Assessment of Wastewater Reuse in Kuwait and Its Impact on Amounts of Pollutants Discharged into the Sea

Kuwait has recently implemented a vigorous campaign that aims to reclaim and reuse all treated wastewater in an at- tempt to alleviate water scarcity problem and to preserve seawater quality. This paper assesses the present status of wastewater treatment, reclamation and reuse in Kuwait, and discusses the impact of wastewater reuse on the amounts of pollutants discharged into the sea. Through analysis of the historical records of the wastewater treatment plants, it has been found that reuse of reclaimed wastewater in Kuwait has greatly reduced the amounts of pollutants discharged into the sea. Results showed that more than 50% reduction in volumes of wastewater discharged into the sea had been achieved from year 2000 to year 2010. However, this study has predicted that the amounts of wastewater discharged into the sea will start increasing again by the year 2020 due to shortages of storage capacity for reclaimed wastewater and due to the limitation of wastewater reuse applications to basically agricultural and landscape irrigations. In contrary, the on-going works and future plans of the Ministry of Public Works (MPW) are expected to overcome this problem and lead to a zero discharge of wastewater into the sea.

Greywater reuse as a key enabler for improving urban wastewater management

Sustainable water management is essential to guaranteeing access to safe water and addressing the challenges posed by climate change,urbanization,and population growth.In a typical household,greywater,which includes everything but toilet waste,constitutes 50e80%of daily wastewater generation and is characterized by low organic strength and high volume.This can be an issue for large urban wastewater treatment plants designed for high-strength operations.Segregation of greywater at the source for decentralized wastewater treatment is therefore necessary for its proper management using separate treatment strategies.Greywater reuse may thus lead to increased resilience and adaptability of local water systems,reduction in transport costs,and achievement of fit-for-purpose reuse.After covering greywater characteristics,we present an overview of existing and upcoming technologies for greywater treatment.Biological treatment technologies,such as nature-based technologies,biofilm technologies,and membrane bioreactors(MBR),conjugate with physicochemical treatment methods,such as membrane filtration,sorption and ion exchange technologies,and ultraviolet(UV)disinfection,may be able to produce treated water within the allowable parameters for reuse.We also provide a novel way to tackle challenges like the demographic variance of greywater quality,lack of a legal framework for greywater management,monitoring and control systems,and the consumer perspective on greywater reuse.Finally,benefits,such as the potential water and energy savings and sustainable future of greywater reuse in an urban context,are discussed.

Advancements in adsorption and photodegradation technologies for Rhodamine B dye wastewater treatment:fundamentals,applications,and future directions

Organic dye pollutants present in wastewater pose a significant global challenge.Among pollutants,the synthetic dye Rhodamine B(RB)stands out due to its non-biodegradable nature and associated neurotoxic,carcinogenic,and respiratory irritant properties.Extensive research has been conducted on the efficacy of adsorption and photodegradation techniques for the removal of RB from wastewater.While adsorption and advanced oxidation processes(AOPs)have gained considerable attention for their effectiveness in recent years,the underlying behaviors and mechanisms of these technologies remain incompletely understood.Therefore,a comprehensive of recent research progress in this domain is imperative to clarify the basics and present the up-to-date achievements.This review provides an in-depth exploration of the fundamentals,advancements,and future trajectories of RB wastewater treatment technologies,mainly encompassing adsorption and photodegradation.This work starts with a general introduction of outlining the sources,toxicity,and diverse applicable removal strategies.Subsequently,it thoroughly examines crucial techniques within non-photochemical,photochemical,and adsorption technologies,such as UV light assisted AOP,catalyst assisted AOP,ozonation,Fenton system,electrochemical AOP,and adsorption technology.The primary objective is to furnish a broad overview of these techniques,elucidating their effectiveness,limitations,and applicability.Following this,the review encapsulates state-of-theart computational simulations pertaining to RB adsorption and interactions with clays and other adsorbents.Lastly,it delves into column adsorption of RB dye,and elucidates various influencing factors,including bed height,feed concentration,pollutant(RB)feeding or flow rate,and column regeneration.This panoramic review aims to provide valuable insights into suitable techniques,research gaps,and the applicability of nonphotochemical,photochemical,and adsorption technologies in the treatment of wastewater containing RB dye.

Digital Twins for Wastewater Treatment:A Technical Review

The digital twins concept enhances modeling and simulation through the integration of real-time data and feedback.This review elucidates the foundational elements of digital twins,covering their concept,entities,domains,and key technologies.More specifically,we investigate the transformative potential of digital twins for the wastewater treatment engineering sector.Our discussion highlights the application of digital twins to wastewater treatment plants(WWTPs)and sewage networks,hardware(i.e.,facilities and pipes,sensors for water quality and activated sludge,hydrodynamics,and power consumption),and software(i.e.,knowledge-based and data-driven models,mechanistic models,hybrid twins,control methods,and the Internet of Things).Furthermore,two cases are provided,followed by an assessment of current challenges in and perspectives on the application of digital twins in WWTPs.This review serves as an essential primer for wastewater engineers navigating the digital paradigm shift.

Performance of a Horizontal Flow Constructed Reed Bed Filter for Municipal Wastewater Treatment: The Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.

Occurrences of Glucocorticoids in Aquatic Environment and Their Removal during Wastewater Treatment

Glucocorticoids(GCs) are a group of endocrine-disrupting compounds(EDCs) frequently prescribed against various medical conditions.Recently,GCs have been shown to be effective in managing septic shock in patients infected with the 2019 novel coronavirus(COVID-19).Due to colossal consumption and potential risks to aquatic organisms,GCs have immensely attracted the focus of the scientific research community as a water pollutant.Therefore,the aim of this paper is to review the current knowledge on the occurrence of various GCs in the aquatic environment and their removal during wastewater treatment.A variety of GCs are ubiquitous in surface water,hospital wastewater,and sewage water worldwide.And the minimum concentration in volume is below 0.01 ng/L,and the maximum one is 10 000 ng/L,and enter the environment through hospital and urban wastewater discharging.Compared with natural GCs,higher risks to aquatic environments could be induced by synthetic GCs.The current activated sludge processes used in wastewater treatment plants(WWTPs) are not fully effective in eliminating GCs,some of which may further increase the risk of GC in the environment.In comparison with the aerobic process in WWTPs,the anaerobic and anoxic processes were found to be more efficient for GC degradation.Of the studied GCs,fluticasone propionate,clobetasol propionate,fluocinolone acetonide,and triamcinolone acetonide need more attention due to their low removal efficiencies and strong toxicity.Among the advanced treatment processes,reverse osmosis,ultraviolet irradiation,CaO_(2),and plasma could achieve significant GC activity removal while micro/ultra-filtration,chlorination,and ozonation were less efficient.

A Cradle-to-Cradle Novel Approach for Wastewater Management in Sustainable Urban Communities

Water, a valuable resource to human lives, is being abused and driven to scarcity. This scarcity is leading some countries and areas to face difficulty in accessing drinking water. As the UN recently stated “by 2050 water shortages and harder access will be reached by around 2/3rd of the world total population” [1], thus, there is a high need to treat and reuse wastewater for domestic purposes, which will lead to less reliance on fresh water as an initial water source. Greywater—defined as the water produced in domestic houses including sinks and bathroom showers, and excluding any blackwater mix which is collected from toilets—is a type of wastewater. Greywater accounts for up to 75% of the daily water produced [2] while it has fewer contaminants when compared to blackwater. This makes greywater a focal point for treatment, and reusing to conserve fresh water and approach net zero water concept. Even though the definition of greywater is the same globally, its criteria can differ from one country to another, from one building to another, or even from the same person’s usage along the day. Accordingly, several treatment methods evolved over years aiming at treating the produced greywater for reuse mainly in irrigation and toilet flushing. The objective of this paper is to demonstrate a novel net zero wastewater approach applying cradle-to-cradle concept for urban communities;while also proposing a sustainable greywater treatment technique that is environmentally friendly, cost-effective and socially acceptable.

Monitoring of 943 organic micropollutants in wastewater from municipal wastewater treatment plants with secondary and advanced treatment processes

To perform a systematic survey on the occurrence and removal of micropollutants during municipal wastewater treatment, 943 semi-volatile organic chemicals in 32 wastewater samples including influents of secondary treatments, secondary effluents and final effluents（effluents of advanced treatments）, which were collected from seven full-scale municipal wastewater treatment plants（MWTPs） in China, were examined by gas chromatography-mass spectrometry（GC-MS） coupled with an automated identification and quantification system with a database（AIQS-DB）. In total, 196 and 145 chemicals were detected in secondary and final effluents, respectively. The majority of the total concentrations（average removal efficiency, 87.0%±5.9%） of the micropollutants were removed during secondary treatments. However, advanced treatments achieved different micropollutant removal extents from secondary effluents depending on the different treatment processes employed. Highly variable removal efficiencies of total concentrations（32.7%–99.3%） were observed among the different advanced processes. Among them,ozonation-based processes could remove 70.0%–80.9% of the total concentrations of studied micropollutants. The potentially harmful micropollutants, based on their detection frequency and concentration in secondary and final effluents, were polycyclic aromatic hydrocarbons（PAHs）（2-methylnaphthalene, fluoranthene, pyrene, naphthalene and phenanthrene）, phosphorus flame retardants（tributyl phosphate（TBP）, tris（2-chloroethyl）phosphate（TCEP） and tris（1,3-dichloro-2-propyl） phosphate（TDCP））, phthalates（bis（2-ethylhexyl）phthalate（DEHP））, benzothiazoles（benzothiazole,2-（methylthio）-benzothiazol, and 2（3H）-benzothiazolone） and phenol. This study indicated that the presence of considerable amounts of micropollutants in secondary effluent creates the need for suitable advanced treatment before their reuse.

Advanced treatment of biologically pretreated coking wastewater by intensified zero-valent iron process(IZVI) combined with anaerobic filter and biological aerated filter(AF/BAF)

Experiments were conducted to investigate the behavior of the sequential system of intensified zero-valent iron process(IZVI) and anaerobic filter and biological aerated filter(AF/BAF) reactors for advanced treatment of biologically pretreated coking wastewater. Particular attention was paid to the performance of the integrated system for the removal of chemical oxygen demand(COD), ammonia nitrogen(NH3-N) and total nitrogen(TN). The average removal efficiencies of COD, NH3-N and TN were 76.28%, 96.76% and 59.97%, with the average effluent mass concentrations of 56, 0.53 and 18.83 mg/L, respectively, reaching the first grade of the national discharge standard. Moreover, the results of gas chromatography/mass spectrum(GC/MS) and gel permeation chromatography(GPC) analysis demonstrated that the refractory organic compounds with high relative molecular mass were partly removed in IZVI process by the function of oxidation-reduction, flocculation and adsorption which could also enhance the biodegradability of the system effluent. The removal efficiencies of NH3-N and TN were achieved mainly in the subsequent AF/BAF reactors by nitrification and denitrification. Overall, the results obtained show that the application of IZVI in combination with AF/BAF is a promising technology for advanced treatment of biologically pretreated coking wastewater.

Pollutants removal and simulation model of combined membrane process for wastewater treatment and reuse in submarine cabin for long voyage

A laboratory scale test was conducted in a combined membrane process （CMP） with a capacity of 2.91 m3/d for 240 d to treat the mixed wastewater of humidity condensate, hygiene wastewater and urine in submarine cabin during prolonged voyage. Removal performance of chemical oxygen demand （COD）, ammonia nitrogen （NH4^＋-N）, turbidity and anionic surfactants （LAS） was investigated under different conditions. It was observed that the effluent COD, NH4^＋-N, turbidity and LAS flocculated in ranges of 0.19-0.85 mg/L, 0.03-0.18 mg/L, 0.0-0.15 NTU and 0.0-0.05 mg/L, respectively in spite of considerable fluctuation in corresponding influent of 2120-5350 mg/L, 79.5-129.3 mg/L, 110-181.1NTU and 4.9-5.4 mg/L. The effluent quality of the CMP could meet the requirements of mechanical water and hygiene water according to the class I water quality standards in China （GB3838-2002）. The removal rates of COD, NH4^＋-N, turbidity and LAS removed in the MBR were more than 90%, which indicated that biodegradation is indispensable and plays a major role in the wastewater treatment and reuse. A model, built on the back propagation neural network （BPNN） theory, was developed for the simulation of CMP and produced high reliability. The average error of COD and NH4^＋-N was 5.14% and 6.20%, respectively, and the root mean squared error of turbidity and LAS was 2.76% and 1.41%, respectively. The results indicated that the model well fitted the laboratory data, and was able to simulate the removal of COD, NH4^＋-N, turbidity and LAS. It also suggested that the model proposed could reflect and manage the operation of CMP for the treatment of the mixed wastewaters in submarine.

Advanced Oxidation with Nanofilm Photacatalyst’S on Stainless Steel Wire as Secondary Treatment of Wastewater

In this paper,authors reported the results of wastewater treatment of discharges from sanitary facilities and laboratories from de Metropolitan Autonomous University Azcapotzalco campus in Mexico city in a pilot plant integrated with a unit of coagulation-flocculation and sedimentation of suspended particulate and multilayer filtration with sand,zeolite and anthracite that filtered particulate higher than 5 nanometer of diameter as primary treatment and advanced oxidation based in the use of hydroxyl radical through ozonation and UV Photocatalysis with zinc oxide,zinc oxide doped with silver and zinc oxide doped with zirconia as fine films photocatalysts on a US 100 stainless steel wire as secondary treatment,and finally with activated carbon adsorption as final polish.COD and ORP were evaluated after each step as representative of BOD stablished as MAC’s in Mexican regulation on wastewater effluents,obtaining values that comply with the regulation.

Advanced Treatment of Biologically Treated Chemical Comprehensive Wastewater by Nano-TiO2 Photocatalytic Oxidation

Nano-TiO2 photocatalytic oxidation was used to perform the advanced treatment of biologically treated chemical comprehensive wastewater. The effects of reaction time,nano-TiO2 dosage and initial p H of the wastewater on the removal rate of COD were tested. The GC/MS and EEM techniques were used to qualitatively analyze organic compounds in the wastewater before and after treatment. The result showed that after the biologically treated chemical comprehensive wastewater was treated by nano-TiO2 photocatalytic oxidation under the conditions of reaction time 3 h,nano-TiO2 dosage 8 g/L,and pH 8. 0,the effluent COD was 61. 9 mg/L and its removal rate was 63. 8%. Additionally,the species of organic pollutants reduced from 12 to 6. Meanwhile,the content of humic-like and fulvic-like substances dropped dramatically.

Effect of Domestic Wastewater as Co-Substrate on Biological Stain Wastewater Treatment Using Fungal/Bacterial Consortia in Pilot Plant and Greenhouse Reuse

In this study, a pilot wastewater treatment plant was used to evaluate the co-treatment of biological-staining residues and domestic wastewater under non-sterile conditions. A novel microbial consortia formed by Trametes versicolor, Trametes sp, Pleurotus ostreatus, Pseudomonas fluorescens, Pseudomonas azotoformans, Pseudomonas sp, Enterobacter xianfangensis and Bacillus subtillis was inoculated in an extended aeration type bio-reactor. The treatment units were operated during three consecutive cycles during a period of 147 h. After the last operating cycle, the concentrations of Chemical Oxygen Demand, Biochemical Oxygen Demand, Color Units, Total suspended solids, and the pH value were 1695 mg/L, 105 mg/L, 106 CU, 5), 1367 (CU), 566 mg/L (TSS) and 7.0 (pH) respectively. The reduction of pollutants load was related with the ratio of the two types of wastewater (3.5:0.5) combined to increase biodegradability, the concentration of fungi and bacteria used in the consortia (30 × 103 - 55 × 106 CUF/mL Total Fungi and 70 × 107 - 83 × 108 CFU/mL of Total Bacteria) and ligninolytic enzymes production, Laccase (13 - 96 U/L), MnP (9.8 - 39 U/L) and LiP (0.3 - 5.3 U/L). The post-treated effluent was used as irrigation water. Lolium perenne plants were watered during 60 days with post-treated effluent. The results of root weight showed that there are significant differences between the initial water and the effluent obtained after the operational cycles (p = 0.00470). The highest root weights (1 - 1.12 g) were found in plants irrigated with water obtained from the last treatment cycle.

Wastewater Treatment for Removal of Recalcitrant Compounds：A Hybrid Process for Decolorization and Biodegradation of Dyes

While conventional wastewater treatments for urban effluents are fairly routine and have proved highly effective,industrial wastewater requires more complex and specific treatments.This paper provides a technological strategy for removal of recalcitrant contaminants based on a hybrid treatment system.The model effluent containing a binary mixture of synthetic dyes is treated by a combination of a preliminary physicochemical stage followed by a biological stage based on ligninolytic enzymes produced by Phanerochaete chrysosporium.This proposal includes biosorption onto peat as pretreatment,which decreases the volume and concentration to be treated in the biological reactor,thereby obtaining a completely decolorized effluent.The treated wastewater can therefore be reused in the dyeing baths with the consequent saving of water resources.

Examination of the Level of Heavy Metals in Wastewater of Bandar Abbas Wastewater Treatment Plant

One of the main environmental pollutants is heavy metals. Due to extensive usage in industry, these metals enter biological cycle rapidly and contaminated water and soil resources rapidly. In this work, lead, copper, zinc and chromium of Bandar Abbas wastewater are examined. For this research, nine stations were set for measurement in urban level in Bandar Abbas and sampling of aforesaid metals was performed in fall and winter 2006 in these stations. After extraction and preparation operations using APDC-MIBK, samples were measured using flame atomic absorption system. According to results, concentrate of studied metals was lower than allowable standard value set by Iran environmental protection organization for agricultural purposes and sewage to ground level waters. In addition, efficiency of Bandar Abbas wastewater treatment plant to remove these metals is 40% - 70% from which highest removal is for zinc as much as 71.1% and lowest level is for copper as much as 40.5%. However, copper level was higher than allowable level for agricultural purposes in spring and summer (0.21 mg/L and 0.23 mg/L, respectively) and lower in fall and winter (0.103 mg/L and 0.098 mg/L, respectively). Furthermore, changes in concentration of metals in these stations in various seasons were measured and analyzed using one-way variance analysis and simultaneous effects of time and place on measured variables were analyzed using two-way variance analysis.

Treatment of pharmaceutical wastewater containing recalcitrant compounds in a Fenton-coagulation process

The advanced treatment using integrated Fenton＇s reaction and coagulation process was investigated in this study. Before the advancement, the pharmaceutical wastewater containing lincomycin hydrochloride was pretreated by UASB （upflow anaerobic sludge bed） and a SBR （sequencing batch reactor） process. The residual recalcitrant compounds, measured by gas chromatographymass spectrometry （GC-MS）, mainly consisted of alcohols, phenols, and nitrogenous and sulfur compounds. The experimental results indicated that when the Fenton＇s reaction was conducted at pH=3.0, H2O2CODOcr=0.27, H2O2/Fe^2＋=3：1 and 30 min of reaction time, and the coagulation process operated at a sulfate aluminum concentration of 800 mg/L and pH value of 5.0, the color and COD in the wastewater decreased by 94% and 73%, respectively; with a finale COD concentration of 267 mg/L and color level of 40 units, meeting the secondary standard of GB8978-1996 for industrial wastewater.

Mass Transfer-Promoted Fe^(2+)/Fe^(3+)Circulation Steered by 3D Flow-Through Co-Catalyst System Toward Sustainable Advanced Oxidation Processes

Realizing fast and continuous generation of reactive oxygen species(ROSs)via iron-based advanced oxidation processes(AOPs)is significant in the environmental and biological fields.However,current AOPs assisted by co-catalysts still suffer from the poor mass/electron transfer and non-durable promotion effect,giving rise to the sluggish Fe^(2+)/Fe^(3+)cycle and low dynamic concentration of Fe^(2+)for ROS production.Herein,we present a three-dimensional(3D)macroscale co-catalyst functionalized with molybdenum disulfide(MoS_(2))to achieve ultra-efficient Fe^(2+)regeneration(equilibrium Fe^(2+)ratio of 82.4%)and remarkable stability(more than 20 cycles)via a circulating flow-through process.Unlike the conventional batch-type reactor,experiments and computational fluid dynamics simulations demonstrate that the optimal utilization of the 3D active area under the flow-through mode,initiated by the convectionenhanced mass/charge transfer for Fe^(2+)reduction and then strengthened by MoS_(2)-induced flow rotation for sufficient reactant mixing,is crucial for oxidant activation and subsequent ROS generation.Strikingly,the flow-through co-catalytic system with superwetting capabilities can even tackle the intricate oily wastewater stabilized by different surfactants without the loss of pollutant degradation efficiency.Our findings highlight an innovative co-catalyst system design to expand the applicability of AOPs based technology,especially in large-scale complex wastewater treatment.

Reuse rate of treated wastewater in water reuse system

A water quality model for water reuse was made by mathematics induction. The relationship among the reuse rate of treated wastewater（R）, pollutant concentration of reused water（ Cs ）, pollutant concentration of influent（ C0）, removal efficiency of pollutant in wastewater（ E）, and the standard of reuse water were discussed in this study. According to the experiment result of a toilet wastewater treatment and reuse with membrane bioreactors, R would be set at less than 40%, on which all the concerned parameters could meet with the reuse water standards. To raise R of reuse water in the toilet, an important way was to improve color removal of the wastewater.

Study on Immobilized Algal Cells for Treatment and Recycle of Refinery Wastewater

Compared to the algal oxidation pond, treatment of wastewater using the immobilized algal cell technology has excellent effect, which not only can effectively avoid the disadvantage of oxidation pond, but can also remarkably improve the efficiency of treating system and the effluent quality. When the treating system operates umder an optimal control conditions, such as a 55% loading rate, an illumination intensity of 2500-3500 lux and a hydraulic residence time of 4 hours, the COD and ammonia nitrogen removal can reach 90%. Water after deep treatment can comply with the requirement of the refinery for the quality of recycled water.

Wastewater Treatment in the Oasis of Figuig （Morocco） by Facultative Lagoon System： Physico-Chemical and Biological Aspect

The community of Figuig is located in a desert area, east of Morocco. It is characterized by an arid climate. Part of the aquifers of the area has a high salinity which creates even worst conditions for the use of the scarce water available in the area. Therefore, it is essential to develop new water resources, especially for agriculture. For this reason, reclaiming wastewater for agricultural use is an essential strategy to increase water resources. The studied system is a wastewater treatment plant （WWTP） with stabilisation ponds; it treats a part of the wastewater of Figuig. The monitoring of the WWTP will allow to the physico-chemical and biological characterization of the treated water, and then, to verify two principal points： （1） the physico-chemical and pathogen parasites elimination; （2） the possibility of the treated water reuse in agricultural irrigation. The reductions recorded at the WWTP show a relatively preferment operation with an average decrease of 3.17 Ulog for faecal coliforms and 50-60% for organic matter. It was observed that the taxonomic density is slow in the WWTP; observed species are generally Cyanobacteria, Euglénophycea and Chlorophycea characteristic of eutrophic water sources.