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Artificial Intelligence (AI) techniques, such as Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), and dimensional analysis-based empirical equations (DAEEs), can estimate scour depth around bridge piers. AI's accuracy depends on various architectures, while DAEEs' performance depends on experimental data. This study evaluated the performance of AI and DAEEs for scour depth estimation using flow velocity, depth, size of bed sediment, critical approach velocity, and pier width. The data from a smooth rectangular (20 m × 1 m) flume and a high-precision particle image velocimetry to study the flow structure around the pier - width: 1.5 – 91.5 cm evaluated DAEEs. Various ANNs (5, 10, and 15 neurons), double layer (DL) and triple layers (TL), and different ANFIS settings were trained, tested, and verified. The Generalized Reduced Gradient optimization identified the parameters of DAEEs, and Nash–Sutcliffe efficiency (NSE) and Mean Square Error (MSE) evaluated the performance of different models. The study revealed that DL ANN-3 with 10 neurons (NSE = 0.986) outperformed ANFIS, other ANN (ANN1, ANN2, ANN4 & ANN5) models, and empirical equations with NSE values between 0.76 and 0.983. The study found pier dimensions to be the most influential parameter for pier scour. [ABSTRACT FROM AUTHOR]

Fractal dimension represents the geometric irregularity of an object with respect to the underlying space and is used for several characterizations. The divider method and the box counting method are two classical methods to compute the fractal dimension of fractals, coastlines, natural objects and other complex systems. In this work, we present a novel, extremely efficient algorithm based on the fractal interpolation function (FIF) method for estimating the fractal dimension of coastlines and for reconstructing the coastline geometry. The algorithm is implemented for the coastline of the Kingdom of Saudi Arabia (KSA) as a case study. For validating the accuracy of the proposed algorithm in estimating the fractal dimension we compare our results with those obtained using the divider and the box-counting method. We also reconstruct the coastline geometry of KSA using our algorithm which generates functions (interpolants) that matches the coastline geometry very accurately. Numerical simulations are obtained using a robust, parallel multi-processing library, an R - program, Python codes, a dynamic programming algorithm, binary search algorithm and the QGIS software. KSA coastline geometry, methodology and flowchart of the proposed FIF algorithm [ABSTRACT FROM AUTHOR]

Small communities and most rural settlements in the Kingdom of Saudi Arabia (KSA) store domestic wastewater in residential septic tanks and transport it to the nearest centralized wastewater treatment plant. Without a sanitary sewerage system, the residents encounter various socioeconomic and environmental challenges related to sewage collection vehicles, the production of objectionable gases, and leaking septic tanks. The present study developed a resident perception-based methodology to appraise the sustainability of a low-cost ceramic filter bioreactor-type decentralized wastewater treatment system (DWWTS) for a small community of 1300 residents (160 households) in Qassim (KSA). In addition to six demographic factors, nine indicators assessed residents' perceptions about existing and proposed wastewater management systems. A hierarchical-based system of sub-indices evaluated the three dimensions of sustainability using four environmental, nine social, and three economic indicators. The indicators translated into dichotomous questions posed to 34 respondents in the study area. The statistical analysis assessed the association of responses with the willingness to accept (WTA) the proposed DWWTS. A subjective rating scheme translated the responses into performance scores, and a fuzzy-based method aggregated the scores into sub- and top-level indices. The top of the hierarchy showed a close agreement between the resident's perception and DWWTS' sustainability. The study found that residents' knowledge about environment and resource conservation resulted in a moderately high willingness to reuse treated effluent and WTA the decentralized system. The study also showed that the economic viability of a DWWTS remained at a moderate performance level due to a low monthly waste disposal cost. The study's findings present a high potential for sustainable community-maintained DWWTS initially supported by the government. The proposed approach facilitates decision-makers working in ministries concerning water resources, environmental protection, and agricultural production in evaluating the sustainability of DWWTS for small communities in arid regions. [ABSTRACT FROM AUTHOR]

Even though water is a renewable resource, the majority of the available water on the planet is unfit for human use. Moreover, the drinkable water demand is ever-increasing as a result of rising population, urbanization, and life standards, which makes the needs for sustainable, economic, and environment-friendly treatment alternatives of utmost importance. Seawater desalination using solar stills has been proposed as a promising alternative that may help to solve drinkable water scarcity issues. In the past decades, many studies have been conducted to assess the performance of different types of solar stills aiming to enhance their productivity. Computational fluid dynamic (CFD) numerical simulation is one of the approaches that have been used recently to assess the performance of solar stills. The present study performed a systematic review and bibliometric analysis to provide a comprehensive overview of CFD numerical simulation uses as a tool to assess solar stills performance. A total of 486 publications were collected initially from different databases for the period between 2012 and 2022. The collected publications were filtered through several stages reaching 43 publications of highest significance. The collected data were analyzed descriptively, and the bibliometric mapping was presented. Furthermore, the basics and principles of CFD numerical simulation of solar stills efficiency were described and discussed. Later, the previous studies were analyzed to understand the algorithms, methods, and still types used. Finally, future research scopes and conclusions were stated. The presented knowledge in this study can help to provide a deep overview of using CFD in studying the efficiency of solar stills and inspire researchers to identify future research ways and gaps. [ABSTRACT FROM AUTHOR]

Conventional interview surveys for assessing customer satisfaction require supplementary resources and yield a low response rate. Covering fewer customers who generally face service interruptions is another limitation that hinders the identification of the root causes of failure. The survey findings might mislead the utilities by showing unrealistic satisfaction levels. Customer dissatisfaction risk subjects to the time between the complaint registration and the utility response pending full resolution of the issue. In the present research, bowtie analysis (BTA) reveals an innovative synergetic correlation between system reliability and customer satisfaction with water utilities. Using complaints reported due to service failures, the fault tree analysis (FTA) assesses the reliability of system components (pressure, water quality, and structure). On the opposite side of the bowtie, event tree analysis (ETA) evaluates the efficiency of the utility response and translates it into customer dissatisfaction risk. Exploring over 1500 registered work orders in a utility operating in British Columbia (Canada) reveals that 80% of complaints originated from structural (primarily service connections) issues. Simulating the BTA for five improvements showed that economical proactive maintenance and an efficient complaint response mechanism improve the system reliability from 58 to 86% and reduce the cumulative risk by 62%. The remaining risk reduction requires expensive improvements, e.g., source change and conventional treatment installation, which require customer approval based on willingness to pay. The study reveals that a complete bowtie analysis effectively integrates both the FTA and ETA and provides a novel customer-driven decision-support tool for water supply systems and other elsewhere applicable. [ABSTRACT FROM AUTHOR]

In addition to a wide range of socio-economic impacts, traffic congestion during the era of the COVID-19 pandemic has been identified as a critical issue to be addressed. In urban neighborhoods, the timespan of traffic congestion hazard (HTC) after the curfew lift is subjected to the commuters' decisions about home-to-shopping center departures. The decision for departing early or late for shopping depends on both the internal (commuter related) and external (shopping center related) factors. The present study developed a practical methodology to assess the HTC period after the curfew timings. An online questionnaire survey was conducted to appraise the commuters' perception about departure time and to assess the impact of eight internal (family size, involvement in other activities, nature of job, education level, age, number of vehicles, number of children, and availability of personal driver) and three external (availability of shopping center of choice in near vicinity, distance to shopping center, and size of the city) factors on their decision. With an acceptable 20% response rate, Chi-square and Cramer's V tests ascertained family size and involvement in other activities as the most significant internal factors and availability of shopping center of choice as the primary external factor. Age, number of children, and size of the city influenced to some extent the commuters' decisions about early or delayed departure. Large associations were found for most of the factors, except education level and availability of drivers in a household. Fuzzy synthetic evaluation (FSE) first segregated the commuters' responses over a four level-rating system: no delay (0), short delay (1), moderate delay (3), and long delay (5). Subsequently, the hierarchical bottom-up aggregation effectively determined the period of highest traffic congestion. Logical study findings revealed that most (about 65%) of the commuters depart for shopping within 15 min after the curfew lift, so HTC in the early part (the first one hour) of the no curfew period needs attention. The traffic regulatory agencies can use the proposed approach with basic socio-demographic data of an urban neighborhood's residents to identify the HTC period and implement effective traffic management strategies accordingly. [ABSTRACT FROM AUTHOR]

Limited knowledge on the water–energy–carbon nexus of water supply systems (WSSs) with brackish groundwater sources in arid regions exists to date. In addition, the large amount of fossil-fuel energy utilized by treatment processes generating a significant amount of carbon emissions remains a challenge for the municipalities in Saudi Arabia to meet long-term sustainability goals. To achieve Saudi Arabia Vision 2030's target of sustainable cities with reduced CO2 emissions, the present study aimed to analyse the water–energy–carbon nexus for WSSs and propose mitigation measures for reducing energy and carbon footprints from both the water management and treatment technologies perspectives. The detailed energy consumption data for three main components (source extraction, water treatment, and conveyance and distribution) of the main WSS, serving the 600,000 population of Buraydah City (Qassim, Saudi Arabia), was obtained from the concerned municipality. The city water treatment plant removes naturally occurring iron, TDS, and radionuclides in the source water with the help of ion detention, oxidation, sand filtration, ultrafiltration, reverse osmosis, chlorination, and backwash water management. The study found that the treatment facility consumes around half of the total system's energy (131,122 kWh/day); while, with deep confined aquifer (>600 m) and an average water loss of 8%, conveyance and distribution (34%) and source extraction (18%) are consistent with the reported literature. With oil-driven energy, carbon emissions were found to be 10.26, 27.18, and 19.72 million tons CO2 eq/year for source extraction, water treatment, and conveyance and distribution, respectively. The reverse osmosis process, with higher energy consumption—1.1 kWh/m3 of treated water—than the global average, consumes most (88%) of the treatment plant's energy and thus needs effective energy management practices. Moving to renewable (solar and wind-driven) sources, subject to a detailed life cycle analysis, can achieve significant energy and associated carbon emission reductions. To sustainably meet the water demand of the growing population in arid regions, the study also suggests raising the awareness of the public about how water conservation can control CO2 emissions, proactive maintenance of aging infrastructure, and increasing rainwater and treated wastewater reuse, to enhance the operational life of existing treatment facilities. [ABSTRACT FROM AUTHOR]

Water utilities in arid regions deal with multifaceted issues of natural groundwater contamination, high treatment costs, and low water rates. These utilities rely on intermittent supplies resulting in numerous water quality failures at source, treatment, distribution, and in-house plumbing systems. The present research presents an inclusive risk assessment methodology for managing water quality from source to tap. Three-year monitoring data for turbidity, TDS, pH, iron, ammonia, nitrates, residual chlorine, Coliform group, E. coli, and Fecal Streptococci identified the root causes of failures. The cause-effect relationships in the form of a fault tree were solved using multiple failure modes and effect analysis (FMEA) to handle both the Boolean operations. The fuzzy sets addressed the uncertainties associated with data limitations in calculating exceedance probabilities (Pe) and vagueness in expert opinion for subjective evaluation of severity and detectability. The methodology was applied on a smaller system serving 18,000 consumers in Qassim, Saudi Arabia. Potable supplied water underwent reoccurrence of TDS (Pe = 20%), turbidity (Pe = 10%), and Fe (Pe = 2%) failures in distribution that further increased up to 44%, 33%, and 11% at the consumer end. The Pe for residual chlorine failure soared up to 89%. Economic controls reduced the cumulative risk to 50%, while the shift to continuous supply can limit the remaining failures under the acceptable risk. The framework will help utilities manage water quality in intermittent systems from source to tap in Saudi Arabia, the Gulf, and elsewhere. [ABSTRACT FROM AUTHOR]

Membrane fouling is one of the main factors that hinders the wide application of ultrafiltration (UF) processes. Limited research on the influence of temperature condition on reversible and irreversible natural organic matter (NOM) fouling has been conducted. Fouling and cleaning of a submerged polymeric UF with different NOM components were examined at 5°C, 20°C, and 35°C. Fouling was evaluated using the modified fouling index-UF (MFI-UF) and unified membrane fouling index (UMFI) indices, analysis of cake layer properties, and specific flux recovery. Results showed that fouling increased by 15%–35% when water temperature decreased from 20°C to 5°C, whereas fouling decreased by 15%–25% when the temperature increased to 35°C. The UMFIf fouling order was consistent across all temperature conditions with the NOM mixture and bovine serum albumin (BSA) fouling more severely than the alginate and humic acid. The UMFI and MFI-UF exhibited the same fouling order and can be used in complement to each other. BSA was found to be more sensitive to temperature changes and irreversibly fouling more than humic acid and alginate. The ratio of irreversible to reversible fouling (UMFIhir/UMFIhr) increased by 15%–25% from 35°C to 20°C and by 30%– 40% from 20°C to 5°C indicating the need for altered cleaning strategies at cold water conditions. [ABSTRACT FROM AUTHOR]

Fouling research with polymeric membranes has demonstrated that various natural organic matter (NOM) fractions contribute differentially to membrane fouling behavior. However, limited studies exist analyzing the sensitivity of the MFI-UF to be used as a tool to differentiate NOM fouling components. The results here indicate that MFI-UF is a suitable tool for assessing NOM fouling. Specifically, NOM fouling potential was in the order of organic proteins (as BSA), polymers (alginate), and humic acid, respectively. Further, a mixed solution containing BSA, alginate and humic acid fouled similarly to the BSA solution indicating the high fouling potential of organic proteins in membrane systems. The MFI-UF value was found to increase by > 30% with increasing pressure (1–3 bar) and decreasing temperature (35°C–5°C). The filtered water volume was found to correlate with the MFI-UF values indicating the dependency of the method on testing conditions. Incorporating water viscosity and pressure values against normalized conditions (20°C and 2 bar) with the standard MFI-UF equation was found to be useful to estimate MFI-UF values at variable operating conditions, thus, enhances the potential application range of MFI-UF as a fouling index for NOM. [ABSTRACT FROM AUTHOR]

Management of backwash water (BW) generated from sand filtration of groundwater naturally contaminated with iron (Fe), manganese (Mn), and radium (Ra) remains a challenge worldwide. The present study investigated the effectiveness of a low-cost clay ceramic filter for BW recycling along with residual sludge utilization for Ra removal from BW. A 15 day continuous ceramic filtration process operated at a constant flux of 2000 L/m2/d (83 LMH) showed 99% removal of Fe, Mn, and turbidity. The treated BW was found suitable for recycling back to the sand filters. Subsequently, the residual sand filter backwash sludge (BS) was collected, characterized by scanning electron microscopy (SEM) and X-ray diffraction, and examined as a potential adsorbent to the Ra. Results showed that the sludge constituted heterogeneous basic elements, with higher percentages of iron and manganese oxides. The sludge can be classified as typical mesoporous and poorly crystalline minerals consisting primarily of quartz and Mn2O3. Over 60% of Ra from the initial 2.1 bq/L could be removed by sludge in 30 min at neutral pH. The adsorption kinetics of sludge described well by the pseudo-second order model and Ra adsorption on the sludge were mainly controlled by chemisorption rate-controlling steps, intraparticle diffusion, and external mass transfer processes. Treatment of BW by low-cost clay ceramic filters and the utilization the BS for Ra removal would be a sustainable sand filter BW management practice. [ABSTRACT FROM AUTHOR]