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Water treatment residuals (WTRs) are by-products of the coagulation and flocculation phase ofthe drinking water treatment process that is employed inthe vast majority of water treatment plants globally.Production of WTRs are liable to increase as cleandrinking water becomes a standard resource. One ofthe largest disposal routes of these WTRs was vi...
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... processes are commonly employed ( Dassanayake et al. 2015). Where space availability permits, common dewatering strategies include the use of drying lagoons or beds (Walsh 2009). Where space is less available, dewatering via centrifugation and/or belt presses is often employed. Generally, after the full mechanical dewatering process (e.g. Fig. 2), the solids content of these WTRs increases to between 17 and 35% solids ( Dassanayake et al. 2015). However, this treatment tends to be a more energy intensive and thus more expensive process, leading to many smaller water treatment works (those without the space for drying lagoons) leaving WTRs in a liquid (2-4% solids) state. The ...
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Adsorption on a suitable adsorption material is the most frequently used methods in water treatment. In terms of plant operation, filtration (sorption) process represents a simple, effective and economical friendly method of heavy metals removal namely for the possibility of using a large scale of substances with a sorption ability - sorbents. Oxid...
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... 1−3 Although Fe-based As treatment is effective, large quantities of As-bearing hydrous ferric oxide (HFO) sludge are generated as a treatment by-product. 4 Due partly to negative perceptions of As, this sludge has traditionally been viewed as a disposal challenge rather than a resource, 5,6 despite the often high content of co-occurring phosphate (P), which binds effectively to HFO surfaces, 7 and the potential to reuse the reactive HFO sorbent. 8 Consequently, unsustainable and unsafe disposal methods are applied for As-bearing sludge, including landfilling in high-income areas and open disposal to surface waters and soils in low-income areas. ...
... For all sludges, As K-edge EXAFS analysis indicated As was present initially as arsenate (As(V)) bound to Fe(III) precipitates. 8 High NaOH concentrations thus favor the formation of fully deprotonated AsO 4 3− (pK a3 = 11.2) 23 and deprotonation of nearly all Fe(III) (oxyhydr)oxide surface oxygen atoms. In particular, the pK a values of most singly coordinated surface oxygens of Fe(III) (oxyhydr)oxides are estimated to lie between 12 and 13, 40,41 which yields increasingly negative sorbent surface charge even as NaOH reaches 1 M. Therefore, As(V)-HFO surface complexes are destabilized by NaOH addition via intense charge repulsion between the negatively charged sorbent surface and As(V) at high pH. ...
... Although in some places it should discharge alum sludge in economic and efficient way (Thabet et al. 2021;Tony et al. 2016a, b;Zhao et al. 2013;Turner et al. 2019), in other places such as Egypt it disposed directly to the nearby drains which further reach to water sources, such as lakes and rivers (Tony and Tayeb 2016;Tony 2020a, b). A technical solution for such by-product alum sludge waste is to undergo for dewatering technique to minimize its amounts. ...
Significant co-conditioning of aluminum-based sludge using alternative conditioner (natural biopolymer-magnetite/H2O2) as a Fenton conditioner for improving the sludge dewaterability is investigated in the current study. Firstly, natural biopolymer/magnetite (NBP-M) were prepared in various ratios and the samples labeled as (NBP-M-(1:1); NBP-M-(1:3) and NBP-M-(2:1). Focuses were placed on factors influencing such novel Fenton conditioner. Capillary suction time (CST) was utilized to assess sludge dewaterability. Experiments have exhibited that significant development of alum sludge dewaterability could be attained at minimum reaction time and using low concentrations of the applied catalyst, i.e. natural biopolymer/magnetite and H2O2. It was found that sludge conditioning and dewaterability became better with increasing both reagents concentrations. A Box–Behnken experimental design based on the response surface methodology was investigated to explore the optimum of the influencing variables, i.e. catalyst (NBP-M) concentration, H2O2 loading and pH. The optimized values for NBP-M, H2O2, and pH are 46 and 380 mg/L, respectively at pH 3.0, at which the CST reduction efficiency of 58 ± 3% can be attained, this approved with that predicted by an established polynomial model in the current investigation.
... Landfill fees and taxes are increasing to promote the use of treatment sludge (Bolan et al., 2013). Due to its low combustibility and nutritional value, incineration or digestion is not a reasonable disposal option for WTP sludge (Turner et al., 2019). Therefore, there is an increasing interest in research for WTP sludge utilization options. ...
Coagulants such as aluminum sulfate (Al2(SO4)3 (alum)) and ferric chloride (FeCl3) used in water treatment plants (WTPs) led to the generation of sludge that is usually disposed to landfills. However, the utilization of WTP sludge is being encouraged by authorities to achieve sustainable development. This study aims to investigate WTP sludge utilization in a pilot-scale high-rate activated sludge (HRAS) system as a substitute for conventional coagulants. Based on jar tests, the iron sludge was selected for pilot-scale testing due to its superior ability to enhance the treatment efficiency of the HRAS process compared to alum sludge. Iron sludge addition (20.1 ± 1.6 mg dry sludge/L wastewater) slightly improved the removal efficiency of particulate chemical oxygen demand (pCOD) from 74 % to 81 % (p-value: 0.014). Iron sludge addition had a distinct effect on the sludge characteristics of the HRAS process. The average median particle size (d50) increased from 96 ± 3 to 163 ± 14 μm (p-value<0.00) with the addition of iron sludge, which improved the settleability of the HRAS process sludge. However, the biochemical methane potential (BMP) of the HRAS process sludge decreased by 8.9 % (p-value<0.00) after iron sludge addition. In a scenario analysis of WTP sludge use in a hypothetical HRAS plant, the effluent quality index (EQI), an indicator of environmental impact, was calculated and the cost related to the operation (the transfer and landfill disposal of WTP and HRAS process sludge, energy and chemical consumption of the HRAS plant) was estimated. As a result, using WTP sludge in the HRAS plant did not significantly affect the EQI of the plant but decreased overall cost by 11 %. The results showed that the use of WTP sludge as a coagulant in wastewater treatment could achieve mutual benefits for WTPs and WWTPs and have the potential to realize the circular economy model.
... These include ion exchange, reverse osmosis, membrane filtration, chemical precipitation, and adsorption [15]. These methods have proven to be successful in their functions but have drawbacks that are worthy of note; thus, they have a high cost of operation and residual disposal issues, which in some cases generate new waste that also needs treatment [16]. The high capital-intensive operation cost and residual disposal issues have become discouraging and a source of concern for small start-up industries. ...
Oilfield Produced Water is one of the amplest wastes resulting from oil and gas operations and it’s of great industrial concern due to its quantity, concentration, and cost of treatment; thus, it needs cheaper and more available options. Peat being an option is a renewable brown deposit resembling soil, formed as a result of an accumulation of organic matter, also known to have a rich carbon content. This research work aims to comparatively synthesize peat soil with ZnCl2 and H3PO4, carbonize, characterize, and determine the efficiency of heavy metal adsorption in Oilfield Produced Water. The peat samples were collected from Warri City commonly referred to as Oil City in southern Nigeria and were impregnated with ZnCl2 (PAC-ZC); H3PO4 (PAC-HP); ZnCl2 and H3PO4 at a ratio of 1:1 (PAC-ZC+HP) and with De-ionized water as control (PAC-D). After activation, peat was carbonized at 400oC for 1 hour. Fourier-Transform Infrared Spectroscopy analysis showed all five samples have a strong silicate ion peak between 998.9 - 1028.7cm-1, the presence of Vincy C-H group at 909.5cm-1, broad shaped polar O-H bond between 369.5 – 3623.0cm-1 and an adsorption peak between 2929.7 – 2012.8cm-1 which disappeared after activation and carbonization. Scanning Electron Microscopy micrograph shows a surface enhancement after activation and carbonization. The heavy metals (Pb, Cu, Ni, Zn & Fe) level in the Oilfield Produced Water was analyzed before and after treatment with Peat Activated Carbon using Atomic Absorption Spectrometry. Four dosages (1,2,3, and 4g) of each Peat Activated Carbon were used to treat 100ml of Oilfield Produced Water. PAC-ZC and PAC-ZC+HP showed 100% efficiency in the removal of turbidity, Pb, Cu, Ni, and Fe. However, the overall efficiency trend of the adsorption capacity of the Peat Activated Carbon was PAC-ZC > PAC-ZC+HP > PAC-HP > PAC-D. With the experimental result, PAC-ZC and PAC-ZC+HP can be used as treatment options for Oilfield Produced Water.
... Around four to five hours, the temperature of the basin water with CNP-coated beads was higher than the temperature of the water disinfection (65.0 • C), which promotes the efficient dying of bacteria and other pathogens. Besides, CNP photothermal effect and its antimicrobial and inactivation properties also helped to remove microbial contamination in kitchen wastewater [75,76]. On May 5, 2022, during the solar distillation of KWW with CNP-coated beads, a high basin water temperature of 66 • C was achieved. ...
... At the end of the experiments at 18:00 hrs., the lowest water temperature was observed, 57.7 • C as compared to the 35.0 • C temperature of KWW without CNP-coated glass beads. Similar temperature enhancement was also observed by Ibrahim et al. [76] in conventional pyramid solar still with paraffin wax and graphene oxide. A primary concern associated with wastewater treatment is the disposal of residual water at the end of experiments [77]. ...
... This produces clean water fit for human consumption but also generates large quantities of water treatment residuals (WTRs) as the by-product (estimated to be up to 1-3% v/v of treated water), comprising the aluminium or iron salt derivatives and any removed impurities (Dassanayake et al., 2015). Once dried WTRs are in some ways comparable to soils as they consist of iron and aluminium oxihydroxides, organic matter, and varying amounts of other elements including many that are important plant nutrients such as nitrogen, copper, nickel, and zinc (Turner et al., 2019). Therefore, in an effort to move towards a more circular economy and the sustainability ideal of recycling valuable nutrients, and also to avoid or reduce the escalating costs of disposal via landfill or incineration, WTRs are increasingly being applied to land for general soil improvement and nutrient additions (Turner et al., 2019). ...
... Once dried WTRs are in some ways comparable to soils as they consist of iron and aluminium oxihydroxides, organic matter, and varying amounts of other elements including many that are important plant nutrients such as nitrogen, copper, nickel, and zinc (Turner et al., 2019). Therefore, in an effort to move towards a more circular economy and the sustainability ideal of recycling valuable nutrients, and also to avoid or reduce the escalating costs of disposal via landfill or incineration, WTRs are increasingly being applied to land for general soil improvement and nutrient additions (Turner et al., 2019). It has been determined that the main contributors to the chemical properties of WTRs are the properties and characteristics of the raw water source and the type of coagulant used during treatment (Al or Fe) (Babatunde & Zhao, 2007;Turner et al., 2019). ...
... Therefore, in an effort to move towards a more circular economy and the sustainability ideal of recycling valuable nutrients, and also to avoid or reduce the escalating costs of disposal via landfill or incineration, WTRs are increasingly being applied to land for general soil improvement and nutrient additions (Turner et al., 2019). It has been determined that the main contributors to the chemical properties of WTRs are the properties and characteristics of the raw water source and the type of coagulant used during treatment (Al or Fe) (Babatunde & Zhao, 2007;Turner et al., 2019). There has however been very little research conducted to date on the microbial suites within WTRs or the potential influence that additions of WTRs might have on native soil microbial communities; hence, the microbial community composition of WTRs and any influence it might have on soil microflora are still poorly understood. ...
The clarification of drinking water leads to the production of large quantities of water treatment residuals (WTRs). DNA was extracted from six WTR samples collected from water treatment plants within the UK to compare their bacterial communities and examine whether factors such as coagulant usage (aluminium versus iron salt), the type of water source (reservoir or river), or leachable chemical composition influence these communities. Bacterial 16S variable region 4 (V4) was amplified and sequenced using Illumina MiSeq sequencing. The most abundant phyla in WTR samples were Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria, and Firmicutes, collectively representing 92.77-97.8% of the total bacterial sequences. Statistical analysis of microbial profiles indicated that water source played a significant role in microbial community structure, diversity, and richness, however coagulant type did not. PERMANOVA analysis showed that no single chemical variable (pH, organic matter, or extractable element concentration) influenced microbial composition significantly; however, canonical correspondence analysis of WTR microbiomes yielded a model using all these variables that could be used to explain variations in microbial community structures of WTRs (p < 0.05). No common, potentially toxic cyanobacteria, or related pathogens of concern were found. Analysis with PICRUSt showed that WTRs all had similar predicted microbial functional profiles. Overall, the results indicate that WTRs analysed in this study are unlikely to pose any threat to soil microbial community structure when applied to land as a soil conditioner or enhancer and may help to enhance the soil microbial community.
... Up to now, except for the reuse routes in eutrophic water purification processes, there are other reuse types, including reuse of SF as construction materials (e.g., alum sludge) or even as a partial replacement for clay in clay brick manufacturing as well as in cement production (Razali et al., 2007;Zhao et al., 2016). Furthermore, land-based applications, which comprise the wide range of areas related to agriculture, forestry, and gardening, are also good alternatives for reuse and are worth further investigation and application Turner et al., 2019). ...
The use of natural agro-industrial materials as suspended fillers (SFs) in floating treatment wetlands (FTWs) to enhance nutrient removal performance has recently been gaining significant attention. However, the knowledge concerning the nutrient removal performance enhancement by different SFs (alone and in mixtures) and the major removal pathways is so far inadequate. The current research, for the first time, carried out a critical analysis using five different natural agro-industrial materials (biochar, zeolite, alum sludge, woodchip, flexible solid packing) as SFs in various FTWs of 20 L microcosm tanks, 450 L outdoor mesocosms, and a field-scale urban pond treating real wastewater over 180 d. The findings demonstrated that the incorporation of SFs in FTWs enhanced the removal performance of total nitrogen (TN) by 20–57% and total phosphorus (TP) by 23–63%. SFs further enhanced macrophyte growth and biomass production, leading to considerable increases in nutrient standing stocks. Although all the hybrid FTWs showed acceptable treatment performances, FTWs set up with mixtures of all five SFs significantly enhanced biofilm formation and enriched the abundances of the microbial community related to nitrification and denitrification processes, supporting the detected excellent N retention. N mass balance assessment demonstrated that nitrification-denitrification was the major N removal pathway in reinforced FTWs, and the high removal efficiency of TP was attributable to the incorporation of SFs into the FTWs. Nutrient removal efficiencies ranked in the following order among the various trials: microcosm scale (TN: 99.3% and TP: 98.4%) > mesocosm scale (TN: 84.0% and TP: 95.0%) > field scale (TN: −15.0–73.7% and TP: −31.5–77.1%). These findings demonstrate that hybrid FTWs could be easily scaled up for the removal of pollutants from eutrophic freshwater systems over the medium term in an environmentally-friendly way in regions with similar environmental conditions. Moreover, it demonstrates hybrid FTW as a novel way of disposing of significant quantities of wastes, showing a win-win means with a huge potential for large-scale application.
... A schematic representation of this process is depicted in Figure 1. [20]. ...
Sugarcane bagasse is an abundant and renewable agricultural waste material generated by the sugar industry worldwide. The use of sugarcane bagasse as a bio-coagulant precursor in water treatment is an eco-friendly and cost-effective approach that has shown great potential. This article reviewed the prospects and challenges of utilizing sugarcane bagasse as a bio-coagulant precursor for water treatment. The article reviewed past studies and explored the properties and chemical composition of sugarcane bagasse and the bioactive compounds that can be extracted from it, as well as their potential coagulation performance in water treatment. It was observed that there are few studies that have been published on the subject. The effectiveness of sugarcane bagasse-based coagulants varies depending on several factors, such as pH, temperature, and water quality parameters. However, the lack of standardization in the production of sugarcane bagasse-based coagulants is a challenge that needs to be addressed. Additionally, the optimization of extraction and processing methods to enhance the effectiveness of sugarcane bagasse-based coagulants needs to be investigated further. In conclusion, the use of sugarcane bagasse as a bio-coagulant precursor holds great promise for the future of sustainable water treatment. The potential for sugarcane bagasse to be used as a bio-coagulant precursor highlights the importance of exploring alternative and sustainable materials for water treatment.
... It is estimated that water treatment results in 1-3% of WTRs by volume of the pretreated water [10]. Internationally, a large portion of WTR disposal is via landfill, which results in disposal costs being added to overall water treatment costs [11]. When WTRs are deposited into landfills, the transport distance associated with disposal is of growing concern given the recently defined carbon emission targets internationally, nationally (i.e., Scotland's 2045 net-zero emission target [12]), and at a business level [13]. ...
... This report will focus on alum WTR, as treatment of water with Al salt is the technique generally used in Scotland. The characteristics of WTRs depend on factors such as the initial characteristics of water and the method of treatment [11]. Water acquired from surface or underground water sources contains various types of suspended solids from clay to sand-sized particles. ...
... To produce fully dried WTR pallets, it is suggested room temperature drying for 3 days and then 24 h oven drying at a temperature of 110 • C [18]. The specific gravity of solids ranges between 1.8 and 2.2 [11]. ...
Water Treatment Residuals (WTRs) are a by-product of the addition of chemical coagulants to water during the water treatment process and are a mixture of water and organic and inorganic matter that coagulates during the treatment process. WTRs often contain metals such as iron, aluminium, and manganese that have been oxidised as part of the process or are constituents of the coagulation chemicals used. The metals within WTRs are of interest with regard to applying these sludges to agricultural land. WTRs can also contain beneficial organic matter and nutrients (primarily nitrogen). The nature of the benefits delivered is largely dependent on the quality of the raw water and these beneficial components are generally found in much smaller quantities in WTRs than are found in sewage sludge produced from wastewater. However, WTRs can still be used to enhance the physical properties of soils. As urban populations increase in size, it is anticipated that the tonnage of WTRs will increase significantly in the future. At present, the majority of WTRs are disposed of in landfills; however, landfill charges are increasing significantly, making disposal of an increasing tonnage of WTRs financially unviable. In terms of a circular economy, the procedure of reusing WTRs for alternative applications satisfies the Scottish Government’s goals in terms of waste prevention and reducing the amount of material being sent to landfill as set out in the Proposals for Legislation in 2019. Given the potential benefits in terms of cost savings and compliance with government legislation, and the complexities of understanding where and when WTRs can be used in land applications, we developed a Decision Support Tool (DST) that uses data obtained from an extensive review of approaches in other countries to assist in decision making. We also conducted a pre-application analysis and provided guidance on when and where WTRs can be used in land applications and when they are not suitable, presented in a simplified format that requires few inputs from the user in order to simplify the process and removes the requirement for a specialist operator during pre-application analyses.
... Potential sorbent Different materials have variable reactivity May contain As and radioactive isotopes Zhao et al. 2018;Dayton and Basta 2001;Howells et al. 2018;Lombi et al. 2010;Mahdy et al. 2009, Turner et al. 2019Nguyen et al. 2022 Wood ash Soil physical properties, Soil pH, fertiliser, organic matter ...
Globally, waste disposal options such as landfill, incineration, and discharge to water, are not preferred long-term solutions due to their social, environmental, political, and economic implications. However, there is potential for increasing the sustainability of industrial processes by considering land application of industrial wastes. Applying waste to land can have beneficial outcomes including reducing waste sent to landfill and providing alternative nutrient sources for agriculture and other primary production. However, there are also potential hazards, including environmental contamination. This article reviewed the literature on industrial waste applications to soils and assessed the associated hazards and benefits. The review investigated wastes in relation to soil characteristics, dynamics between soils and waste constituents, and possible impacts on plants, animals, and humans. The current body of literature demonstrates the potential for the application of industrial waste into agricultural soils. The main challenge for applying industrial wastes to land is the presence of contaminants in some wastes and managing these to enhance positive effects and reduce negative outcomes to within acceptable limits. Examination of the literature also revealed several gaps in the research and opportunities for further investigation: specifically, a lack of long-term experiments and mass balance assessments, variable waste composition, and negative public opinion.
