Water Treatment Residuals Research Articles

Chemical functionalization of drinking water treatment residuals with calcium silicate hydrate to treat metal-enriched waters

Drinking water treatment residuals (DWTRs) provide an opportunity to further embrace circular economy in the urban water cycle. DWTRs surface properties can be improved by chemical functionalization to enhance the pollutant removal performance. Fe/Al-DWTRs were functionalized with nanostructured calcium silicate (nanoCSH) to remove Cu(II) and As(V) from rivers, simulating an accidental acid spill. Model raw DWTRs were generated using raw water. DWTRs were physicochemically characterized by a multi-technique approach (SEM-EDS, FT-IR, BET, XRD). Sorption experiments were performed using Cu(II) and As(V) by varying the initial pH and DWTRs doses. Compared with raw DWTRs, NanoCSH_DWTRs demonstrated a higher removal efficiency in acidic settings, faster removal rates, and higher effectiveness at lower dosages. Kinetic and equilibrium sorption experiments were performed. Experiments simulating accidental Cu and As pollution from acid drainage revealed that NanoCSH_DWTRs had a higher collective removal of As(V) when Cu(II) was present, most likely due to the synergistic relationship formed by the tertiary metal-surface complexes. An application approach was implemented using theoretical case studies. NanoCSH_DWTRs reduced the dose required to treat metal(loid)-enriched water compared to raw DWTRs. NanoCSH_DWTRs would provide an alternative as a first line of defense against the accidental release of acidic drainage.

Use of Bacteria to Recover Coagulant from Water Treatment Residue and Reuse for Turbidity Removal from Water

Aluminum is present in significant concentrations in water treatment residue (WTR), a waste product obtained during turbidity removal in drinking water treatment. This study aimed at exploring the potential for recovery of coagulant from WTR using Acidithiobacillus ferroxidans (ATF) and reusing the recovered coagulant (RC) for turbidity removal from water. The activity of ATF was measured by monitoring the pH and Al recovery (in %, AlR%). The effects of two factors (WTR and sulfur dose) on the activity of ATF were studied using central composite design (CCD) and response surface methodology (RSM). The results indicated that the bacteria activity decreased with an increase in WTR dose. The results also revealed that the sulfur dose does not have a significant effect on the ultimate AlR%; however, it significantly reduced the time required for achieving AlR%. ANOVA analysis indicated that the obtained model and factors were significant. The maximum AlR% around 70.9% was obtained with 10 g/L of WTR dose and 8 g/L of sulfur dose. The RC was reused for the turbidity removal from lake water and synthetic turbid water (STW) and compared with the turbidity removal achieved with 1% (w/v) aluminum sulfate. The doses of RC to bring the turbidity <5 NTU in lake water and STW were found to be 0.75 and 1 mL/L respectively. To obtain similar turbidity level, the dose required with aluminum sulfate was 2.5 and 1.5 mL/L for lake water and STW, respectively. There was no significant change in the pH and sulfate and metal concentrations in the effluent treated with RC. The results obtained indicate that the RC is efficient in turbidity removal. The RC, therefore, has potential to reduce the demand for fresh alum for water treatment purposes and provide an alternative use of a waste material.

Potential Benefits and Disbenefits of the Application of Water Treatment Residuals from Drinking Water Treatment Processes to Land in Scotland: Development of a Decision Support Tool

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.

Hydroxylamine facilitated catalytic degradation of methylene blue in a Fenton-like system for heat-treatment modified drinking water treatment residues.

Rational treatment of drinking water treatment residues (WTR) has become an environmental and social issue due to the risk of secondary contamination. WTR has been commonly used to prepare adsorbents because of its clay-like pore structure, but then requires further treatment. In this study, a Fenton-like system of H-WTR/HA/H2O2 was constructed to degrade organic pollutants in water. Specifically, WTR was modified by heat treatment to increase its adsorption active site, and to accelerate Fe(III)/Fe(II) cycling on the catalyst surface by the addition of hydroxylamine (HA). Moreover, the effects of pH, HA and H2O2 dosage on the degradation were discussed with methylene blue (MB) as the target pollutant. The mechanism of the action of HA was analyzed and the reactive oxygen species in the reaction system were determined. Combined with the reusability and stability experiments, the removal efficiency of MB remained 65.36% after 5 cycles. Consequently, this study may provide new insights into the resource utilization of WTR.

Effects of simulated acid rain and carbon-rich water on mercury mobilization in soils amended with aluminum-based drinking water treatment residuals

Mercury (Hg) contamination in soils is of concern because of its known adverse effects on ecosystem functions and human health. Research on how to reduce Hg contamination in soil is still needed, mainly because of the difficulties in remediating Hg-contaminated soils while minimizing adverse effects on treated systems. We investigated the potential of a waste substrate, aluminum (Al)-based drinking water treatment residuals (Al-WTRs), as a low-cost sorbent for immobilizing the mobile fraction of Hg in contaminated soils using column leaching studies. Because of the known role of acidic deposition and dissolved organic matter on the environmental cycling of Hg, columns packed with Hg-contaminated alluvial soils collected from the watershed of Poplar Creek in Tennessee of USA were leached using either the synthetic precipitation leaching procedure (SPLP) to simulate the effects of acid rain or low pH dissolved organic carbon (DOC) rich river water (Suwannee River water, pH 4.20) to mimic soil flooding events with DOC-rich waters. The results show that, for soils with very high mobile Hg fractions, control columns without Al-WTR leached with the SPLP solution retained only 51% of total-Hg, which was significantly less (p ​< ​0.05) than in the Al-WTR treated soil columns (up to 80%). Leaching with DOC-rich river water (53.3 ​mg ​C/L) decreased the sorption capacity of Al-WTR. Using waters with increasing DOC concentrations (from 5.33 to 40 ​mg ​C/L) resulted in the removal of 63% of the initial mass of Hg in the control columns compared to 22–29% in the columns amended with 2 and 5% Al-WTR. Overall, Al-WTR can immobilize Hg under extreme leachability conditions and should be considered as a potential sorbent for in situ remediation of Hg-contaminated soils. However, further studies are needed on the fate of Al-WTR-immobilized Hg.

Application of modified water treatment residuals in water and wastewater treatment: A review

Large quantities of sludge known as water treatment residuals (WTRs) are generated from water treatment facilities across the world. Various attempts have been made to reuse these residuals. Among the different applications of WTRs, their reuse in water and wastewater treatment has received more attention. However, direct application of raw WTRs is associated with some limitations. In the last decade, in order to improve their characteristics, numerous investigators have modified WTRs by different methods. This paper reviews the different methods applied to WTRs to enhance their characteristics. The effects of these modifications on their characteristics are explained. The applications of modified WTRs as a filtration/adsorption medium for treating textile/dye wastewater, groundwater containing different anionic and cationic pollutants, storm water runoff, and as a substrate in constructed wetlands are presented in detail. Future research needs are highlighted. The review clearly indicates the potential of different modification methods to improve the removal of a variety of pollutants by WTRs from water and wastewater.

Green engineered mulch for phosphorus and metal removal from stormwater runoff in bioretention systems

Phosphorus and metals in stormwater runoff are major causes of water quality degradation. Bioretention systems are increasingly implemented to improve stormwater quality and to better manage stormwater quantity. Many studies have focused on modifying the composition of the soil bed to improve pollutant removal. However, the pollutant removal performance of bioretention systems can diminish over time, such as when clogging of the media occurs. Sediment accumulation on the soil surface may inhibit infiltration into the soil bed, thus limiting pollutant removal. Soil replacement may be eventually required as pollutants accumulate in the soil. In this study, a green retrofit material, called green engineered mulch (GEM), was generated by coating regular wood mulch with aluminum-based water treatment residuals (WTR) via a simple and low-energy process (patent pending). The GEM was developed to serve as a green retrofit for bioretention systems to enhance the removal of phosphorus and metals from stormwater runoff. The GEM was placed in a rain garden in Secaucus, NJ, USA for 15 months, during which 12 storm events (ranging from 6.0 mm to 89.6 mm) were monitored. Runoff and infiltrate samples were analyzed for dissolved and total concentrations of phosphorus and metals, along with other key water quality parameters. The GEM significantly reduced (p < 0.05) the total concentrations of phosphorus and metals in stormwater infiltrate compared to the inlet, unlike the regular mulch. Minimal or no contact with the GEM resulted in no significant pollutant removal from surface runoff. No significant pollutant export from the GEM was observed. The spent GEM can be disposed of as non-hazardous waste in municipal landfills. This study demonstrates that the GEM is a safe and effective retrofit. Moreover, the GEM is a simple and economical retrofit solution that can be used in place of regular mulch in bioretention systems.

Removal of gatifloxacin by activated peroxymonosulfate using co-pyrolysis materials of water treatment residuals and biomass: Nonradical-dominated mechanisms enhanced by adsorption

Magnetic porous biochar derived from water treatment residuals and corn stalk (WTR-CS) was prepared by one-step pyrolysis method and applied for peroxymonosulfate (PMS) activation for gatifloxacin (GAT) removal. The results demonstrated that the adsorption and degradation efficiency of the WTR-CS/PMS system increased with the increasing pyrolysis temperature by changing their porosity, iron species and carbon configurations. WTR-CS obtained at 1000 °C (WTR–CS–1000) exhibited the best GAT removal effect, slight Fe leaching, strong stability and reusability. About 42.77% of GAT (40 mg L−1) was removed in the adsorption phase and 95.12% in total (90 min), accompanied by a 77% reduction in total organic carbon (TOC). The kinetic analysis demonstrated that adsorption was a key step in the overall catalytic process. Based on the quenching experiments, ESR and electrochemical tests, free radicals (SO4•-, ·OH and O2•-) and nonradical (1O2 and electron transfer) pathways jointly acted in the reaction, and nonradical pathway was dominant in the reaction. Four degradation pathways were proposed based on the intermediates detected by LC-MS, and the eco-toxicity of degradation intermediates was predicted by ECOSAR program. This study provides a new strategy for simultaneous iron-containing WTRs resource utilization and pollutant removal by synergistic adsorption and oxidative degradation.

Mobility and bioaccessibility of arsenic (As) bound to titanium dioxide (TiO2) water treatment residuals (WTRs)

This work systematically describes arsenic mobility and potential bioaccessibility of arsenic-enriched titanium dioxide water treatment residuals (TiO2 WTRs) by employing a suite of wet chemical experiments and spectroscopic measurements. Specifically, Environmental Protection Agency (EPA) digestion method 3051a indicated <3% of total arsenic in the solid phase was released, and arsenic assessed by EPA method 1340 for bioaccessibility was below detection limits. A novel finding is while the arsenic appeared to be stable under highly acidic digestion conditions, it is in fact highly mobile when exposed to simple phosphate solutions. On average, 55% of arsenic was extracted from all samples during a 50-day replenishment study. This was equivalent to 169 mg kg−1 arsenic released from the solid phase. Macroscopic desorption experiments indicated arsenic likely formed inner-sphere bonds with the TiO2 particles present in the samples. This was confirmed with X-ray absorption spectroscopy (XAS), where an interatomic distance of 3.32 Å and a coordination number (CN) of 1.79 titanium atoms were determined. This translates to a configuration of arsenic on TiO2 surfaces as a bidentate binuclear inner-sphere complex. Thus, both macroscopic and spectroscopic data are in agreement. During incubation experiments, arsenic(V) was actively reduced to arsenic(III); the amount of arsenic(III) in solution varied from 8 to 38% of total dissolved arsenic. Lastly, elevated concentrations and mobility of vanadium in these systems merit further investigation. The high mobility of arsenic and its potential for reduction when reintroduced into the environment, particularly in agriculturally important areas, presents an important risk when waste products are not properly managed.

Coapplication of water treatment residual and compost for increased phosphorus availability in arable sandy soils

AbstractIntroductionSoil degradation coupled with poor access to organic nutrient resources remains a major constraint in increased crop productivity in sub‐Saharan Africa, thus hindering the continent's efforts in achieving the United Nations' Sustainable Development Goals, particularly goals 1 (end poverty), 2 (zero hunger) and 3 (improve human health). Water treatment residual (WTR), a by‐product of clean water treatment, has been identified as an alternative organic nutrient resource for crop production. However, there are some inconsistences in soil phosphorus (P) dynamics following aluminium WTR (Al‐WTR) application.Materials &amp; MethodsA laboratory experiment was conducted to evaluate the P sorption of a sandy soil amended with 10% Al‐WTR, 10% compost (C) as a quasi‐control, 10% C + 10% Al‐WTR (10% coamendment) and 5% C + 5% Al‐WTR (5% coamendment) under varying levels of pH, particle size and P concentration. We calculated crop P fertilizer requirements under different amendments.ResultsThe results demonstrated that all amendments exceeded the minimum of 0.2 mg P L−1 needed in soil solution at equilibrium to maintain plant growth. However, the maximum P sorption capacity was higher for 10% Al‐WTR single amendment, ranging from 770 to 1000 mg P Kg−1, and from 714 to 1000 mg P Kg−1 and 555 to 909 mg P Kg−1 for 10% and 5% coamendments, respectively, across a range of pH and soil particle size fractions. The coamendments showed a reduction in crop P fertilizer requirements by ranges of 30–60% and 60–70% for the 10% and 5% coamendment levels, respectively, across different pH and particle sizes, relative to 10% Al‐WTR.ConclusionResults show that the use of 5% coamendment in sandy soils increases P availability sufficiently to improve crop yields. The results provide scope for using Al‐WTR coamendments to rebuild soil health in sandy soils in urban agriculture and increase macronutrient provision in crops to support human health.

Mitigation of nutrient leaching from bioretention systems using amendments

Bioretention systems have been showcased to be effective in reducing stormwater quantity and improving stormwater quality. However, the systems can also leach nutrients especially during their initial operation, which needs to be mitigated to optimize their benefits. To examine the efficiency of six amendments selected primarily for reducing phosphorus (P) leaching, six amended and two control cells were constructed and monitored soon after their construction in the field of the 2020 growing season. The effects of the amendments on both the hydrological performance (in terms of water retention rate (WRR)) and water quality performance (in terms of the event mean concentration and pollutant removal rate) were investigated. The results showed that all amendments had the capability of preventing or mitigating P leaching from bioretention systems to varying degrees, with the water treatment residual (WTR) outperforming all other amendments, followed by the activated aluminum (AA) and sorptiveMEDIA (SM) amendments. In addition, some of the amendments (i.e., drywall (DRY), WTR, and SM) were also found to be beneficial in reducing the nitrogen (N) leaching to a slight degree, whereas eggshell (EGG) introduced an extra source of N leached. Furthermore, the temporal evolution of the P leaching of the amendment cells was found to be different from that of the control cells. The same result was not observed for the temporal evolution of the N leaching, implying that the amendments (except EGG) did not largely affect the N leaching. Among the amendments’ effect on WRR, there was no obvious difference. Whereas the observed differences between the control cells and some amendment cells in vegetation growth and antecedent media moisture condition might imply their potential impacts on the hydrologic performance. Overall, other than P leaching, the use of amendments affected other functions of bioretention systems, which should be taken into consideration when selecting an amendment for practice.

Systematic Evaluation of Materials to Enhance Soluble Phosphorus Removal Using Biofiltration or Bioswale Stormwater Management Controls

Significant environmental impact can be caused by surface runoff when it transports excessive phosphorus (P) to downstream surface waters. Excessive P can cause uncontrolled aquatic plant growth, low dissolved oxygen, and increased fish mortality. Urban stormwater is composed of both dissolved and particulate P fractions in roughly equal proportions. Many stormwater management controls (SMCs) like biofiltration and bioswales can remove particulate P easily through sedimentation and filtration processes, but dissolved P is much harder to remove. These SMCs also contain compost, which is excellent for removing many other pollutants but can decompose and release P. This laboratory study systematically evaluated dissolved P removal efficiency of 40 different adsorptive materials through jar tests and adsorption isotherm kinetics, column tests that emulate biofiltration systems, and channel tests to emulate bioinfiltration swales. The jar tests yielded 12 materials for further testing using complete adsorption isotherms. Seven of these 12 materials were tested extensively in the column studies. The best materials for enhancing P removal in the columns were activated alumina, alum-based water treatment residuals (WTRs), layered double hydroxyl (LDH), and zero-valent iron (ZVI) aggregate, all exceeding 90% P removal. Based on performance, three were chosen for the channel study: activated alumina, alum-based WTR, and ZVI aggregate. Results showed that lower compost content could reduce P leaching but not eliminate it completely, while biochar mixes were highly variable. Replacing half of the compost with an adsorptive material in a conventional bioretention/bioswale system gave good P removal results. The alum-based WTR is recommended in this study because it ranked excellently for all tests performed, and as a waste material, it can be recycled at a low cost.

Effect of Adding De-Oiled Kitchen Water on the Bioconversion of Kitchen Waste Treatment Residue by Black Soldier Fly Larvae.

With the continuous development of society, the output of kitchen waste (KW) is fast increasing. De-oiled kitchen water (DKW) and kitchen waste treatment residue (KWTR), two main by-products of the KW treatment industry, are produced accordingly on a large scale. The need to develop an effective technique for the utilization of DKW and KWTR is attracting wide attention. In the present study, black soldier fly larvae (BSFL) were employed as a biological treatment method to treat KWTR with the addition of DKW. The influence of DKW (0-140 mL) on the efficiency of BSFL treatment evaluated by the growth and development of BSFL, the body composition of BSFL, the nutrient content of bioconversion residue (BR), and the bioconversion efficiency of KWTR, was investigated. The results showed that the growth and development of BSFL, the body composition of BSFL, and the conversion rate of KWTR were initially promoted and then inhibited with the addition of DKW. Notably, the amount of DKW added in the T110 group was the most suitable for the growth of BSFL and the accumulation of body composition. Compared with the blank comparison group, the content of crude protein (CP), crude ash (CA), salinity, total phosphorus (TP), and dry matter (DM) of BSFL in the T110 group increased by 3.54%, 6.85%, 0.98%, 0.07% and 2.98%, respectively. However, the addition of DKW could steadily increase the nutrient content of BR, with the highest amount at 140 mL DKW. Following DKW addition, the contents of CP, ether extract (EE), crude fiber (CF), organic matter (OM), total nitrogen (TN), TP, and total potassium (TK) were increased by 4.56%, 3.63%, 10.53%, 5.14%, 0.73%, 0.75%, and 0.52%, respectively, compared with those of the blank comparison group. The study showed that DKW could be used as a nutrient additive in the bioconversion process of KWTR by BSFL, which provided a new method for the resource utilization of DKW.

A model for predicting reduction in mobile phosphorus of lake sediment by aluminum drinking water treatment residuals

Drinking water treatment residual (DWTR) derived from flocculation and sedimentation of raw water using aluminum coagulants is a valuable environmental remediation byproduct capable of inactivating phosphorus (P). However, no generalizable model exists in the literature to describe reduction of releasable (mobile) P in lake sediment as a result of DWTR addition. The reduction of mobile P (sum of labile P and reductant soluble P) was investigated in over 100 sub-samples using five sediment samples from two lakes and three DWTRs from different water treatment plants. A consistent relationship was determined across a range of mobile P contents (0.23 g/m2/cm to 0.92 g/m2/cm, or 15.8 to 186.1 µg/g DW) and DWTRs. The relationship was best described as a function of the mobile P content of the sediment and the oxalate-extractable aluminum content of the DWTR. An empirical model was developed to predict the immediate reduction in mobile P following the addition of DWTR containing aluminum. This model was validated using two additional lake sediments and one additional DWTR (R² = 0.995). Thus, the immediate inactivation of P in lake sediment following DWTR addition can be predicted with this model, which can be used with internal P loading or other water quality goals to determine an appropriate DWTR dose. Further recommendations were made about dosing DWTRs for lake restoration, allowing practitioners to use DWTR to inactivate P in lake sediment without conducting individual sorption experiments.

PFAS release from wastewater residuals as a function of composition and production practices

Per- and polyfluoroalkyl substances (PFAS) are a class of highly persistent contaminants that have been linked to human health effects at low exposure concentrations. Public concerns exist that land-application of biosolids may result in the release of PFAS into terrestrial and aquatic ecosystems. The relative importance of inorganic constituents such as Fe and Al, which are known to impact PFAS retention/release behavior in soils, on PFAS release from wastewater residuals (WWRs, i.e., biosolids and sewage sludges) is not well understood. Here, we examine native concentrations and WWR-water partition coefficients of a range of PFAS in the context of WWRs characteristics including oxalate-extractable Fe and Al, organic matter (OM), dissolved organic carbon, and total protein content. Total PFAS concentrations, which included perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, fluorotelomer sulfonates and some sulfonamides, ranged from ∼480 to 3500 μg PFAS kg−1 dry weight. PFAS WWR-water partition coefficients ranged from ∼10 to 20,000 L kg−1, consistent with the literature. PFAS partitioning was significantly correlated to oxalate extractable Al and Fe as well as bulk OM and protein content. These results have important implications for wastewater treatment facilities that recycle Al- and Fe-based drinking water treatment residuals in terms of both PFAS retention and loading.

Composite Barrier Systems for Climate Adaptation

Composite barrier systems, which are two-layer systems of materials (fine-grained material overlying coarse-grained material) of contrasting hydraulic properties, can be used to mitigate the effects of climate change in urban areas, including flooding and shrink swell deformation. Here, a series of experiments were carried out to test a range of materials, including 20-30 mm gravel, recycled crushed concrete, topsoil, and topsoil amended with water treatment residual (WTR). The consideration of waste products here aims to improve the sustainability of composite barrier systems for climate adaptation. The results indicate that WTR-amended topsoil is suitable for use as a fine-grained material in composite barrier systems owing to its enhanced water retention properties. However, while crushed concrete can be used in the coarse-grained layer to form a capillary barrier when the system is dry, once breakthrough has occurred, transmission of water through the barrier is quicker than in composite barriers with 20-30 mm gravel. As such, 20-30 mm gravel is recommended for use in the coarse-grained layer. Two large-scale, outdoor lysimeters were set-up using the recommendations derived from the column experiments. The lysimeter experiments were subjected to a series of simulated rainfall events to enable initial interpretations of composite barrier performance.

The diversity of aluminum-based drinking water treatment residuals for use in environmental remediation

Drinking water treatment residuals (DWTRs) are complex mixtures of organic and inorganic phases generally disposed of as waste materials.

Efficient Adsorption of Tl(I) from Aqueous Solutions Using Al and Fe-Based Water Treatment Residuals

Iron and aluminum water treatment residuals from a water supply plant were used as adsorbents for Tl(I) to treat thallium-containing Tl(I) wastewater and realize the resource utilization of water treatment residuals. The feasibility study results showed that Fe-WTR and Al-WTR reached adsorption equilibria within 120 min. The Langmuir model showed maximum adsorption capacities of Tl(I) on Fe-WTR and Al-WTR as 3.751 and 0.690 mg g−1 separately at an initial concentration of 5 mg L−1. The adsorption capacities of Fe-WTR and Al-WTR positively correlated with pH. The removal of Tl(I) using Fe-WTR exceeded Al-WTR; the adsorbed Tl(I) in Fe-WTR occurred primarily in the reduced state, while the Tl(I) adsorbed in Al-WTR was mainly in acid-extractable and reduced states. FTIR and XPS data showed that Tl(I) and Fe/Al-OH-functional groups formed stable surface complexes (Fe/Al-O-Tl) during adsorption, and there was no redox reaction. This confirmed that WTR is a highly efficient adsorbent for the stable removal of Tl(I), which provides a practical foundation for industrial application in Tl(I)-containing wastewater treatment.

Properties of Recycled Nanomaterials and Their Effect on Biological Activity and Yield of Canola in Degraded Soils

Recycling waste, such as rice straw and water treatment residuals, is important to reduce harmful effects on the environment and to improve canola yield and soil quality in degraded soils. Nanotechnology for the production of nanomaterials from biochar and water treatment residues will be a future revolution for improving soil quality and increasing canola yield in degraded soil. Therefore, this study aims to identify the properties of some recycled nanomaterials, such as nanobiochar (nB) and nanowater treatment residue (nWTR), and their effect on the biological activity and productivity of canola in degraded soils. The results showed that the nWTR and nB contain many functional groups and minerals, and they also have high negative zeta potential. The addition of the studied soil amendments significantly improved microbial biomass carbon (MBC) and biological activity, which played a major role in increasing canola yield. The highest dehydrogenase (DHA) and catalase (CLA) activity was found in nWTR-treated soil at 50 mg kg−1, with increases of 32.8% and 566.7% compared to the control, respectively. The addition of nB greatly improved the growth of canola plants in the soil. This was evident from the increase in the weight of seeds, the weight of 1000 grains, the number of pods per plant, and the highest increase was for nB added at the rate of 250 mg per kg−1 soil. The addition of 50 mg kg−1 of nWTR gave the best results in seed yield by 150.64% compared to the control. These results indicate that recycled nWTR and nB are some of the best waste recycling treatments, in addition to good soil health, in increasing soil biology and canola yield in degraded soils. In the future, research on recycled nanomaterials should examine the residual effect they have on yield, soil quality, and soil fauna in the long term.

Ecofriendly nanoparticles derived from water industry byproducts for effective removal of Cu (II) from wastewater: Adsorption isotherms and kinetics

• Water treatment residuals nanosorbent (nWTR) were characterized and used for copper removal. • The efficient of nWTR was 3.7 times higher than bulk WTR in adsorption copper ions. • nWTR maintained its high adsorption potential (98.7 %)at pH 6. • The adsorption process of copper from wastewater can be repeated for.4 times using the same sorbent(nWTR). Water Treatment Residual nanoparticles (nWTR) has been identified as an adsorbent for the efficient elimination of copper (II) from wastewater. Adsorption parameters pH, dosage, contact time, initial concentration, and temperature were assessed to detect the optimum adsorption conditions for purification contaminated wastewater. The equilibrium between liquid and solid phase occurred rapidly after (120 min) . nWTR was found to have high adsorption capacity for Cu (II). From Langmuir isotherm, the adsorption capacity for Cu (II) was 71.9 mg g −1 , which is about 3.7 times higher than that of bulk particles of WTR. The kinetics data for Cu (II) adsorption followed the pseudo-first-order kinetics. The thermodynamic parameters investigated the spontaneous and endothermic nature of the Cu (II) adsorption activity. High removal percentage (91%) was obtained after five cycles of reusing nWTR indicating the capability of using the sorbent more than four times.