Water Utility Managers Research Articles

Optimization of Water Distribution System Operation with Multiple Tanks and Pumps: Application for Asmara, Eritrea’s Water Supply System

Pump energy consumption is the major operational cost of water distribution systems (WDS). Defining better pump operation policies can reduce the cost and the enhance service provided. The nonlinear hydraulic behavior of WDS makes the pump scheduling problem complex, especially in large WDS in which several tanks and pumping stations coexist. The nonlinear hydraulic behavior of WDS is captured using numerical simulation. However, the required energy calculations were computed from the flow rate and head increase after the pumping stations. There are many optimization algorithms for the reduction of the operational cost. The majority of these algorithms are applied to hypothetical case studies with reduced feasible solution spaces. When the search space becomes large and many alternatives (pumps combinations) are possible, most of the proposed algorithms fail. Thus, the application of these algorithms in real case studies is very limited, and water utility managers still rely on human expertise to schedule pump operation rather than on automatic scheduling. This paper proposes the use of a genetic algorithm for large WDS with a many tanks and pumps. Offline hydraulic simulations allow the definition of water level bounds in the tanks. The combination of the pumps is determined a priori and the optimization algorithm is run in a reduced search space. These preparations allow the genetic algorithm to identify quickly the optimal policy and reduce the cost of energy consumption. The proposed framework was applied to the WDS of the city of Asmara, Eritrea, with 12 tanks and 9 pumping stations. The results showed that the tanks controlled by pumps worked perfectly and the water level was kept within the defined ranges. However, the constraints were not fulfilled for uncontrolled tanks. This application showed the limitations of methodologies proposed in the literature, and it is suggested that further techniques be found to schedule the pump working policies of large WDS while reducing the violations of constraints.

Incorporation of COVID-19-Inspired Behaviour into Agent-Based Modelling for Water Distribution Systems’ Contamination Responses

Drinking water contamination events in water networks are major challenges which require fast handling by the responsible water utility manager agent, and have been explored in a variety of models and scenarios using, e.g., agent-based modelling. This study proposes to use recent findings during the COVID-19 pandemic outbreak and draw analogies regarding responses and reactions to these kinds of challenges. This happens within an agent-based model coupled to a hydraulic simulation where the decision making of the individual agents is based on a fuzzy logic system reacting to a contamination event in a water network. Upon detection of anomalies in the water the utility manager agent places mobile sensor equipment in order to determine endangered areas in the water network and warn the consumer agents. Their actions are determined according to their social backgrounds, location in the water network and possible symptoms from ingesting contaminated water by utilising a fuzzy logic system. Results from an example application suggest that placing mobile equipment and warning consumers in real time is essential as part of a proper response to a contamination event. Furthermore, social background factors such as the age or employment status of the population can play a vital role in the consumer agents’ response to a water event.

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.

Psychosocial determinants of household adoption of water-efficiency behaviors in Tehran capital, Iran: Application of the social cognitive theory

Urban settings are particularly vulnerable to water scarcity, where ensuring future water security has become a critical challenge for water utility managers, especially in semi-arid and arid areas. Residential water conservation behaviors are of paramount importance to meet water security in urban areas. However, promoting residential water conservation behaviors among urban households is greatly dependent on their voluntary acceptance and involvement. Hence, exploring the psychosocial factors that underlie residential water conservation behaviors plays a substantial role in devising interventional practices aimed at households' behavioral changes. The present study was conducted by using the social cognitive theory aimed to understand the psychosocial determinants that underlie the household adoption of water-efficiency behaviors in Tehran capital, Iran. Data were collected using a cross-sectional survey method (N = 820) among Tehran's households. The key results of structural equation modeling were: (1) The social cognitive theory framework accounted for 61% and 41% of the variance of behavioral intentions and behaviors, respectively; (2) Self-efficacy was the most potent determinant of behavioral intentions while behavioral intentions were the strongest predictor of behaviors; (3) Self-efficacy and outcome expectancies had indirect significant effects on behaviors. Based on the findings, several policy implications were proposed to policymakers to promote residential water-efficiency behaviors.

Evaluation and comparison of centralized drinking water softening technologies: Effects on water quality indicators

Drinking water softening is often implemented to increase consumer convenience e.g. by reducing lime scaling and soap use. Softening reduces hardness, but changes also the overall mineral composition of the water, depending on the technology. A broad spectrum of effects from softening has to be considered in relation to e.g. health and corrosion when selecting softening technology and design, otherwise adverse effects may be overlooked in the attempt to increase consumer convenience. We here provided a framework for evaluating softening technologies using water quality indicators for lime scaling, soap use, corrosion, human health, taste and removal of contaminants. None of the evaluated softening technologies scored positive on all the included water quality indicators. Precipitation technologies (lime/soda-ash softening and pellet softening) reduce the predicted copper and lead release, but negatively affect stainless steel corrosion expressed by the Larson Ratio. Pellet softening does not remove magnesium, which may limit the achievable softening depth, but maintains a protective effect against cardio-vascular diseases. Strong-acid cation exchange is not expected to affect the included corrosion indicators, whereas the effects from membrane separation (nanofiltration and reverse osmosis) and weak-acid cation exchange depend on the specific source water and process design. All the evaluated technologies reduce hardness, calcium carbonate precipitation potential (CCPP) and atopic eczema, but have potential adverse effects on dental carries (expressed by DMF-S). Our framework provides a better understanding of softening and can prepare water utility planners and managers for better decisions that balance the positive and adverse effects from drinking water softening.

Using molecular detection for the diversity and occurrence of cyanobacteria and 2-methylisoborneol-producing cyanobacteria in an eutrophicated reservoir in northern China

Aquatic ecosystems and drinking water supply systems worldwide are increasingly affected by taste and odor episodes. In this study, molecular approaches including next-generation sequencing (NGS) and quantitative polymerase chain reaction (qPCR) were used to study the diversity and dynamics of cyanobacteria and 2-methylisoborneol (2-MIB)-producing cyanobacteria in Yuqiao Reservoir, a eutrophicated drinking water reservoir in Tianjin city, northern China. NGS revealed that the entire cyanobacterial community consisted of 16 genera, with Planktothrix (28.8%), Pseudanabaena (18.4%), Cylindrospermosis (7.8%), and Microcystis (7.6%) being the dominant genera, while microscopic examination identified only eight cyanobacterial genera. NGS of the 2-MIB synthesis gene revealed that Pseudanabaena and Planktothricoides were the main 2-MIB producers, with Pseudanabaena being dominant. This finding demonstrated that NGS can identify 2-MIB producers quickly and accurately and it can thus play an important role in the practical monitoring of aquatic ecology. The qPCR test showed 2-MIB synthesis gene with 4.27 × 106 copies/L to 2.24 × 109copies/L occurring at the three sampling sites. The mic gene copy number increased before the 2-MIB concentration increased, indicating that forecasting role in dealing with the 2-MIB concentration by gene copy number. Predicting 2-MIB by qPCR in the field must be verified with additional studies. The combination of NGS and qPCR can be an even more comprehensive method to provide early warning information to managers of reservoirs and water utilities facing taste and odor incidents. This is the first amplicon NGS dataset based on 2-MIB gene to study the diversity and dynamics of 2-MIB-producing cyanobacteria.

Optimizing NOM Removal: Impact of Calcium Chloride

Understanding the character of natural organic matter (NOM) and assessing its impact on water quality is paramount for managers of catchments and water utilities. For drinking-water producers, NOM affects disinfectant demand and the formation of by-products which can have adverse health effects. NOM content in raw waters also has an impact on water treatment processes by increasing required coagulant dosages, reducing the effectiveness of adsorption processes and fouling membrane systems. This study investigated the effects of calcium chloride (CaCl2) as a co-coagulant in Al3+ and Fe3+ assisted coagulation, flocculation and sedimentation processes for NOM-removal from raw water collected from Lake Bolmen, in southern Sweden. Jar tests were conducted at Ringsjö Water Works (WW), a surface water treatment plant (WTP), to investigate the potential reduction in primary coagulants aluminum sulphate (Al2(SO4)3) and ferric chloride (FeCl3). This work shows that CaCl2 can, in certain situations, reduce the need for primary coagulants, which would reduce the environmental impact and costs associated with primary coagulant consumption.

Spatial simulation of forest road effects on hydrology and soil erosion after a wildfire

AbstractPost‐fire catchment and water utility managers throughout the world use predictive models to estimate potential erosion risks to aid in evaluating downstream impacts of increased runoff and erosion, and to target critical areas within a fire for applying mitigation practices. Erosion prediction can be complicated by forest road networks. Using novel GIS technology and soil erosion modelling, this study evaluated the effect of roads on surface runoff, erosion and sediment yields following a wildfire and determined that the predictive models were providing reasonable results. The GeoWEPP model was used to simulate onsite erosion and offsite sediment delivery before and after fire disturbance using a 2‐m resolution DEM as the terrain layer. Erosion rates in excess of 4 Mg ha−1 year−1were predicted mainly from steep moderate and high severity burn areas. Roads influenced surface runoff flow path distributions and sub‐catchment delineations, affecting the spatial distribution of sediment detachment and transport. Roads tended to reduce estimated erosion on slopes below the roads but increases in erosion rates were estimated for road fillslopes. Estimated deposition amounts on roads and in sediment basins were similar to measured amounts. The results confirm that road prisms, culverts and road ditches influence sedimentation processes after wildfire, and they present opportunities to detain eroded sediments.

Data fusion to monitor remineralisation of desalinated groundwater in calcite contactors

The emergence of organic micropollutants in surface waters and even groundwater and increasing salination in river delta areas, drives water utility managers towards adoption and application of advanced and robust barriers in drinking water production like reverse osmosis (RO) filtration. However, water produced by RO, called permeate, contains hardly any minerals, is corrosive and bitter in taste. Hence, remineralisation is needed to improve the permeate water quality and comply with (Dutch) drinking water regulation. In order to test the performance of remineralisation using limestone (calcite) filtration, a pilot-scale filter has been set up and connected to an RO filtration system that treats anaerobic groundwater and equipped with on-line sensors for pH, conductivity and carbon dioxide. The degree of (re)mineralisation was tested at different flow rates, a smaller calcite grain size and with a lower temperature than previous studies. The pilot shows that the degree of remineralisation performance can be monitored on the basis of a few on-line sensors and a model that describes the dissolution of calcite.

The Velocity of Crisis: How the Pandemic Creates Opportunities for Change.

The Velocity of Crisis: How the Pandemic Creates Opportunities for Change.

Evaluating the policy of listening to customer claims in a drinking water utility using fuzzy-AHP approach and WASPAS method

Abstract The objective of this work is to develop a decision support methodology intended for drinking water utility managers in order to support them in the challenge of achieving better performance in the management of the customer area. This methodology requires the prior collection of data for the identification of registered claims. Subsequently, an evaluation of the performance of the customer area defined by the objective ‘Better listening to customer claims’ will be carried out; this requires the structuring of the objective in a hierarchy based on indicators and the adoption of two adequate decision support tools, a fuzzy-AHP for weighting the elements and WASPAS for calculating the performance of the objective. An application is carried out on the water utility of the Wilaya of Bejaia (Algeria). The data collection enabled the identification of 19 types of claims divided into three aspects. The combination of fuzzy-AHP and WASPAS allowed assessment of the performance of the objective during the period 2014–2018 and to make a judgment on the national policy established. The results are satisfactory. Progress has been made in claims management, but the major difficulty lies in the claims processing relating to the quantitative aspect.

AWWA Water Science Author Spotlight

Having recently published an article in AWWA Water Science, Jennifer Biddle answered some questions from its editor-in-chief Kenneth L. Mercer about the research. Autonomy Matters: Insights From U.S. Water Utility Managers on Governance Structure Jennifer stands near a horse barn, where she is celebrating her nine-year-old's shared love of horses. As a child, I loved playing in the creek in our suburban neighborhood, catching salamanders and tadpoles with my brother. We would observe them for hours. After the highway bypass was built and residential development exploded, the woods around the creek were cleared and the land paved over. We watched the nature of our creek change from thriving ecosystem to an eroded drainage way. The water became murky, the rocks were covered with sediment, and the creatures we loved disappeared. That was my first lesson on how land use affects water quality. After college I interned at an environmental consulting firm, where I performed water quality analyses for environmental impact assessments. That experience taught me the value of Clean Water Act regulations. Graduate school helped me pair the two, and my research looks at the confluence of science, public policy, and public administration, evaluating governance factors that build or block adaptive capacity for resilience in linked socio-ecological systems. Jennifer kayaks at the mouth of the Pamlico River in Goose Creek State Park in North Carolina. © 2015 Sara Marriott. I am fortunate to have learned from many incredible teachers and mentors over the years. One of the most impactful pieces of advice for me was to follow my interests and trust the process. I switched research topics halfway through my tenure track, and many colleagues encouraged me to wait until I had received tenure to follow my research interests. My mentor encouraged me to pursue the research I was passionate about and to trust the process of diligent research toward the goal of getting articles published. Taken in June 2016 at the AWWA Annual Conference & Exposition in Chicago, Jennifer cools off in the Polk Bros. Foundation fountain. Our AWWA Water Science article is part of a larger study (stay tuned . . .) to understand which governance features are important for improving water utility sustainability. Our hope is that this knowledge helps inform management decisions about where to invest resources to provide water utilities the capability to adapt to changing conditions. We are really fortunate to live on the coast, with easy access to the river, marshes, and the sea. I love to swim, kayak, and play in and near the water. I expose my children to all the wonders of the aquatic environment so they can appreciate and love it as much as I do. To learn more about Jennifer's research, visit the article online at https://doi.org/10.1002/aws2.1140.

The energy – pressure nexus in the water supply system

Abstract Due to the importance of overall sustainable development, efficient energy management should be as significant as water resource management within every water supply system. The pressure reduction, as a measure for loss reduction, not only guarantees less leakage but also minimizes energy consumption. The relationship between energy consumption and pressure in water supply systems has been the subject of many previous studies, mainly based on measurements in real systems. However, a methodology for beforehand assessment of energy savings which occur due to the pressure reduction, has not been proposed yet. The paper proposed a method for the assessment of energy savings in relation to pressure reduction, implemented it on the hypothetical water supply system and verified it on the real system. Results led to the conclusion that the proposed methodology can be considered as a successful tool for better energy and water management. It enables water utility management to estimate energy saving in water supply system in advance, based on the hydraulic model of the system.

Implications of SARS-CoV-2 on current and future operation and management of wastewater systems.

While researchers have acknowledged the potential role of environmental scientists, engineers, and industrial hygienists during this pandemic, the role of the water utility professional is often overlooked. The wastewater sector is critical to public health protection and employs collection and treatment system workers who perform tasks with high potential for exposures to biological agents. While various technical guidances and reports have initially provided direction to the water sector, the rapidly growing body of research publications necessitates the constant review of these papers and data synthesis. This paper presents the latest findings and highlights their implications from a water and wastewater utility operation and management perspective. PRACTITIONER POINTS: Extrapolation from SARS-CoV-1 and MERS-CoV, as well as other surrogates, has helped predicting SARS-CoV-2 behavior and risk management. Data from treated wastewater effluent suggest that current processes are sufficient for SARS-CoV-2 control. Scientific evidence supports thepossibilityof fecal-oral transmission for SARS-CoV-2. Limited evidence supports the potential survival of infective SARS-CoV-2 on surfaces and in aerosols and the efficacy of control measures at reducing transmission. Protective practices and PPE can protect workers from SARS-CoV-2 and other pathogens found in wastewater.

Aligning stakeholder interests: How ‘appropriate’ technologies have become the accepted water infrastructure solutions for low-income areas

Service differentiation and the use of "appropriate technologies" are often presented as alternative approaches to providing water service to low-income areas. Service differentiation allows water service providers to manage the risks associated with service expansion to these areas. We argue that rather than a choice of the service provider alone, the decision for service differentiation should be seen as a consensus between different actors in the water services sector. A review of secondary data, and semi-structured interviews with diverse stakeholders in three Kenyan cities, show that managers of water utilities also choose these strategies because they appeal to and align with the interest of donors, governments, sector organisations, and alternative providers.

Urban Water Demand Prediction for a City That Suffers from Climate Change and Population Growth: Gauteng Province Case Study

The proper management of a municipal water system is essential to sustain cities and support the water security of societies. Urban water estimating has always been a challenging task for managers of water utilities and policymakers. This paper applies a novel methodology that includes data pre-processing and an Artificial Neural Network (ANN) optimized with the Backtracking Search Algorithm (BSA-ANN) to estimate monthly water demand in relation to previous water consumption. Historical data of monthly water consumption in the Gauteng Province, South Africa, for the period 2007–2016, were selected for the creation and evaluation of the methodology. Data pre-processing techniques played a crucial role in the enhancing of the quality of the data before creating the prediction model. The BSA-ANN model yielded the best result with a root mean square error and a coefficient of efficiency of 0.0099 mega liters and 0.979, respectively. Moreover, it proved more efficient and reliable than the Crow Search Algorithm (CSA-ANN), based on the scale of error. Overall, this paper presents a new application for the hybrid model BSA-ANN that can be successfully used to predict water demand with high accuracy, in a city that heavily suffers from the impact of climate change and population growth.

Assessment of actions to tackle the shortages of water in La Paz, Bolivia

Abstract Water scarcity is a persistent problem in diverse regions of the world. This study focuses on the extreme scarcity of water affecting La Paz, a municipality in the west of Bolivia. The intense drought of the last few decades and the inadequate management of water utilities have impacted several factors. Within this context, this study identified that establishing efficient water resource management is essential to guarantee social welfare. The researchers analyzed the scarcity of water in La Paz by using the Strategic Choice Approach, which is a problem structuring method based on a strategic process that takes different types of uncertainty into account. The results of this study revealed decision actions and uncertainties in two categories: the present and the future. The outputs enabled a strategic plan to be drawn up that tackles the scarcity of water responsibly and equitably. Innovation and investment in ways to reuse water are fundamental to developing a responsible solution.

A novel dynamic hydrant flushing framework facilitated by categorizing contamination events

ABSTRACT Security of water distribution systems is of highest importance to public health. In this study, a novel dynamic hydrant flushing strategy is developed to remove the injected contamination mass in the shortest possible time after being detected by the sensors. The coupled EPANET-IHS simulation-optimization model is developed to determine the hydrant flushing strategies (the hydrant sets and their opening/closing time). This allows water utility managers to utilize the hydrants instantly after the sensor alarm with no need for excessive investigations, which enhances the flushing effectiveness. Developed based on thousands of contaminant injection scenarios (contamination events), the proposed hydrant flushing strategies are reliable to remove any injected contamination mass. Moreover, the operation of hydrant sets is dynamically validated by closing/opening of hydrants throughout the total hydrant flushing duration, which enables the model to flush up to more 20%. The methodology is examined on the mid-sized WDS of Mesopolis city.

Beyond the trends: The need to understand multiannual dynamics in aquatic ecosystems

Beyond the trends: The need to understand multiannual dynamics in aquatic ecosystems

The Upshot of Autonomy and Efficiency of Urban Water Service Providers inUganda and Tanzania

The theoretical and empirical debate on the effect of managerial autonomy on the efficiency of urban utilities is still ongoing, yet limited research has been conducted in the water sector in developing countries. To address the gap, this paper gives empirical evidence on the effect of managerial autonomy on the efficiency of urban water service providers in Uganda and Tanzania. Using the managerial autonomy index and Data Envelopment Analysis (DEA), information from performance and management contracts, utility annual financial reports, partnership deed agreements, water policy statements, and results of 66 respondents was used to determine the level of managerial autonomy and efficiency in the 30 Decision Making Units (DMUs) of NWSC in Uganda and DAWASCO in Tanzania. The effect of managerial autonomy on efficiency was determined using Tobit regression analysis. The results show the mean managerial autonomy level of 47% implying that Head Office (HO) of water utilities has given limited autonomy to the different Decision Making Units (DMUs). Most of the DMUs have no or limited autonomy on procuring assets for their units, entering loan agreements, approving the annual report, and determining staff compensation. The fully efficient towns (1.00) are four and the mean efficiency level is 0.63. The Tobit regression model indicates that the adoption of managerial autonomy significantly (Prob>chi2 = 0.0006) contributes to efficiency. The findings indicate a high likelihood of managerial autonomy causing a change in the efficiency of urban water utilities. The position that an increase in managerial autonomy will cause the likelihood for technical efficiency to decrease, could be expected in the event that the principal (HO) who grants autonomy may not keenly and continuously supervise and monitor the activities of the agent (DMU). Urban water utility managers should put in place an appropriate structural framework to govern the relationship between the water utility HO and the DMU. Besides this, the utility head office should delegate decision making powers to the DMUs based on a clear framework.