 10 mg kg−1. Bio-concentration factor values were, in order, Iron > Zinc > Nickel > Copper > lead > Cadmium, whereas, translocation factor values were, in order, Copper > Zinc > Cadmium > iron > lead > Nickel. Because of translocation factor < 1 and bio-concentration factor ≥ 0.2, maize could be considered as both an excluder and an accumulator plant. Results of this study indicate that the use of subsurface drip irrigation decreased the amount of soil and corn contamination by Metallic Trace elements.

Expounding the role of interference on the recovery of nutrient fractions from aqua matrix using calcined gastropod shell

The need to elucidate the influence of the presence of the major components (i.e. organic matter phosphate and nitrate) of nutrient-rich wastewater on the process of nutrient recovery, using calcined gastropod shell (CGS), necessitated this study. The time–concentration profiles of the recovery of organic matter, phosphate and nitrate were studied in synthetic feed water that contained single adsorbate of interest. Both the single and binary component equilibrium isotherm parameters were derived to explicate and quantify the impact of the presence of each constituent of the nutrient rich wastewater on the process of resource recovery. The time-concentration profiles of all the recovery processes showed that the process of nitrate recovery is the rate limiting step in the use of CGS as the reactive material. The pseudo second order kinetic equation gave the best description of both the nutrient and organic matter recovery but the processes were described by different equilibrium isotherm equations. The determination of the efficiency of interference on nutrient recovery showed that nitrate and organic matter exhibited minimal influence on phosphate recovery but the presence of phosphate and organic matter significantly impacted nitrate recovery. The recovery of organic matter was not vitiated by the presence of either phosphate or nitrate. The real life implications of the findings from this study showed that the use of CGS as a reactive material in resource recovery from a nutrient-rich wastewater would provide a double-pronged approach for resource recovery and appreciable treatment of wastewater for reuse.

Biochemical and transcriptomic response of earthworms Eisenia andrei exposed to soils irrigated with treated wastewater.

In order to ensure better use of treated wastewater (TWW), we investigated the effect of three increasing doses of TWW, 10%, 50%, and 100%, on biochemical and transcriptomic statuses of earthworms Eisenia andrei exposed during 7 and 14 days. The effect of TWW on the oxidative status of E. andrei was observed, but this effect was widely dependent on the dilution degree of TWW. Results showed a significant decrease in the catalase (CAT) activity and an increase in the glutathione-S-transferase (GST) activity, and considerable acetylcholinesterase (AChE) inhibition was recorded after 14 days of exposure. Moreover, malondialdehyde (MDA) accumulation was found to be higher in exposed animals compared to control worms. The gene expression level revealed a significant upregulation of target genes (CAT and GST) during experimentation. These data provided new information about the reuse of TWW and its potential toxicity on soil organisms.

Public perceptions of reusing treated wastewater for urban and industrial applications: challenges and opportunities

The growing water scarcity and quality deterioration promote the development of new water resources. Development of water treatment technologies has made water recycling and wastewater reuse a feasible solution to current limitations. However, water recycling plan and reuse has been halted repeatedly by the lack of public acceptance. This study focused on understanding public concerns and perceptions regarding treated wastewater reuse. The study also investigated how public perceptions might affect the current and future utilization of the resources in Muscat, Sultanate of Oman. The public’s perceptions and opinions were achieved by conducting a questionnaire survey from 115 randomly selected residents with different backgrounds. The results indicated that the residents were positive to support any possible option that supported human health and the environment. The majority of the statistical society was optimistic about the reuse of the treated wastewater for irrigation purposes (except for non-edible crops), urban practices, recharge of groundwater, and industrial activities. Using as drinking water was the least preferred option according to the survey. The outcome of this survey study can be used to address the public concerns regarding wastewater-reuse practices. Additionally, this study hopes to support the effective management plans in the future.

A technical-economical approach to promote the water treatment & reuse processes

Despite the emergency of water scarcity, the man's choices have always been directed towards the mismanagement of this vital resource; drinking water is far from being a right for everyone and is rather scarce and poorly distributed in many areas of the world. The aim of this work is to set up a water cost evaluation methodology based on the energetic equivalence among all the possible treatment strategies, water sources and water end-uses. An economic incentive is proposed on the basis of the thermodynamic and process analysis of a Wastewater Treatment & Reuse (WWTR) Plant. The analysis extends our previous approach to the whole panorama of the water-cycle related technologies. The energy use intensity of different (in-series) process of a water reuse project has been addressed: from the COD and nutrient removal, to the energy harvesting and to the separation of dissolved ions. The incentive is able to reward the processes having the goal of low energy consumption and low carbon emissions. The methodology has been applied to WWTR projects at different scales. The results showed that it is possible to obtain an acceptable Return of Investment (ROI), even for a low plant productivity (around 200 m3/day). Moreover, based on the profitability of the WWTR Project, the calculation of the “true value” of the “water source” has been presented. An acceptable price of waster (as a commodity) is evaluated for both wastewater and seawater by varying the potentiality of the water reclamation plant. This calculation could be implemented to evaluate the economic benefit of public investment as well as to reduce the use of water from non-renewable sources.

Factors influencing the reuse of reclaimed water as a management option to augment water supplies.

The reuse of treated wastewater, whether direct or indirect, can raise public concerns as a result of the overall risk perception. As such, community acceptance plays a significant role in the implementation of alternative water systems. Public attitudes towards water reuse are highly influenced by perceived health risk, religious prohibition, political issues, and the degree of human contact with recycled water. In most of the Mediterranean countries, wastewater is reused to different extents either within planned or unplanned schemes. Unfortunately, there are few in-depth studies of the socio-cultural aspects of reuse projects in developing countries, and Lebanon is no exception. Accordingly, this research will comprehensively tackle the issue of public knowledge, perceptions, and acceptance from different perspectives in an effort to provide national baseline information on wastewater reuse that is needed for future regulatory and developmental projects. As such, a survey was developed, tested, and administered. Results showed an inverse relation between the degree of human contact with the treated wastewater and public acceptance. People were found to be more inclined towards reuse for purposes with minimal human contact such as landscaping and agriculture with opposition when it came to use for personal use. Moreover, the results showed a general lack of trust in governing institutions and authorities, which could explain perceived health risks and perceptions of risk resulting from system failure. Overall, the willingness to use treated wastewater was found to vary as a function of the "disgust factor," religious beliefs, and perceptions of a high risk towards contracting waterborne diseases. The disgust towards reuse of treated wastewater was found to be a strong predictor affecting willingness to reuse whereby those who believed it is disgusting to reuse treated wastewater were found to be on average, three times less likely to reuse treated wastewater as compared to those who did not declare disgust. Similarly, a significant association was found between religious beliefs and respondents' willingness to use treated wastewater. Interviewees who thought treated wastewater reuse is not religiously accepted were, on average, twice less likely to use treated wastewater as compared to those who did not believe that reuse contradicts with their religious beliefs. Additionally, people's perceptions on associating the spread of water-borne diseases with reuse were found to be significant. Those who perceived that reusing treated wastewater would lead to diseases and affect the human health, were on average, twice less likely to accept reuse. Developing a comprehensive strategy that integrates increasing awareness and knowledge, setting policies related to water reuse, building public trust and communication channels, increasing public participation/engagement in decision making, and developing a sustainable management framework is thus crucial before any investments are made in reclaimed water-reuse projects.