Safe Wastewater Reuse Research Articles

Simultaneous nitrogen removal and toxicity reduction of synthetic municipal wastewater by micro-electrolysis and sulfur-based denitrification biofilter

Simultaneous nitrogen removal and toxicity reduction are critical for safe reuse of wastewater, but research in this area is limited. In this study, micro-electrolysis and sulfur-based denitrification biofilters (DNBFs) were applied for simultaneous nitrogen removal and toxicity reduction for municipal wastewater. When COD was 250 ± 1 mg/L, NO3–-N was 50 ± 1 mg/L, total nitrogen (TN) of effluent was below 5 mg/L with the nitrogen load of 0.149 kg N/(m3·d) in all the reactors, while the effect of electrolysis on TN removal was not obvious. Micro-electrolysis promoted toxicity reduction by 8.7–17.4% only in sulfur-based DNBFs, and it also increased biofilm PN/PS by 7.56–43.46% and enhanced Cloacibacterium’s abundance responsible for toxicity reduction (p < 0.05). Introduction of sulfur resulted in the contribution of sulfur-based autotrophic denitrification up to 21.48% and Sulfurimonas mainly contributed to toxicity reduction (p < 0.05).

UV-LED for Safe Effluent Reuse in Agriculture

In the face of the water scarcity problem, the use of treated wastewater emerges as a viable alternative to meet the demand of the agricultural sector, the main consumer of available water in the world. Thus, the development of technologies to provide safe wastewater reuse is a priority. We evaluated the reduction rate of the fecal indicator Escherichia coli naturally present in effluent from an urban wastewater treatment plant (WWTP) submitted to UV-LED (Ultraviolet-Light-Emitting Diodes) radiation, emitting UVA (365 and 405 nm) or UVC (255 and 280 nm), used alone or coupled. The 280-nm wavelength seems to be crucial to the success of the disinfection systems, as all the programs that used this wavelength reached a 4-log reduction of E. coli.

A spatial decision support system for optimally locating treatment plants for safe wastewater reuse: an application to Saudi Arabia

A spatial decision support system for optimally locating treatment plants for safe wastewater reuse: an application to Saudi Arabia

Investigation of chlorine tolerance profile of dominant gram negative bacteria recovered from secondary treated wastewater in Jaipur, India

Management of bacterial survival post chlorine disinfection is vital for safe wastewater reuse for irrigation, as the presence of microorganisms in large numbers may lead to subsequent contamination of the surface and ground water reservoirs. Even after satisfying the current norms of coliform counts after disinfection (less than 1000 MPN per 100 mL), chlorine tolerant bacteria surviving in inadequately treated wastewater may pose a public health threat as many of these bacteria are able to re-grow upon storage. The current study is aimed to assess the magnitude of the problem posed by chlorine tolerant bacteria during chlorine disinfection and attempts to derive a strategy for safe disinfection. The chlorine tolerance was examined in the dominant gram negative bacteria (GNB) recovered from secondary treated sewage from a treatment plant located at Jaipur, India. Bacterial survival and re-growth (after 24 h) studies on test species (n = 11) with reference to E.coli ATCC 25922 reveal that, while the lethal doses of isolates ranged from 0.5 to 1.25 mgL−1,the chlorine doses for complete inhibition of re-growth were much higher (0.75–1.75 mgL−1).The isolates showing highest lethal dose and re-growth inhibition dose, identified as Citrobacter freundii, Klebsiella sp. and Stenotrophomonas maltophilia also exhibited very low log effective reduction (0.72–1.90) values and were selected as chlorine tolerant bacteria. Results of inactivation kinetics experiments on chlorine tolerant bacteria reveal a strong correlation (R2 > 0.89–0.99) between log reduction values and contact time. In re-growth kinetics experiments, maximum re-growth was observed after 6 h exposure following which, only marginal increase was registered up to 24 h. The study indicates that the existing approach of bacterial elimination post chlorine treatment may be grossly inadequate to assess the performance of the disinfection process adopted for drinking water treatment. It further brings out a novel approach to arrive at meaningful chlorine doses that take bacterial re-growth into account for achieving safe disinfection.

A Review on the Current Knowledge and Prospects for the Development of Improved Detection Methods for Soil-Transmitted Helminth Ova for the Safe Reuse of Wastewater and Mitigation of Public Health Risks

Climate change, increase in population and scarcity of freshwater have led to a global demand for wastewater reuse in irrigation. However, wastewater has to be treated in order to minimize the presence of pathogens, in particular, the ova of soil-transmitted helminthes (STHs). Limiting the transmission via removal of STH ova, accurate assessment of risks and minimizing the exposure to the public have been recommended by health regulators. The World Health Organization (WHO) guideline specifies a limit of ≤1 ova/L for safe wastewater reuse. Additionally, the Australian Guidelines for Water recycling (AGWR) recommend a hydraulic retention time of over 25 days in a lagoon or stabilization pond to ensure a 4 log reduction value of helminth ova and to mitigate soil-transmitted helminths associated risks to humans. However, the lack of fast and sensitive methods for assessing the concentration of STH ova in wastewater poses a considerable challenge for an accurate risk assessment. Consequently, it has been difficult to control soil-transmitted helminthiasis despite effective mass drug administration. This limitation can be overcome with the advent of novel techniques for the detection of helminth ova. Therefore, this review presents an assessment of the current methods to detect the viable ova of soil-transmitted helminths in wastewater. Furthermore, the review focuses on the perspectives for the emerging state-of-the-art research and developments that have the potential to replace currently available conventional and polymerase chain reaction based methods and achieve the guidelines of the WHO in order to allow the safe reuse of wastewater for non-potable applications, thereby minimizing public health risks.

Water Reclamation and Reuse.

Literature published in 2017 related to water reclamation and reuse is reviewed in four categories: sustainable reuse, treatment technology, implementation, and assessment and management. The development and improvement of conventional treatments and new methods that afford safe wastewater reuse are examined.

Solar Wastewater Treatment (SOWAT) and Reuse for Agricultural Irrigation

AbstractSolar wastewater treatment (SOWAT) was the subject of experiment between April and September using low cost and mastery equipment: ‘hot‐box’ stills. Using a separate still, treated wastewater (i.e. distillate) production was recorded between 2.4 and 6 l m−2 day−1. Treatment efficiency was comparable to the activated sludge treatment process. Biological oxygen demand (BOD) recorded between 86 and 90% of abatement. Raw wastewater turbidity was reduced by 99%, from 181 nephelometric turbidity units (NTU) to 1.6 NTU. The treatment also allowed wastewater disinfection. The inactivation of total coliforms, faecal coliforms and faecal streptococci was estimated at about 99%.SOWAT offers the advantage of grouping, in a separate piece of equipment, three steps of conventional wastewater treatment: (i) the pre‐treatment, (ii) the biological and (iii) disinfection treatments. Also, this sustainable treatment does not consume electricity and consequently does not emit greenhouse gases (GHGs).Used on a medium and large scale, SOWAT would be promising for safe wastewater reuse in agriculture. This could secure food production of poor and low‐income countries, especially those that are very sunny. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Waste water management and water quality of river Yamuna in the megacity of Delhi

The present study aims at assessing water quality of river Yamuna in one of the world's most polluted and populated megacities, Delhi. Conductivity, salinity and sodium content were within the permissible categories. Chloride concentration exceeded acceptable levels of drinking water guidelines. Water quality was poor at all locations with respect to heavy metal contamination, especially along the lower section of the Delhi stretch. Heavy metal concentrations were manifold higher than the acceptable limits of drinking water according to the BIS guidelines and reached similar to 29, 4.9, 10, 31, 27, 83, 7.3 and 27 times higher, respectively, for metals aluminum, copper, chromium, cadmium, iron, lead, manganese and nickel. The Najafgarh and the Shahdara drains are major point sources. Low oxidation-reduction potential reflected high organic loads and traces of eutrophication together with significant levels of nitrate and total phosphate. Discharges from agriculture, sewage and power plants could be important sources of high metal concentration. This calls for urgent measures to be taken for prevention of metal contamination in the river, through both, technology as well as implementation of regulations in order to sustain huge populations in megacities like Delhi. Waste water treatment from point sources needs tremendous improvement on the city. Treatment of the entire waste generated up to the tertiary level is required for minimizing dissolved solids, especially toxic metals, and rendering reuse in agriculture suitable. Treatment plants need proper operation, maintenance, uninterrupted power supply and regular monitoring. Various measure and programmes need to be undertaken to ensure safe reuse of wastewater.

The safe re-use of wastewater for agriculture is a desired goal in many arid zone countries. The potential of greywater as alternative irrigation source for vegetable crops was investigated. To-mato, pea and cantaloupe plants were drip irri-gated with both fresh Nile water and greywater to access the impact on yield production and asso-ciated environmental and health risks. The biolog-ical properties

The safe re-use of wastewater for agriculture is a desired goal in many arid zone countries. The potential of greywater as alternative irrigation source for vegetable crops was investigated. To-mato, pea and cantaloupe plants were drip irri-gated with both fresh Nile water and greywater to access the impact on yield production and asso-ciated environmental and health risks. The biolog-ical properties

Establishing Surrogate–Virus Relationships for Ozone Disinfection of Wastewater

Abstract Safe reuse of wastewater requires high levels of pathogen inactivation. Ozone is a very effective disinfectant for viruses and has distinct benefits over other forms of disinfectants, in that it increases the clarity of water and can oxidize some chemical contaminants in water. However, because of the combination of high ozone demand of most wastewaters and rapid reaction with viruses, determination of ozone dose in wastewater and recycled water treatment is not well defined. While various surrogates are used as indicator organisms for human pathogenic viruses in water reuse practice, much less is known about the relationship between surrogates and human pathogenic viruses for ozone disinfection in wastewater. In this study, the ozone inactivation dose response of several surrogates (Escherichia coli, coliphage T1, T4, PRD-1, ΦX174, and MS2) and human pathogenic viruses (poliovirus 1, echovirus 11, coxsackievirus B5, and adenovirus 2) were compared for the first time in secondary effluent wastewa...

Tertiary treatment for wastewater reuse based on the Daphnia magna filtration - comparison with conventional tertiary treatments.

Tertiary treatments are required to permit safe reuse of wastewater. The performance of a new biological tertiary treatment based on the filtration by a population of Daphnia magna was studied and compared with the performance of other conventional tertiary treatments such as coagulation-flocculation, settling tank, disc filtration, sand filtering and ultraviolet (UV) light. The analysis was based on the efficiency in the particle removal and Escherichia coli inactivation. The Daphnia magna treatment reduced the concentration of particles with diameters below 30 μm by 35%, depending on abiotic parameters such as water temperature and the hydraulic retention time (HRT). The Daphnia magna filtration increased with water temperature for water temperatures >20 °C, while it remained constant for water temperatures <20 °C. Lower HRTs induced the growth of the Daphnia magna population, maintaining the same water quality. Furthermore, the Daphnia magna treatment inactivated E. coli in 1.2 log units. This inactivation was six times larger than that obtained by the conventional macrofiltration systems analyzed, although lower than the inactivation attained by UV light, which ranged between 1.5 and 4 log units.

Nanotechnology-based water treatment strategies.

The most important component for living beings on the earth is access to clean and safe drinking water. Globally, water scarcity is pervasive even in water-rich areas as immense pressure has been created by the burgeoning human population, industrialization, civilization, environmental changes and agricultural activities. The problem of access to safe water is inevitable and requires tremendous research to devise new, cheaper technologies for purification of water, while taking into account energy requirements and environmental impact. This review highlights nanotechnology-based water treatment technologies being developed and used to improve desalination of sea and brackish water, safe reuse of wastewater, disinfection and decontamination of water, i.e., biosorption and nanoadsorption for contaminant removal, nanophotocatalysis for chemical degradation of contaminants, nanosensors for contaminant detection, different membrane technologies including reverse osmosis, nanofiltration, ultrafiltration, electro-dialysis etc. This review also deals with the fate and transport of engineered nanomaterials in water and wastewater treatment systems along with the risks associated with nanomaterials.

Effect of wastewater chlorination on endocrine disruptor removal

Endocrine disrupting chemicals (EDCs) are compounds of mainly anthropogenic origin that interfere with the endocrine system of animals and humans thus causing a series of disorders. Wastewater treatment plants are one of the major routes for transporting such chemicals to the water courses. In the context of this study, several chlorination batch tests were performed in order to assess the effectiveness of chlorination to remove bisphenol A (BPA), triclosan (TCS), nonylphenol (NP) and its ethoxylates (NP1EO and NP2EO) from secondary effluent. According to the results, an appreciable removal of NP, BPA and TCS to the order of 60-84% was observed as an effect of moderate chlorination doses. This was not the case for NP1EO and NP2EO as even at high chlorine doses, removal efficiencies were lower (37% for NP1EO and 52% for NP2EO). Removal efficiencies of NP, BPA and TCS are practically independent of contact time, although this was not the case for NP1EO and NP2EO. Based on toxicity experiments, it is anticipated that following chlorination of the target chemicals, production of more toxic metabolites is taking place. Therefore the effectiveness of chlorination to remove EDCs is questionable and more research is needed to guarantee safe wastewater reuse.

Evaluation of the WHO helminth eggs criteria using a QMRA approach for the safe reuse of wastewater and sludge in developing countries

An analysis of the actual WHO recommendations to develop standards for the safe reuse of wastewater, excreta or sludge in agriculture using a quantitative microbial risk assessment (QMRA) is presented. The proposed values are defined using a risk-based model for Ascaris lumbricoides infection to assess the human risks associated with exposure to this pathogen from crops irrigated with polluted water, or from crops grown in biosolid-enriched soil. From the results it becomes evident that, with regard to helminth eggs, the WHO guidelines for wastewater reuse in agriculture seem more stringent than are needed in developing countries, while for the reuse of sludge they appear to be the opposite. Although more information is needed to confirm this conclusion, which was derived from a single piece of research, at the very least a more cautious approach is recommended when evaluating excreta or sludge for agricultural purposes in developing countries. Additionally, this work shows that the application of some barriers, other than wastewater and sludge treatment as suggested by WHO, can play an important role in controlling risks.

Science and technology for water purification in the coming decades

One of the most pervasive problems afflicting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water-rich. Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy, while at the same time minimizing the use of chemicals and impact on the environment. Here we highlight some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re-use of wastewater and efficient desalination of sea and brackish water.

Confronting the realities of wastewater aquaculture in peri-urban Kolkata with bioeconomic modelling

Wastewater reuse for aquaculture is a reality in several Asian countries, however, traditional practices face constraints including inadequate or contaminated wastewater inputs and growing concern over health risks. Based on Kolkata and a wastewater flow of 550,000 m 3 d −1, rational and conventional designs for lagoon-based wastewater treatment and reuse through aquaculture were compared using bioeconomic modelling. Outcomes showed the rational design required a larger area than the conventional or traditional systems, but that financial returns, nutrient retention and fish production were higher; gross fish production employing rational and conventional designs was 45,500 and 11,560 t, respectively. However, limited land availability and constraints to reconfiguring the existing system make implementation of the rational design unlikely. Findings suggest traditional practices could be enhanced by adopting wastewater treatment prior to reuse, modifying fish production strategies, and monitoring to safeguard health. Bioeconomic modelling constitutes a useful tool in comparing treatment and reuse options, permitting the sensitivity of financial returns to changing costs and recent revisions to WHO guidelines for safe wastewater reuse to be assessed, however, social and environmental consequences demand consideration.

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

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

International Perspective on Water Resources Management and Wastewater Reuse – Appropriate Technologies

The unabated urbanization and industrialization process in many arid and semi-arid countries leads to increasing demand for municipal and industrial water supply, often in direct competition with irrigation demand. In such cases wastewater reclamation and reuse should be an integral component of water resources management strategies. National reuse policies should be developed and implemented taking into account local conditions and based on affordable approaches that ensure safe reuse practice. This paper describes research and development carried out in several developing countries on appropriate technologies for implementing reuse, as well as coordinated international efforts to provide recommended guidelines and policies for safe wastewater reuse in agriculture and aquaculture.