Wastewater Utilities Research Articles

Heavy metal contents, soil-to-plant transfer factors, and associated health risks in vegetables grown in western Iran

Due to the utilization of municipal and industrial wastewater, as well as the uncontrolled use of chemical and livestock fertilizers leafy vegetables have a high content of heavy metals (HMs). Soils and eight vegetable samples extensively used in Iran were collected from numerous vegetable farms to investigate the risk of HMs pollution and human health risk in Hamadan province, western Iran. Based on the results, it was found that the tested species differed in the content of HMs. Most of the HMs studied were found to be inside the maximum permissible limits (MPL) except for Cd (1.46–2.40 mg kg−1 DW, for Coriandrum sativum L. (coriander) and Ocimum basilicum L. (basil), respectively and Pb (13.5–21.8 mg kg−1 DW, for Petroselinum crispum (Miller) (parsley) and basil, respectively) which were higher than the MPL. The transfer factor (TF) of HMs in eight vegetables was estimated, and HMs varied greatly between vegetables. The TF values of the studied HMs were ordered based on the mean values of TF in all vegetables: Cd (1.48) > Zn (0.60) > Pb (0.39) > Cu (0.32) > Mn (0.14) > Ni (0.12) > Fe (0.03). The health risk index (HRI) values for the studied HMs for adults were less than 1 except for Cd and Pb. Basil, Mentha piperita L. (peppermint), and Anethum graveolens L. (dill) were chosen as high accumulators of Cd and Pb based on TF and HRI. The health risks connected with the Cd and Pb content of vegetables cultivated in western Iran are highlighted in this study, which implies that required steps should be done to reduce Cd and Pb accumulation in western Iran's vegetables.

Occurrence and risk assessment of trace organic contaminants and metals in anaerobically co-digested sludge

Anaerobic co-digestion of sludge increases biogas production and maintains anaerobic digestion stability. However, it is unclear whether the addition of co-substrates may increase the concentration of trace organic contaminants (TrOCs) and metals, limiting potential resource recovery opportunities when applied to agricultural land. This study explored the occurrence of 20 TrOCs and 18 metals in wastewater sludge anaerobically co-digested with beverage rejects (cola, beer and juice) and food wastes. TrOCs results showed that cola reject caused an accumulation of caffeine in final digestate. Bisphenol A also significantly increased in food waste co-digestion when compared with the mono-digestion (control). No significant difference in TrOCs was observed in the juice reject co-digestion. Analysis of the metal composition revealed a significant increase in Cr and Al in juice reject co-digested sludge. While restaurant food waste increased concentrations of K and Ca, both of which may be beneficial when applied to land. All metals in this study were below the maximum permissible concentrations specified for agricultural land use in Australia. Environmental risk assessment of sludge when used as soil fertiliser, showed that caffeine, diuron, triclocarban, triclosan, Cu and Zn exhibited high risks, with the largest risk quotient (RQ) posed by caffeine. Estrone and naproxen implied medium risks, and ibuprofen implied a high risk except for the co-digestion using cola reject (RQ = 0.9, medium risk). The results emphasise the importance for wastewater utility operators to understand the impact of co-substrate selection on the quality of sludge to minimise environmental risk from the use of biosolids on agricultural land.

Strategies of Utilising Agriculture Wastewater for Microalgae Cultivation and Its Possible Applications: A Review

Microalgae have been found to have high prospects in wastewater treatment, particularly from agriculture. However, the uneconomical algal medium growth has become the major disadvantaged in algal industry. Multiple attempts includes the development of microalgae phycoremediation technology has been integrated into wastewater treatment to reduce the cost of expensive wastewater remediation. Utilising wastewater as a low-cost nutrient medium offers a synergistic effect of wastewater nutrient removal and co-production of valuable biomass simultaneously. This paper is mainly focused on potential, ability, strategy, application (i.e., palm oil wastewater), limitation and challenges of microalgae in agricultural wastewater treatment using phycoremediation. The understanding of cultivating microalgae using agriculture wastewater shall promote the utilisation of wastewater more sustainably in the future. The possible solutions in the application of microalgae for aquaculture and agriculture sector is also discussed in this review. Overall, the utilisation of wastewater in media cultivation for microalgae is restricted due to the expensive treatment and safety concern. However, this pitfall can be reduced in the future together with a further intensive scientific study, advanced technology, better management system and applying better standard protocol.

Comparative study of concrete constructed using wastewater and potable water

80% of the water supplied, normally comes out as wastewater either domestic or industrial. The utilization of wastewater in concrete will reduce potable water usage in the construction industry. Approximately 150 litres of water are required for lm3 of concrete without considering other applications of water in the concrete industry. This research study has investigated the performance of concrete using wastewater. 60 total number of concrete cubes have been designed and constructed using 10%, 20%, 30% and 100% of wastewater. The experimental data indicated that 30% of wastewater content in the concrete mix have increased 18% of the concrete strength compared with the control sample. Meanwhile, the result of the X-Ray Fluorescence Test (XRF) test for the concrete sample recorded that the CA is higher than the 30% concrete sample.

Sustainable Management of Treated Wastewater, the New El-Mahsama Wastewater Treatment Plant in Sinai

As part of the national water resources strategy 2030 of Egypt, safe usage of treated wastewater should be expanded in newly reclaimed lands. In 2020, the first mega-waste water treatment plant (El-Mahsama WWTP) was constructed in the east of the Suez Canal in the Sinai Peninsula to treat 1.0 million m3 per day of El-Mahsama agricultural drain and other small drains, mainly for agricultural purposes in Sinai. However, treated wastewater utilization unwisely may incur several risks to human health, crop yields, livelihood, social and economic conditions, and environmental sustainability. This can be attributed to the possible existence of chemical, biological, or salts in poorly or partially treated wastewater. This research paper aimed at analyzing the best sustainable uses of that treated wastewater of El-Mahsama WWTP in agriculture without causing risks to human and environmental health. Using a qualitative evaluation approach, it was proved that the “favorable sustainable management scenario” includes cropping pattern for the 1st scheme (70,000 feddans) as wheat, barley, beans, and maize, then cropping pattern for the 2nd scheme (about 52,000 feddans) as cotton, flax, kenaf, oil crops as jojoba, jatropha, canola, and sunflower. The socio-economic benefits associated with that favorable management scenario is high. The disposal of agricultural drainage water from the agricultural schemes should be diverted to irrigate forest trees “mahogany”. The compost produced should be safely used after appropriate processing and special treatment of the effluent sludge as animals’ fodder. Furthermore, the sludge should be used after anaerobic digestive processes to produce biofuel energy for the nearby communities’ daily life activities. Wastewater treatment could reduce carbon emissions and accordingly mitigate the climate change risks. Expansion in non-conventional water use could give wastewater a second life with the target to reduce water scarcity, reduce environmental deterioration, increase resilience to climate change and improve people’s livelihoods.

Utilizing treated wastewater in tree plantation in Indian desert: part I – species suitability, plant growth and biomass production

Treated wastewater can partly meet the requirements of water for irrigating tree crops in dry areas to better utilize, produce biomass and reduce land degradation. Seedlings of Acacia nilotica, Azadirachta indica, Eucalyptus camaldulensis, Prosopis cineraria, P. juliflora, Tamarix aphylla, Salvadora persica, S. oleoides and Tecomella undulata were planted and irrigated with bore-well (BW) and treated wastewater (WW) at ½ET (Evaporation-transpiration) and ¾ET. Plants irrigated at BW1/2 attained less height and collar diameter, and showed low growth increments and dry biomass. These variables increased by 1.2-2.0-fold at WW3/4 irrigation. Plants produced 1.4-fold higher biomass with WW over BW, whereas it was 1.5-fold higher at ¾ET over ½ET. Responses of species to BW/WW irrigation differed in biomass allocation to roots and other parts as a mechanism to uptake water and nutrients. Conclusively, A. nilotica, A. indica, P. juliflora and T. aphylla had stronger preference to increased irrigation level, whereas E. camaldulensis, S. persica, S. oleoides and T. undulata had preferred nutrients added through treated wastewater. A. nilotica, E. camaldulensis, P. juliflora and A. indica were best species in growth and biomass production and wastewater utilization. These can be replicated in urban afforestation to enhance bio-product and reduce degradation in environmental quality.

Model-Driven Strategies for Sulfide Control in a Regional Wastewater System Receiving Tannery Effluents in Portugal

Ageing infrastructure are a concern for many wastewater utilities. This is accentuated with the presence of hydrogen sulfide within the sewer headspace, known to induce concrete corrosion, toxicity and odours. Some industrial effluents contain significant sulfide concentrations, however most field studies in the literature refer to domestic networks, or lab/pilot scale sulfide abatement strategies for varied effluents. Hence, the objectives of this work are: (1) To obtain data regarding the evolution of sulfides in a full-scale industrial sewer system in Portugal, receiving wastewater from a number of tanneries; (2) model their fate within the system and (3) experimentally evaluate sulfide precipitation with iron salts. Field work evidenced heavily sulfide loaded effluents, exceeding by far literature values for sewer systems. Modelling was carried out based on the AeroSept+ model, specifically calibrated to this type of effluent. Results showed the model was capable of reproducing the overall levels of sulfide in wastewater and H2S in the sewer headspace, while allowing insights into industrial discharges, originating a set of proposed interventions for sulfide abatement. This may be carried out by iron salts addition, in a ratio of 2.75:1, at existing monitoring stations. This approach was fundamental for an affordable performance assessment, under considerable uncertainty.

Hydrothermal liquefaction of Spirulina platensis in post-carbonization wastewater from sewage sludge

Wet solid waste can achieve good dewaterability through hydrothermal carbonization. However, massive wastewater rich in organics is also generated during the process. Previous studies reported the anaerobic digestion potential of organic wastewater, but its inhibitors cause challenges. In our early work, the aqueous by-product from hydrothermal liquefaction of microalgae has been successfully recycled back into the liquefaction process, leading to an enhanced oil yield. Herein, this study addresses the possibility of wastewater from sewage sludge dewatering as a solvent to convert microalgae for biocrude production under temperature of 260-320 ° C . Results show that the wastewater owned a chemical oxygen demand value of 14 g/L and a total organic carbon value of 5.89 g/L with a nitrogen content of 10.34%. The biocrude yield in this wastewater was 31.3–38.7 wt%, higher than liquefaction in pure water (27–33 wt%). Over 10% increment was reached, demonstrating the potential of organic wastewater as a solvent for biocrude production. Following a slight decrease of the nitrogen content, the higher heating value of the biocrude from the wastewater solvent was close to that formed in pure water, suggesting a non-significant influence on fuel quality. Besides, the enhancing mechanism of wastewater stream on liquefaction was discussed based on various analytical approaches. Compound analysis indicates a reduction of nitrogenous chemicals in the wastewater during liquefaction, which are more likely to be transformed to oil phase forming amides. Therefore, this recycling strategy would help develop novel routes for utilization of organic wastewater, significant for sewage sludge treatment.

Liquid wastes as a renewable feedstock for yeast biodiesel production: Opportunities and challenges

Microbial lipids (bacterial, yeast, or algal) production and its utilization as a feedstock for biodiesel production in a sustainable and economical way along with waste degradation is a promising technology. Oleaginous yeasts have demonstrated multiple advantages over algae and bacteria such as high lipid yields, lipid similarity to vegetable oil, and requirement of lesser area for cultivation. Oleaginous yeasts grown on lignocellulosic solid waste as renewable feedstocks have been widely reported and reviewed. Recently, industrial effluents and other liquid wastes have been evaluated as feedstocks for biodiesel production from oleaginous yeasts. The idea of the utilization of wastewater for the growth of oleaginous yeasts for simultaneous wastewater treatment and lipid production is gaining attention among researchers. However, the detailed knowledge on the economic aspects of different process involved during the conversion of oleaginous yeast into lipids hinders its large-scale application. Therefore, this review aims to provide an overview of yeast-derived biodiesel production by utilizing industrial effluents and other liquid wastes as feedstocks. Various technologies for biomass harvesting, lipid extraction and the economic aspects specifically focused on yeast biodiesel production were also analyzed and reported in this review. The utilization of liquid wastes and the incorporation of cost-efficient harvesting and lipid extraction strategy would facilitate large-scale commercialization of biodiesel production from oleaginous yeasts in near future.

EFFECT OF RECYCLING OF ELEMENTAL CHLORINE FREE BLEACHING EFFLUENT TREATED BY ELECTROCOAGULATION ON PAPER PROPERTIES

This study aimed to determine the effect of recycling elemental chlorine free (ECF) bleaching effluent (D0EpD1 and OD0EpD1) after treatment through electrocoagulation under optimum conditions on paper properties. The effect of pH, current density, time and dose of electrolyte on the reduction of chemical oxygen demand (COD) and color was studied. Maximum decrease in COD and color was found under optimum conditions (i.e., pH 7, treatment time of 30 min, current density of 29.16 mA/cm2, and 1 g/L NaCl). Under these optimum conditions, the reduction in COD and color was of 79.9% and 99.10%, respectively. The reduction in the strength properties of paper, caused by recycling, was found to be insignificant, but a decline of 2.11% for D0EpD1 and of 1.43% for OD0EpD1 in brightness was found. Using the electrocoagulation method to treat the bleaching effluent can prove to have valuable potential towards wastewater utilization, pollution control, and sustainable development of the industry.

An insight into the phosphorus distribution in extracellular and intracellular cell of Chlorella vulgaris under mixotrophic cultivation

Phosphorus is non-substitutable and geographically restricted resource in our environment as an essential nutrient for all life. Microalgae have great performance in phosphorus recovery. However, there are few studies on the dynamics of how phosphorus is taken up and distributed in microalgae. The aim of this study was to investigate the effects of different initial ortho-phosphate concentrations (0, 2, 4, 6, 8, 10 mg P/L) on the phosphorus distribution in soluble microbial products, extracellular polymeric substances and intracellular polymeric substances of Chlorella vulgaris under mixotrophic cultivation. The results showed that the initial phosphorus concentration affected the distribution of phosphorus. And the absorption rate of phosphorus would decrease if the phosphorus concentrations were more than 6 mg P/L. Inorganic phosphate is mainly absorbed and stored in extracellular polymeric substances. Excessive phosphorus promoted the transformation of inorganic phosphate in extracellular polymeric substances to organic phosphate in intracellular polymeric substances. Results are beneficial to the treatment of phosphorus-containing wastewater and subsequent utilization of phosphorus-based fertilizer.

Using Wastewater Surveillance Data to Support the COVID-19 Response - United States, 2020-2021.

Wastewater surveillance, the measurement of pathogen levels in wastewater, is used to evaluate community-level infection trends, augment traditional surveillance that leverages clinical tests and services (e.g., case reporting), and monitor public health interventions (1). Approximately 40% of persons infected with SARS-CoV-2, the virus that causes COVID-19, shed virus RNA in their stool (2); therefore, community-level trends in SARS-CoV-2 infections, both symptomatic and asymptomatic (2) can be tracked through wastewater testing (3-6). CDC launched the National Wastewater Surveillance System (NWSS) in September 2020 to coordinate wastewater surveillance programs implemented by state, tribal, local, and territorial health departments to support the COVID-19 pandemic response. In the United States, wastewater surveillance was not previously implemented at the national level. As of August 2021, NWSS includes 37 states, four cities, and two territories. This report summarizes NWSS activities and describes innovative applications of wastewater surveillance data by two states, which have included generating alerts to local jurisdictions, allocating mobile testing resources, evaluating irregularities in traditional surveillance, refining health messaging, and forecasting clinical resource needs. NWSS complements traditional surveillance and enables health departments to intervene earlier with focused support in communities experiencing increasing concentrations of SARS-CoV-2 in wastewater. The ability to conduct wastewater surveillance is not affected by access to health care or the clinical testing capacity in the community. Robust, sustainable implementation of wastewater surveillance requires public health capacity for wastewater testing, analysis, and interpretation. Partnerships between wastewater utilities and public health departments are needed to leverage wastewater surveillance data for the COVID-19 response for rapid assessment of emerging threats and preparedness for future pandemics.

Performance Assessment System to Wastewater Utilities Strategic Planning

Urban water utilities face growing challenges in compliance with increasingly demanding legislation, tightening budgets, ageing personnel, decreasing infrastructure reliability, increasing operational costs, regulatory pressure, and climate change. Within this context, tracking the alignment of the performance with the mission and strategic objectives of the organization, based on reliable and up-to-date data, is of utmost importance to enable effective and continual improvement management. Organizational performance assessment in the water sector has been a topic of growing attention since the 1990s due to the increase in the role of regulators and tighter legislation. Proactive utilities are incorporating sustainability, resource efficiency, resilience, and continual improvement principles in their practices. Strategic planning provides the road map for management and interconnecting the different areas of the organization. An essential component of strategic management planning is the adoption of a tailored performance assessment system (PAS), allowing a better response to these challenges from the water utility management perspective. This paper presents a novel PAS at the strategic level, which was tested and validated with wastewater utilities, in a co-creation process. The proposed PAS fully adopts the objectives recommended in international standards, with a corresponding set of criteria and metrics, and a validated proposal of reference values for the metrics.

Analysis of Wastewater Treatment and Utilization in Mine Engineering

Analysis of Wastewater Treatment and Utilization in Mine Engineering

Operational carbon footprint of the U.S. water and wastewater sector’s energy consumption

Responding to global climate change requires better accounting of greenhouse gas emissions (GHG) to develop targeted strategies for reducing carbon footprints. Energy demand is a major contributor to operational GHG emissions in the water sector. However, the United States struggles to track GHG emissions in this sector largely due to the absence of a centralized and routinely updated water database, which includes operational information. Previous research focused on estimating operational GHG emissions generated from energy used on site and GHG emissions generated from off-site electricity production, but consumed by the facility. Largely these studies have been conducted at single utilities or cities and rarely at a regional or country scale. In this study, we assess the carbon footprints of operational energy use for 76 wastewater utilities and 64 drinking water utilities across the United States. Additionally, we investigate water-related GHG emissions at a sub-annual scale through three case cities to understand how GHG emissions vary at the monthly scale. Per unit of water, indirect energy in the form of grid electricity is found to be the largest contributor of operational GHG emissions. We estimate the total drinking water and wastewater emissions associated with electricity, natural gas, and fuel oil consumption across the United States to be 26.5 × 109 and 16.2 × 109 kg CO2e, respectively. We find the average carbon footprint per volume of drinking water and wastewater emissions to be 0.46 kg CO2e/ m3 and 0.38 kg CO2e/ m3, respectively—equivalent to 2.1% of total emissions from the U.S. electricity sector each year. The research provides insights into operational GHG emissions of the water sector and advances the understanding of temporal variations in the life cycle of energy use. Through the research we suggest the need for further analyses of environmental impacts at the sub-annual scale and support continued accounting of the water sector.

A composite indicator for measuring the environmental performance of water, wastewater, and solid waste utilities

The aim of this paper is to measure and benchmark the environmental performance of Portuguese utilities jointly active in the three sectors of water supply, wastewater collection and solid waste management. To do so, we suggest the use of a traditional (optimistic) directional distance Benefit of the Doubt index. We complement the analysis by considering also the pessimistic version of the proposed BoD and by implementing a robust and conditional approach. The obtained results show that there is space for improvement in the pressure balance of these utilities, especially for small and very large units, mostly operating in urban areas.

Photocatalytic H2 production with simultaneous wastewater purification over flower-like 1T/2H-MoS2-decorated CNT/CNU isotype heterojunction photocatalyst

Exploring low-cost and earth-abundant photocatalysts to efficiently release H2 from wastewater is an appealing solution for global energy and environmental issues. Here, we successfully prepared flower-like 1T/2H-MoS2-decorated g-C3N4 (thiourea)/g-C3N4 (urea) (denoted as CNT/CNU) isotype heterojunction photocatalysts via a facile ultrasonic dispersion method and researched the photocatalytic H2 generation and pollutant degradation performance in oxalic acid (OA) simulated wastewater. The results displayed that 20% 1T/2H-MoS2@CNT/CNU sample exhibited the highest photoreactivity, and the H2 release rate was 1563.32 μmolg-1h−1, which was about 96 times higher than the CNT/CNU. Meanwhile, it also showed the highest total organic carbon (TOC) removal rate of 67.5%. The increased photoreactivity of nanocomposites can be ascribed to the double-interface system to effectually improve the separation of photoinduced charges. Additionally, the experimental results further confirmed that the loading of flower-like 1T/2H-MoS2 could provide abundant active sites as well as expand the visible-light absorption range. Significantly, photoelectrochemistry measurements and density functional theory (DFT) calculations also confirmed that 1T/2H-MoS2 cocatalysts accelerated the charge migration. On this basis, the mechanism of 1T/2H-MoS2@CNT/CNU promoting hydrogen production and synergistic OA degradation was proposed. This research presents a prospective idea for the utilization of waste water and the simultaneous production of clean energy.

Increasing water and wastewater utility participation in demand response programs

The reliance of water utilities on the electric grid, and their ability to buffer its peak demands, are important components of the energy–water nexus. Demand response (DR) among water and wastewater utilities is an underutilized resource for balancing electric loads and is increasingly important as the energy industry transitions to cleaner but intermittent renewables. Challenges to greater participation include water operators’ risk aversion, DR research that misses water sector stakeholders, the hourly and seasonal variability of water demand, the intricacies of power rate schedules, and a lack of convincing data on payback. Actions by particular groups can help overcome these challenges. Power utilities should acknowledge water operators’ risk preferences, work with them to develop site-specific DR practices, and educate them on rate schedules and DR necessity. Water utilities should learn about their power bills and share information about their water operations that will help power companies assess DR potential. DR researchers should consider water operators’ risk perceptions, explore ways to work around hourly flow variations, involve water sector co-authors in their work, develop DR case studies with cost-benefit analyses, and share their research with water sector audiences. These actions will help increase DR penetration in the water sector.

Stainless Steel Cyclic Voltammograms in Dioscorea Opposita Flour Media

Improving the efficiency of hydrogen gas production in the water electrolysis process draws great attention from many scholars. To improve the efficiency of the process and reduction in the cost, stainless steel has been widely implemented in the industrial water electrolysis process. Electrolyte modification is also one of the methods to improve the water electrolysis process. The study used Dioscorea opposita tuber flour as a media addition in an alkaline solution. The efficiency of water electrolysis was evaluated by cyclic voltammetry. The result showed that the activity of the electrode and energy consumption were increased with values of 29 and 23%, respectively, by adding 3 g of the media. However, no media addition showed the lowest energy consumption regarding overpotential value. In general, the Dioscorea opposita tuber flour tends to cover the electrode and reduce the activity. Moreover, the utilization of wastewater from Dioscorea opposita flour industry is still beneficial to produce hydrogen gas instead of using freshwater.

From wastewater treatment to water resource recovery: Environmental and economic impacts of full-scale implementation

To reduce greenhouse gas emissions and promote resource recovery, many wastewater treatment operators are retrofitting existing plants to implement new technologies for energy, nutrient and carbon recovery.In literature, there is a lack of studies that can unfold the potential environmental and economic impacts of the transition that wastewater utilities are undertaking to transform their treatment plants to water resource recovery facilities (WRRFs). When existing, literature studies are mostly based on simulations rather than real plant data and pilot-scale results. This study combines life cycle assessment and economic evaluations to quantify the environmental and economic impacts of retrofitting an existing wastewater treatment plant (WWTP), which already implements energy recovery, into a full-scale WRRF with a series of novel technologies, the majority of which are already implemented full-scale or tested through pilot-scales. We evaluate five technology alternatives against the current performance of the WWTP: real-time N2O control, biological biogas upgrading coupled with power-to-hydrogen, phosphorus recovery, pre-filtration carbon harvest and enhanced nitrogen removal. Our results show that real-time N2O control, biological biogas upgrading and pre-filtration lead to a decrease in climate change and fossil resource depletion impacts. The implementation of the real-time measurement and control of N2O achieved the highest reduction in direct CO2-eq emissions (-35%), with no significant impacts in other environmental categories. Biological biogas upgrading contributed to counterbalancing direct and indirect climate change impacts by substituting natural gas consumption and production. Pre-filtration increased climate change reduction by 13%, while it increased impacts in other categories. Enhanced sidestream nitrogen removal increased climate change impacts by 12%, but decreased marine eutrophication impacts by 14%. The reserve base resource depletion impacts, however, were the highest in the plant configurations implementing biological biogas upgrading coupled with power-to-hydrogen. Environmental improvements generated economic costs for all alternatives except for real-time N2O control. The results expose possible environmental and economic trade-offs and hotspots of the journey that large wastewater treatment plants will undertake in transitioning into resource recovery facilities in the coming years.