Drinking Water Treatment Sludge Research Articles

Enhancing oxidative desulfurization using sludge-derived ferrate (VI) for dibenzothiophene: an optimization study

Sulfur emissions pose a substantial threat to human health and the environment. To address this, stringent regulations limit sulfur content in fuels, and innovative desulfurization technologies are under active investigation. Oxidative desulfurization (ODS) employs oxidants to convert sulfur compounds into more readily recoverable sulfones. This study explores high-shear mixing in ODS, known as mixing-assisted oxidative desulfurization (MAOD), focusing on dibenzothiophene (DBT) oxidation in model fuels and pyrolysis oil. Fe(VI) derived from drinking water treatment sludge via wet oxidation is utilized in the MAOD process. The research evaluates the impact of ferrate concentration (400 to 600 ppm), phase transfer agent (PTA) concentration (100 to 300 mg per 50 mL of fuel), agitation speed (4,400 to 10,800 rpm), and temperature (40 to 60 °C) on % DBT conversion. Experimental sulfur conversions range from 63.4% to 99.6%. Through response surface methodology, optimal parameters of 537 ppm Fe(VI), 114 mg PTA per 50 mL of model fuel, 8,157 rpm agitation speed, and 41.7 °C are determined. These parameters are applied to pyrolysis oil, achieving a desulfurization efficiency of 53.2%. Notably, increasing Fe(VI) concentration, agitation speed, and temperature significantly enhances sulfur reduction. The study underscores the potential of using potassium ferrate derived from drinking water treatment sludge in MAOD for effective desulfurization and provides insights into the impact of operating conditions on desulfurization efficiency. Ultimately, the research contributes to advancing environmentally friendly and cost-effective desulfurization technologies.

Sludge-Based Superparamagnetic Nano-Sorbent Functionalized by Lanthanum Silicate Nanorods for Phosphorus Adsorption and Fertilization

Phosphorus (P) recovery from wastewater is considered to be a positive human intervention towards sustainable P use in the global P cycle. This study investigated the feasibility of synthesizing a superparamagnetic nano-sorbent that was functionalized by lanthanum silicate nanorods (NRLa-Si) using drinking water treatment sludge (DWTS), evaluating both its P adsorption capacity and fertilization effect. The DWTS-based La-modified P nano-sorbent (P-sorbent D) exhibited complicated but single-layer-dominant adsorption for phosphate, with a maximum adsorption capacity up to 26.8 mg/g, which was superior to that of most of the similar sludge-based P-sorbent. The NRLa-Si-modified P-sorbent D was identified with several characterization techniques and the leaching metal elements from the nano-sorbent were tested, which were below the limits proposed by the Food and Agriculture Organization of the United Nations. In addition, the growth and vigorousness of Arabidopsis thaliana indicated that the exhausted P-sorbent D could be used as a potential water-soluble moderate-release P fertilizer, which was also confirmed by the well-fitted P uptake model and the P desorption pattern from the sorbent–fertilizer. The doped lanthanum silicate nanorods could play the dual role of P complexation enhancement and health/growth promotion. In light of this, this study proposed a new way of reclaiming DWTS as a P-sorbent for fertilization, offering new insights into the path toward “closing the P loop”.

Advancing circular economy: A study of drinking water sludge for potential uses

The high demand for drinking water has increased the by-products from treatment plants, notably during coagulation-flocculation, leading to substantial sludges' accumulation. This study aims to focus on the characterization of drinking water treatment sludge (DWTS) batches from the three last years and statically studying it's uniformity, as exploring potential repurposing options. The samples were characterized using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Loss On Ignition (LOI), and Granulometric analysis. The results evinced that DWTS have a sandy nature, the organic fraction takes third of the DWTS’ chemical composition, the amount of Al2O3 + SiO2 + Fe2O3 is slightly different, with 55.84, 57.47, and 56.14 % for DWTS21, DWTS22, and DWTS23 respectively, as per ANOVA results, which exhibited the consistency sludge composition among the samples, providing valuable insights into repurposing DWTS, and contributing to sustainable and eco-friendly practices in the construction industry especially DWTS21, which presents higher content of CaO with 2.95 %.

Adsorption of Eriochrome Black T on Pseudo Boehmite and Gamma Alumina Synthesized from Drinking Water Treatment Sludge: A Waste-to-Recycling Approach

Eriochrome black T is considered as one of the anionic dyes with potential harmful effects on human health and the environment. Among other processes, adsorption can contribute to the removal of these dyes. In the present study, two adsorbent materials, pseudo-boehmite (γ-AlOOH) and gamma alumina (γ-Al2O3), were synthesized and tested in the removal of the Eriochrome black T molecule (EBT). γ-AlOOH and γ-Al2O3 were obtained by precipitation from NaAlO2 solution at pH = 7, at a temperature of 80 °C, and by the thermal transformation of γ-AlOOH at 800 °C, respectively. In order to gain insights into the structural, chemical, thermal and morphological properties of these materials, numerous analytical techniques were involved, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), differential thermogravimetric–thermal analysis (TGA-DTA), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and specific surface area measurement using the Brunauer–Emmett–Teller (BET) method. Several adsorption parameters were studied, such as the adsorbent dose, initial concentration, pH, contact time and reaction temperature. The kinetic study showed that EBT adsorption follows the pseudo-second-order model. The Langmuir isotherm model revealed a maximum EBT adsorption capacity of 344.44 mg g−1 and 421.94 mg g−1 for γ-AlOOH and γ-Al2O3, respectively. A textural and structural analysis after adsorption highlighted the effective adsorption of the dye.

Efficiency of dry drinking water treatment sludge as adsorbent for methylene blue and acid red 97 removal from aqueous solutions

In this study, drinking water treatment sludge (DWTS) was applied after drying as adsorbent for the removal of methylene blue (MB) and acid red 97 (AR97) from aqueous solutions. DWTS powder was characterized by X-ray fluorescence, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. The thermal behavior of DWTS was examined and leaching tests were carried out to study its chemical stability. DWTS is mainly composed of aluminum (24.65%) and silicium (6.157%) and it has a mesoporous structure with a surface area of 92 m2.g−1. Batch adsorption experiments of MB and AR97 were achieved taking into account the effect of pH, initial dye concentration, adsorbent mass, contact time and temperature. The pseudo-second-order kinetic model provided the best correlation for both dyes, and the intra-particle diffusion is not the only rate-limiting step during the adsorption. Furthermore, the adsorption of MB and AR97 followed the Langmuir isotherm model with a maximum adsorption capacity equal to 46.30 mg.g−1 and 135.13 mg.g−1, respectively. Thermodynamically, the negative values of ΔG° for both the dyes assumes that the adsorption is favored and spontaneous and that the reaction is endothermic (ΔH°>0) and exothermic (ΔH°<0) for MB and AR97, respectively. The entropy ΔS° is positive and proves that there is randomness at the liquid/solid interface during the adsorption process. The results also exhibited that the adsorption of both dyes is a physical process. Finally, DWTS can be considered an effective and low-cost adsorbent due to its simple physical conditioning requiring only dewatering and grinding.

Fe recovery from drinking water treatment sludge for reuse in tannery wastewater treatment: Machine learning and statistical modelling

This work experimentally and numerically studied the reusability of Fe recovered from water treatment sludge as a coagulant and compared its performance with a commercial coagulant in tannery wastewater treatment. The performance of the recycled and commercial coagulants in total suspended solid (TSS), chemical oxygen demand (COD), color, chromium (Cr3+) and turbidity removal was compared with considering pH, coagulant type and dose as independent variables. Additionally, the process was modelled by two statistical and machine learning procedures, i.e., response surface methodology (RSM) and artificial neural network (ANN). For RSM model, a 32 run experimental matrix was designed by factorial design, while ANN model was developed by a dataset extracted from the publications inclusive of the 32 experiments. The results showed Fe recovery rate of 181 mg/g dry sludge. The maximum TSS, COD, color, Cr3+ and turbidity removal by recovered and commercial coagulants were (85 %, 40 %, 42 %, 68 %, and 88 %) and (70 %, 35 %, 49 %, 64 % and 88 %) respectively. ANN COD removal model showed a good prediction in all training, validation and testing phases with R 0.891, 0.963 and 0.917 respectively. While the R for TSS, COD, color, Cr3+ and turbidity statistical models were 0.962, 0.866, 0.960, 0.962 and 0.973 respectively.

A two-step approach of ozonation pre-oxidation and re-flocculation to regulate drinking water treatment sludge: Sludge reflux and enhanced coagulation

The characteristics of drinking water treatment sludge (DWTS) are important factors limiting the coagulation effect after sludge recycling. To enhance the coagulation performance of DWTS recycling, a two-step pretreatment strategy was employed, including ozonation pre-oxidation and the re-flocculation of polymeric aluminum chloride (PACl) and polyacrylamide (PAM). Ozonation pre-oxidation transformed insoluble organic matter into dissolved organic matter (DOM), reducing the organic content by 12.58% for UV254 and 8.94% for dissolved organic carbon (DOC) in the DWTS recycling process. Following re-flocculation with PACl and PAM, the size, zeta potential, and settling velocity of the ozonated sludge were further increased from 30.27 μm, −12.57 mV, and 2.06 mm/s to 187.6 μm, −3.49 mV, and 6.42 mm/s, respectively, which exhibited higher turbidity removal in DWTS recycling process. Following the two-step method, larger, denser, and more reversible flocs were observed during the recycling process, and the settling efficiency of the flocs was enhanced, which enabled achieving better water quality in a shorter duration. These findings provide innovative insights into drinking water plant optimization and sludge management.

Life cycle assessment and thermophysical properties of a fly ash-based geopolymer containing drinking water treatment sludge.

Fly ash-based geopolymers have emerged as a sustainable alternative in construction, leveraging industrial by-products to mitigate CO2 emissions. This study investigates the novel incorporation of drinking water treatment sludge (DWTS) into fly ash-based geopolymers at varying proportions (5-40%). Authors focus is to analyze the thermophysical properties and environmental implications, including a robust life cycle assessment case study conducted within the Moroccan context. The comprehensive analysis encompassed X-ray powder diffraction, apparent porosity, water absorption, scanning electron microscopy, hot disc, compressive strength, and a comparative assessment of fly ash-based geopolymer containing 20% of DWTS (GP-DWTS-20) and ordinary Portland cement (OPC). Notably, the results reveal that DWTS enhances thermal performance, with a remarkable 33% reduction in thermal conductivity observed in geopolymers containing 20% DWTS. This enhancement motivates the potential for innovative fly ash-based geopolymers. Moreover, the study contributes quantifiable evidence of a substantial 48% reduction in global warming potential for DWTS-based geopolymers compared to OPC. These findings underscore the environmental benefits of this alternative while emphasizing avenues for optimization in alkaline solution, curing, and renewable energy integration.

The ability of drinking water treatment sludge to degrade methylene blue in water through combined adsorption/photo Fenton-like process

In the present study, drinking water treatment sludge (DWTS) was reused as a catalyst in advanced oxidation processes for the removal of methylene blue (MB) from aqueous solutions. After determining their chemical and mineralogical compositions by X-ray Powder Diffraction (XRD), BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), Inductively Coupled Plasma (ICP), and FT-IR spectra. DWTS has been used as a heterogeneous photo Fenton-Like catalyst for the oxidation of MB under different parameters, including pH (3-6), H2O2 concentration (9.79-29.37 mM), and dose (1-2.5 g/L). The results showed that within 180 min and under UV light irradiation, more than 86% of MB having a concentration of 50 mg/L were removed using a catalyst loading of 1.5 g/L, a H2O2 dosage of 23.17 mM and a solution pH of 5. The DWTS has a satisfactory stability as the catalyst is stable and have very less iron leaching property.

Effective Removal of Fe(III) Ions from Water Sample Using Activated Drinking Water Treatment Sludge: Isotherms and Kinetic Studies

Effective Removal of Fe(III) Ions from Water Sample Using Activated Drinking Water Treatment Sludge: Isotherms and Kinetic Studies

Fate of micropollutants in a lab-scale urban wastewater system: Impact of iron-rich drinking water treatment sludge

Iron rich drinking water treatment sludge (Fe-DWTS) could be a potential alternative for Fe salts in controlling sulfide in the sewer network. This study investigated the impact of in-sewer dosed Fe-DWTS on the fate of 26 different intrinsic organic micropollutants in wastewater by using a lab-scale integrated system consisting of sewer reactors and a sequential batch reactor (SBR) to simulate urban wastewater collection and treatment. The batch results revealed that seven among these 26 compounds had higher removal in the Fe-DWTS dosed sewer reactor compared to the control sewer reactor. In contrast, the removal of 7 out of the 26 investigated compounds were reduced, along with the biofilm methanogenic activity due to the long-term Fe-DWTS dosing. Cycle experiments in the SBR showed that the removal of acesulfame was enhanced and the formation of carbamazepine, desvenlafaxine, tramadol and hydrochlorothiazide were reduced, compared to their behaviour in the control SBR. However, the long-term experiments showed no adverse or beneficial effect of in-sewer dosed Fe-DWTS on the removal of most micropollutants in the SBR. Codeine, trimethoprim and gabapentin were exceptions with slightly higher concentrations in the experimental SBR effluent, possibly due to change in microbial composition.

Characteristics of organic matter released from drinking water treatment sludge under different storage conditions: Evaluation based on activated carbon adsorbability

Recycling water from drinking water treatment sludge (DWTS) as raw water raises several problems in the drinking water supply. In this study, the impact of storage temperatures and oxygen conditions for DWTS on the characteristics of dissolved organic matter (DOM) released from sludge was evaluated in terms of adsorbability by activated carbon. Results showed that the adsorbability of the released DOM varied greatly with storage temperatures and oxygen conditions. The modified Freundlich isotherm model revealed that the average adsorption strength (KF) estimated based on dissolved organic carbon (DOC) and ultraviolet absorbance at 260 nm (UV260) varied in the ranges of 4.01–12.1 (mg g−1)1-1/n and 23.1–52.6 (L m−1 g−1)1-1/n, respectively. DOM released under the condition without aeration possessed higher adsorbability compared to DOM released under the condition with aeration (1.41–3.01 times for DOC-based; 1.14–2.28 times for UV260-based). Moreover, the KF values of fluorescence excitation-emission matrix (EEM)-based fulvic acid-like and humic acid-like substances were higher than those of tyrosine-like and tryptophan-like substances, indicating humic-like substances released from DWTS were more adsorbable than protein-like ones. The methods or adsorption conditions that can enhance the removal of protein-like substances are essential for dealing with water quality problems associated with recycling water from drinking water treatment sludge.

Comparative study of sediment phosphorus immobilization via the addition of lanthanum-modified and thermal-modified drinking water treatment sludge.

Lanthanum-modified drinking water treatment sludge (DTSLa) and thermal-modified drinking water treatment sludge (TDTS) were prepared from drinking water treatment sludge(DTS). The adsorption properties of DTSLa and TDTS on phosphate in water and the effects on the controlled release and morphology of phosphorus in sediment at different dosages (0%, 2.5%, 5%) were discussed. Combining with SEM, BET, XRD, FTIR, and XPS characterization methods, the immobilization mechanism of DTSLa and TDTS on phosphorus in sediment was explored. The addition of TDTS can transform NH4Cl-P (loosely sorbed P), BD-P (bicarbonate-dithionite extractable P), and Org-P (organic P) into stable NaOH-rP (metal oxide-bound P) in sediment, and the conversion amount will increase with the increase of TDTS supplemental amount. DTSLa converted NH4Cl-P, BD-P, Org-P, and NaOH-rP to more stable HCl-P (calcium-bound P). At the same time, the content of WSP (water-soluble phosphorus) and olsen-P (NaHCO3 extractable P) in sediment can be reduced by the addition of DTSLa and TDTS, reducing the risk of the release of phosphorus from the sediment to the overlying water. In addition, phosphorus can be directly removed from the interstitial water by DTSLa and TDTS, so as to reduce the phosphorus concentration gradient between the overlying water and the interstitial water, thus inhibiting the release of phosphorus from interstitial water to overlying water. The results showed that DTSLa is better than TDTS in terms of its adsorption capacity and adsorption effect on endogenous phosphorus in water, so DTSLa is more suitable to be used as a sediment conditioner to control the phosphorus content in water and sediment.

Utilization of manganese-rich sludge in concrete: Mechanical, nanoscale characteristics and leaching behavior

The management and recycling of heavy metal-rich sludge have posed serious environmental challenges. High levels of potassium permanganate are often used to treat eutrophic water bodies, which produce manganese-rich drinking water treatment sludge (DWTS). Although there have been some studies on recycling sludge in cement-based materials, little attention has been paid to the multiscale behavior of concrete with manganese-rich sludge. In this study, eco-friendly concrete was produced by substituting part of the cement with calcined DWTS (CWTS), and its mechanical properties, drying shrinkage, microstructure, and environmental characteristics were systematically investigated. The results showed that the incorporation of an appropriate amount of CWTS improved the mechanical properties and volume stability of the concrete, and the best performance was achieved when the substitution level was 10%. The 90-d compressive strength of 10% CWTS-modified concrete was relatively increased by 7.91%, while the 150-d drying shrinkage was relatively reduced by 14.84% compared with plain concrete. The pozzolanic action of CWTS consumed part of Ca(OH)2 and increased the degree of reactivity of the paste at appropriate substitution levels. From the perspective of nanoscale characteristics, the incorporation of 10% CWTS reduced the content of the pore phase and clinker and increased the content of the C-S-H phase relative to plain concrete, where high-density C-S-H and low-density C-S-H increased by 12.5% and 6.8%, respectively. Moreover, incorporating an appropriate amount of CWTS also reduced the width of the interfacial transition zone (ITZ), but with the further increase of its content, the width of the ITZ increased. In addition, CWTS-modified concrete not only exhibited safe heavy metal leaching behavior but also had lower costs and carbon emissions. This study provides new insights into the management and recycling of DWTS, especially manganese-rich sludge obtained from the treatment of algal blooms.

Rheological Behavior and Characterization of Drinking Water Treatment Sludge from Morocco

Drinking water treatment generates a high amount of pasty by-product known as drinking water treatment sludge (DWTS). The chemical composition, microstructure and rheological behavior of DWTS are of utmost importance in the calculation, design, optimization, commissioning and control of its treatment processes. The purpose of this research was to characterize the DWTS from the drinking water treatment plant of Marrakech (Morocco), aiming to help future researchers and engineers in predicting its hydrodynamic behavior. The first part of this study was devoted to the physical structure and the chemical composition of sludge. The second part was oriented towards the study of the mechanical properties; a penetration test and a rotational rheology test were performed. For the first test, a force–length penetration diagram was plotted in order to calculate the hardness, the cohesiveness and the adhesiveness of DWTS. For the second test, the shear stress and the apparent viscosity were plotted and fitted to five rheological models, as function of the shear rate, aiming to describe the rheological behavior of samples. The obtained results reveal that the drinking water treatment sludge from Marrakech is a porous, amorphous and highly adhesive material, with a shear-thinning (pseudoplastic) rheological behavior that can be described according to the Herschel–Bulkley model (better in low-rate stresses, R² = 0.98) or the Windhad model (better in high shear rates, R² = 0.96) and is mainly composed of silica, aluminum and iron oxides.

Thermally activated drinking water treatment sludge as a supplementary cementitious material: Properties, pozzolanic activity and hydration characteristics

Drinking water treatment sludge (DWTS), a hazardous municipal solid waste, is Al-rich and Si-rich. Although it can be used as a supplementary cementitious material (SCM), the appropriate treatment temperature of DWTS, the mineral phase transformation in the heating process and hydration characteristics are indefinite. This study explores the physicochemical characteristics and pozzolanic activity of DWTS after thermal treatment at seven different temperatures (105 °C, 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, 1200 °C) and its effects on cement hydration. The results show that DWTS calcined at 800 °C has the highest reactivity due to the presence of γ-aluminum (AlⅣ), which not only exhibits pozzolanic activity but also can undergo hydration reaction with cement to form calcium aluminosilicate hydrate (C-ASH). At lower temperatures (105 °C to 200 °C), DWTS exhibits non-pozzolanic activity due to the presence of a higher content of organic matter (i.e., TOC greater than 5 %). Although the Frattini test proves that the the DWTS treated at medium temperature (400 °C to 600 °C) has pozzolanic activity, it mainly achieves dehydroxylation (similar to the transition from kaolinite to metakaolin) in this temperature range. The reactivity is improved, but the crystal structure does not fundamentally change and the hydration product is calcium silicate hydrate (CSH). After DWTS is calcined at ultra-high temperature (greater than1000 °C), γ-aluminum (AlⅣ) is converted into α-aluminum (AlⅥ) and combines with amorphous quartz to form mullite, which acts as a filler in DWTS-cement samples.

A new approach of aluminum extraction from drinking water treatment sludge using ammonium sulfate roasting process

The drinking water treatment based on the coagulation-flocculation process using aluminum sulfate is widely used the whole word. As the effect of this activity, the huge quantities of the drinking water treatment sludge continue to be an environmental issue and needs to be valorized. The purpose of the present work is to investigate the valorization pathway of this sludge by extracting aluminum using ammonium sulfate roasting and hot water leaching at 80 °C as an alternative method to acid leaching which is energetic and cause corrosion problems. Several techniques were used, i.e., Thermogravimetric/Differential thermal (TGA/DTA) analysis, X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), and inductively coupled plasma - optical emission spectrometry (ICP-OES) to approach the reaction mechanism between sludge and ammonium sulfate. This chemical additive promoted the conversion of aluminum and calcium from the primary phases of the sludge, such as calcite (CaCO3), nacrite (Al2Si2O5(OH)4), and muscovite (KAl2(AlSi3)O10(OH)2)to form soluble metal sulfates in a temperature range of 400 °C to 600 °C. The parameters affecting the extraction, such as roasting temperature, mass ratio of ammonium sulfate to sludge, and roasting time were studied. A recovery of 74 % was obtained for aluminum under the optimum roasting conditions. The experimental results showed also a good chemical affinity between ammonium sulfate and other elements present in the sludge, such as calcium, magnesium, and manganese. The extraction efficiency of these elements was 88 %, 91 %, and 77 %, respectively. The characterization of the leaching residue showed the presence of silicon at high content (35.8 %) and low contents of calcium (0.64 %), magnesium (0.16 %), aluminum (2.75 %), and manganese (0.05 %), which confirm the efficiency of the developed process.

Study on the feasibility and stability of drinking water treatment sludge (DWTS)@zeolite to remove phosphorus from constructed wetlands

The substrate in the constructed wetlands (CW) plays an important role in wastewater treatment. The resource utilization of drinking water treatment sludge (DWTS) has good application prospects, but its powder form is not an ideal substrate and may cause blockage. This paper studies granulated DWTS by loading powdered DWTS on zeolite (DWTS@ZEOLITE). Results show that there should be 1 g of thickener, 5 mL of binder, and 0.15 g of DWTS for the best removal effect. The adsorption process of DWTS@ZEOLITE on phosphorus conforms to the Langmuir model, and the theoretical saturated adsorption capacity is 21.8 mg/g. pseudo-second-order kinetics can be used to fit the adsorption behavior and the adsorption of phosphorus with the DWTS@ZEOLITE was a spontaneous exothermic process. Acidic conditions and humic acid can increase the amount of adsorbed phosphorus, while CO32- inhibits the removal of PO43- due to competitive adsorption. The adsorbed products of DWTS@ZEOLITE after saturation were analyzed, and the main combinations were Fe-P and Al-P. The DWTS@ZEOLITE was characterized by Brunauer Emmett Teller (BET), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray spectroscopy (SEM-EDS) etc. BET results show that the specific surface area of DWTS@ZEOLITE is 4.2751 m2/g. SEM-EDS results show that the surface of DWTS@ZEOLITE is rough and has obvious phosphorus peaks after reacting with phosphorus. Both XRD and XPS results indicated that the reaction of DWTS@ZEOLITE with phosphorus showed characteristic peaks of FePO4, AlPO4 and Ca(H2PO4)2. The Fe, Al, and Ca elements contained in DWTS@ZEOLITE are exchanged with phosphate ligands to achieve adsorption. Finally, Dynamic experiments show that DWTS@ZEOLITE has a good effect on phosphorus, and the saturated adsorption capacity can reach 1774.5 mg/kg. DWTS@ZEOLITE provides a method for the granulation of DWTS) and realizes the resource utilization of DWTSand zeolite.

A comprehensive review on the coagulant recovery and reuse from drinking water treatment sludge.

The main treatment unit in conventional systems for surface water is coagulation-flocculation (CF) process, which consumes huge quantities of coagulant, and produces large volume of sludge. The produced sludge is known as one of the components of water treatment sludge (WTS), which is considered as a global issue and hot topic require careful attention from the plant operators and sludge managers to be managed sustainably with applying an ecofriendly method. Among the suggested technologies, recovery and reuse of coagulants from WTS show the potential to decrease the waste disposal and chemicals usage for drinking water treatment significantly. So, this comprehensive review provides a useful insight into environmental and health problems of WTS, reports the sources, physicochemical properties of sludge, describes different sludge management methods by more focus on coagulant recovery (CR), which significantly point out the different aspects of WTS recovery and reuse, and eventually, economic evaluation of the CR process was also discussed. The results of this review confirm that coagulants can be recovered from WTS by different methods and also will be reused for multiple times in the removal of pollutants from water and wastewater. Moreover, the recovered coagulants can be used as building and construction materials, constructed wetlands substrate and other aims.

Mechanical performance and phase analysis of an eco-friendly alkali-activated binder made with sludge waste and blast-furnace slag

A new eco-friendly alkali-activated material (AAM) using two waste materials, including drinking water treatment sludge (DWTS) and ground granulated blast furnace slag (GGBFS), was developed in this study. DWTS is a by-product generated from drinking water purification processes. Using DWTS and GGBFS to manufacture alkali-activated binder to replace cement provides an economical engineering solution for these industrial wastes and alleviates adverse environmental effects of cement production. In this study, the workability, mechanical performance, durability, and microstructure properties of AAM-derived mortar were evaluated with different DWTS/GGBFS proportions and sodium silicate (SS) to sodium hydroxide (SH) ratios. Moreover, this study investigated the formation of hybrid tobermorite-like C-(A)-S-H and zeolite-like N-A-S-H phases on different mixtures. The results showed that mortar samples made with AAM containing the DWTS/GGBFS ratio of 40/60 and SS/SH ratio of 1.5 had the highest compressive strength (67 MPa). The porosity results analysed using mercury intrusion porosimetry showed that 40% DWTS contents could refine pore structure and promote geopolymerisation. The x-ray diffraction pattern and Fourier-transform infrared spectroscopy identified the hybrid C-(A)-S-H and N-A-S-H phases. The element analysis on the AAM matrix using the energy-dispersive x-ray spectroscopy technique demonstrated that the co-existence of these two phases could improve the mechanical performance and microstructure. In addition, the results obtained from backscattered electron images showed that excessive alumina in the samples with more than 60% DWTS might lead to an incomplete reaction and a porous gel structure.