Water Treatment Sludge Research Articles

Parametric study of coagulant recovery from water treatment sludge towards water circular economy.

This study aims to recover the used coagulants from two water treatment plants via acidification technique. The water treatment sludge (WTS) was acidified with sulfuric acid (H2SO-4) at variable normalities (0.5, 1, 1.5, 2.0 and 2.5 N). The surface morphology and functionalities of both recovered coagulants were analysed using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The performance of recovered coagulants was tested for turbidity removal in surface water treatment at different coagulant dosages and pH. It was found that the optimum normality of H2SO4 for recovered alum was 1.5 N, where 66% turbidity removal was recorded. The recovered PAC treated with 1.0 N H2SO4 indicated high turbidity removal percentage, which was 50.5%. The turbidity removal increased with increasing coagulant dosage. More than 80% turbidity removal was achieved with 40 mg/L dosage of recovered alum and recovered PAC. Maximum removal (85%) was observed with 50 mg/L dosage of recovered alum. For commercial coagulant, the turbidity removal was higher, with a difference of up to 6% in favor of recovered alum. The potential reuse of coagulants can be explored in order to reduce the operating costs and promotes the reduction of WTS disposal.

COMPARING PHOSPHORUS RECOVERY AND OPTIMUM TIME DIGESTION FROM SINGLE AND MIXING SUBSTRATES BY USING ANAEROBIC MESOPHILIC DIGESTION TECHNIQUE

Phosphorus (P) is considered a limited and non-renewable mineral source that is essential in our daily lives, especially for the agricultural industry to produce fertilizer. Food Waste (FW), Palm Oil Mill Effluent Sludge (POMES), and Water Treatment Sludge (WTS) are wastes that are claimed to contain nutrients such as P. One of the methods that can be used to recover P is through the Anaerobic Mesophilic Digestion (AMD) technique. Therefore, this study was carried out to investigate the highest P recovery and time digestion from single and mixing substrates. The physicochemical and biological properties of raw FW, POMES, and WTS were determined, and it was reported that wastes were suitable to undergo the AMD process. Mesophilic conditions 350C (±1) were used as the appropriate conditions for the anaerobic bacteria (AB) to reproduce and grow. Results for single substrates found that POMES recovered the highest P with 57.88% (±1.24), and optimum digestion was at day 12. While FW and WTS recovered P with 31.94% (±0.76) and 26.47% (±1.51), respectively, the optimum digestion times for both wastes were at days 18 (FW) and 21 (WTS), respectively, which were longer than POMES. In mixing substrates, FW-POMES contributed to the highest P recovery value with 68.34% (±1.49), and the optimum time digestion was on day 9. Followed by WTS-POME, FW-WTS, and FW-POMES-WTS with values of 60.42% (±2.12) (day 15), 48.05% (±2.51) (day 8), and 20.85% (±1.33) (day 3), respectively. The better synergetic effect within anaerobic bacteria (AB) in mixing substrates with FW-POMES could eventually influence the highest P removal from the substrate in a short period of time. Moreover, this study also provides information on new strategies used in recovering P. Keyword(s) : Phosphorus recovery, Food Waste; Palm Oil Mill Effluent Sludge; Water Treatment Sludge; Anaerobic Mesophilic Digestion

Ecotoxicological aspects and environmental implications of the use of water and sewage treatment sludges

Ecotoxicological aspects and environmental implications of the use of water and sewage treatment sludges

Ceramic adsorbent material in removing reactive blue bf 5G dye from synthetic wastewater

This work evaluated the removal of the reactive blue BF 5G dye in Ceramic Adsorbent Material (CAM) prepared from Water Treatment Sludge (WTS). The CAM disks were treated at 480 °C. The materials were characterized regarding pH, electrical conductivity, moisture, solid and granulometric fraction, TGA, DSC, XRF, XDR, FTIR, SEM, BET and pH-PZC. The characterization reveals that CAM presented chemical and mineralogical composition promising for adsorption, with negative zeta potential, and a microporous and rough surface. Besides, the CAM has proven safe to produce and apply according to solubilization tests. The adsorption efficiency was evaluated regarding the effect of the pH, concentration of dye, number of CAM disks, and contact time. The best performance was achieved at pH3, with efficiency higher than 80 % after 48 h of treatment using 1 CAM disk and dye concentration between 1 and 30 mg·L−1. The equilibrium time varied between 24 h and 48 h according to the dye concentration. Kinetic, isotherm, and thermodynamic analyses showed that dye is spontaneously retained in the CAM by monolayer physisorption. This work shows that CAM can effectively remove the reactive blue BF 5G dye until the absence of color, which allows its correct disposal in the environment. Thus, this manuscript presents the preparation and application of a novel material, obtained from WTS, with potential to treat textile wastewater.

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.

Kinetic Study of Microbial Growth in Anaerobic Digestion of Solid Waste

Solid waste when discarded to the environment causes serious environmental problems. The kinetic study of microbial growth in anaerobic digestion process is process specific, yet, there are limited reported studies with regards to the feedstock’s (banana peel, chicken dung and waste water treatment sludge). The objective of the study is to carry out the kinetic study of microbial growth, and to know the conditions or environment responsible for the degradation of chicken dung, waste water treatment sludge and banana peel for the production of biogas and biofertilizer. The methodology involves the use of serial dilution, pour plating, cell counting for microbial population and Monod parameters were determined. Microsoft excel 2016 was use to carry out regression analysis, results shows that the maximum, growth rate (????????????????) estimated from the basic Monod equation, of microorganism, was 0.098 hr-1 and the half saturation constant, (????????), 1.2 ×108 mg/l. This pin point the availability of substrate for the survival of microorganisms

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.

Improving properties of bilge water’s treatment sludge in a port reception facility by novel continuous ultrasonic reactor

ABSTRACT The main problem faced by facilities dealing with bilge water treatment is the generation of a high sludge amount, which has significant contents of oil and hazardous substances. The presence of petroleum and petroleum-derived organic oil, which ranges from 10 to 20% in bilge water with varying characteristics not only poses challenges in treating the bilge water but also complicates the management of the bilge water treatment sludge. Hence, this study aims to improve the characteristics of treatment sludge generated after bilge water treatment at one of Turkey’s largest port waste reception facilities (PRF), consisting of a combined process involving ultrasound and a filter press. When the filter press was used to reduce the water content in the sludge cake to approximately 65%, a similar water content of about 65% was achieved by employing ultrasound as a pre-treatment, even when the initial sludge contained 95–98% water. Additionally, the application of ultrasound before the filter press did not have a significant impact on the values of total organic carbon (TOC) and loss on ignition (LOI). However, the value of dissolved organic carbon (DOC) decreased by 45% when subjected to sonication for 60 minutes at a density of 100 W/L. Furthermore, when ultrasound was applied as a pre-treatment, an increase in the sonication duration resulted in improvements of 10% and 22% in the parameters of total dissolved solids (TDS) and chloride, respectively, which were influenced by different levels of ultrasonic power. Briefly, such research has been novelly conducted on the management of bilge water treatment sludge. Ultrasound, which is often preferred in sludge dewatering applications, was applied to this type of sludge for the first time, and the studies were conducted in a pilot-scale facility and a real PRF field. In conclusion, the partially promising results of this study will provide a new alternative and a pioneering guide for the treatment of bilge water sludge.

CHARACTERISATION OF Moringa Oleifera FOR PURIFICATION OF TREATED WATER SLUDGE

Proper disposal of treated water sludge is one of the main challenges water treatment Plants are facing globally. This entails disposing of sludge in such a way that it will not be harmful to the environment due to the chemicals used during the treatment of the water. The disposal of sludge conditioned by chemical polymers has an adverse effect on health and the environment. The use of natural polymers (such as wool polymer) has been explored to reduce adverse effects that come from chemical polymers (polyurethane). Elemental compositions of Moringa Oleifera were distinctive using ultimate analysis, proximate Analysis, Fourier Transform Infrared Spectroscopy, and energy-dispersive X-ray fluoresce. Characterization was done to examine the composition, functional characteristics, and physico-chemical properties of moringa oleifera . The proximate result showed that Moringa oleifera contains 36.34% of crude lipids, 3.78% of moisture,4.08% of Ash, 4.70% of crude fibre, 29.56% of crude protein, and 21.54% of carbohydrate. The ultimate result showed that carbon contains 45.86% and hydrogen has 1.96%. FTIR Spectrum of Moringa Oleifera showed C≡N(carbon-nitrogen) C=N and S-S (Sulphur-Sulphur) stretching bond. FT-IR spectra showed the presence of protein and lipids components. The FTIR Spectrum of the dry sludge showed many vibrations indicating some functional groups like N-H in Amides, alcohols and amines O-H, (Oxygen-hydrogen) C≡C bond C=N, C-H(Carbon -Hydrogen)O-CH3, P-N-C, C-H in aldehydes and acids C=O in Carboxylic acids, and S-S bond ED-XRF showed the elemental composition of Moringa Oleifera; 0.018% Fe, 0.001% Cu, 0.003% Al 9.00%, 0.038% Mg etc. and that of the dry sludge as 9.22%, Fe2O3, 0.572% CuO, 9.63% Aluminum oxide, 29.96% Silicon Oxide, 2.57% magnesium oxide. Turbidity of the treated sample was reduced to the level of Nigerian standard (5NTU). Moringa Oleifera was discovered to be a viable and affordable alternative for conditioning of water treatment sludge.

Drinking-Water-Treatment Wastes as Sorption Materials for Purifying Aqueous Environments from Pollution. Part 1. Iron-Containing Water-Treatment Sludge. A Review

Drinking-Water-Treatment Wastes as Sorption Materials for Purifying Aqueous Environments from Pollution. Part 1. Iron-Containing Water-Treatment Sludge. A Review

Drinking-Water-Treatment Wastes as Sorption Materials for Purifying Aqueous Environments from Pollution. Part 2. Aluminum-Containing Water-Treatment Sludge. A Review

Drinking-Water-Treatment Wastes as Sorption Materials for Purifying Aqueous Environments from Pollution. Part 2. Aluminum-Containing Water-Treatment Sludge. A Review

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.

Investigation on removal of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) using water treatment sludge and biochar

This work assessed the adsorption performance of three common PFAS compounds (PFOA, PFOS and PFHxS) on two water treatment sludges (WTS) and two biochars (commercial biomass biochar and semi-pilot scale biosolids biochar). Of the two WTS samples included in this study, one was sourced from poly-aluminium chloride (PAC) and the other from alum (Al2(SO4)3). The results of experiments using a single PFAS for adsorption reinforced established trends in affinity - the shorter-chained PFHxS was less adsorbed than PFOS, and the sulphates (PFOS) were more readily adsorbed than the acid (PFOA). Interestingly, PAC WTS, showed an excellent adsorption affinity for the shorter chained PFHxS (58.8%), than the alum WTS and biosolids biochar at 22.6% and 41.74%, respectively. The results also showed that the alum WTS was less effective at adsorption than the PAC WTS despite having a larger surface area. Taken together, the results suggest that the hydrophobicity of the sorbent and the chemistry of the coagulant were critical factors for understanding PFAS adsorption on WTS, while other factors, such as the concentration of aluminium and iron in the WTS could not explain the trends seen. For the biochar samples, the surface area and hydrophobicity are believed to be the main drivers in the different performances. Adsorption from the solution containing multiple PFAS was also investigated with PAC WTS and biosolids biochar, demonstrating comparable performance on overall adsorption. However, the PAC WTS performed better with the short-chain PFHxS than the biosolids biochar. While both PAC WTS and biosolids biochar are promising candidates for adsorption, the study highlights the need to explore further the mechanisms behind PFAS adsorption, which could be a highly variable source to understand better the potential for WTS to be utilized as a PFAS adsorbent.

Use of Water Treatment Sludge in the Production of Building and Ceramic Materials

Use of Water Treatment Sludge in the Production of Building and Ceramic Materials

Phosphorus adsorption and organic release from dried and thermally treated water treatment sludge

The study investigated water treatment sludge (WTS) as a phosphorus (P) adsorbent and examined the release of organic matter during the P adsorption process. Previous studies indicated that WTS is an effective adsorbent for P but also releases organic matter, which may affect the organoleptic properties of treated water, but no study has characterised organic release and conducted an in-depth study on its behaviours. This study characterised the organic release during the P adsorption process from four different WTS samples. This study also offers results from a 60-day column experiment that indicate that WTS columns effectively removed the majority of P from the 2 mg/L feed solution. The total organic carbon (TOC) release was gradually reduced from 24.9 mg/L on day 1 to stable levels of 4.4 mg/L to 4.1 mg/L from day 22 onwards. After 60 days, when the organic matter was nearly exhausted, WTS columns were still effective in P adsorption from the solution. In addition, the thermal treatment of WTS at different temperatures was investigated to reduce TOC release and increase P adsorption. The results showed that thermal treatment not only minimized TOC release but also enhanced the P adsorption capacity of the sludge. In a 24-h batch experiment, WTS treated at 600 °C showed the highest P adsorption (1.7 mg/g) with negligible TOC release when compared to sludge treated at 500 °C WTS (1.2 mg/g), 700 °C WTS (1.5 mg/g) and dried WTS (0.75 mg/g). However, the release of inorganic compounds slightly increased after thermal treatment. Future studies could focus on determining whether the thermal processing of WTS which can enhance the WTS's adsorption to emerging pollutants like per- and poly-fluoroalkyl substances and other contaminants. The findings of this study could influence the management practices of water authorities and contribute to the water sector's sustainability objectives.

A State-of-The-Art Technical Review on Chemically Enhanced Primary Treatment Plant

This review paper aims to provide a comprehensive assessment of chemically enhanced primary treatment (CEPT) processes in wastewater treatment plants (WWTPs). The outdated and ineffective performance of existing treatment plants has raised concerns regarding public health and environmental safety. CEPT has emerged as a promising alternative approach to enhance the efficiency and effectiveness of primary treatment. By adding chemical coagulants or precipitants to the wastewater, CEPT facilitates the aggregation and settling of suspended solids and contaminants, leading to improved treatment outcomes. This review evaluates the performance and effectiveness of different chemical coagulants, including ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum, in terms of their ability to remove various pollutants such as suspended solids, turbidity, organic matter, nutrients, and emerging contaminants.
 The findings from the reviewed studies indicate that different coagulants exhibit varying efficiencies in removing specific parameters such as turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and phosphorous. Alum, ferric chloride, and ferric sulfate showed effectiveness in tannery wastewater treatment, while PACl maximized the removal of macro pollutants. The use of organic carbon sources and sludge recycling demonstrated cost reductions and improved nutrient removal. CEPT was found to be effective in TSS and BOD removal, potentially allowing for compact treatment facilities and enhancing the capacity of biological treatment units. The utilization of recovered alum from water treatment sludge (WTS) in CEPT showed comparable efficiencies to fresh alum. The paper also identifies research gaps and future directions in the field of chemically enhanced primary treatment, while discussing the challenges and limitations associated with CEPT processes. While the reviewed studies provide valuable insights into the performance of different coagulants and coagulant aids, further research is necessary to assess their long-term effects and cost-effectiveness in large-scale applications. The optimal choice of coagulant depends on specific wastewater characteristics and treatment goals. Understanding and optimizing CEPT processes will contribute to the development of innovative solutions for challenges in wastewater treatment systems caused by urbanization, population growth, and emerging contaminants in the major city like Kathmandu.

Sorption properties of groundwater treatment residuals containing iron oxides

Drinking water treatment produces groundwater treatment residuals (GWTRs), which can be used as mineral sorbents. GWTRs, sometimes referred to as water treatment sludge or waterworks sludge, are by-products produced by drinking water treatment plants. Their disposal is problematic and costly due to environmental constraints and has provided the impetus for research into their reuse as mineral sorbents. The main constituents of the sludge are iron and manganese oxyhydroxides, with calcium carbonate and detrital quartz (Q) in minor amounts. In this study, we investigated the sorption capacity of GWTRs toward Cd(II), Cu(II), Pb(II), Zn(II), and Cr(III), determining the effects of contact time, temperature, initial metal concentration, and pH on metal sorption efficiency. GTWRs are very effective metal sorbents, sorbing from tens to up to 230 g of metal/kg of sorbent, depending on the metal. Optimal conditions for sorption are pH 5–8, a reaction time of 4–5 h, and temperature 298 K. Investigations of the material after sorption by X-ray diffraction (XRD), infrared spectroscopy (FTIR), photoelectron spectroscopy (XPS), scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) have provided insight into the nature of the interaction of metals with GWTRs and described the reaction mechanism. Metals are removed from the solution through the processes of inner-sphere adsorption on the surface of the precipitate, coprecipitation with iron compounds and incorporation into the ferrihydrite (Fh) structure or precipitation in the form of their mineral phases, such as carbonates, metal oxides or hydroxides. The results obtained from the experiments show that GWTRs effectively remove metal cations from aqueous solutions and can be used as sorbents for pollutants from wastewater or liquid industrial waste. The next step should be to test the ability against anionic forms of metals and organic compounds.

Potential Use of Water Treatment Sludge as Partial Replacement for Clay in Eco-Friendly Fired Clay Bricks

The traditional production process of clay bricks involves the extraction of significant amounts of raw materials and consumes considerable energy, leading to anthropogenic greenhouse gas emissions and environmental degradation. Using environmentally friendly materials in the construction industry has become an attractive alternative for mitigating sustainability issues. One such alternative is incorporating waste materials, such as water treatment sludge (WTS), into clay brick production. This research aims to assess the viability of using WTS as a replacement for conventional clay in fired clay brick production, thereby mitigating environmental pollution. Five distinct mixtures were created, with WTS replacing clay at 0, 20, 40, 60, and 80% ratios. The mechanical properties and durability of the produced bricks were analyzed through various tests, such as Atterberg limits, optimum water content, unconfined compression, apparent porosity, compressive strength, flexural strength, density, water absorption, and efflorescence. The results demonstrated that as WTS content increased, Atterberg limits and apparent porosity increased. The bulk density, compressive strength, and bending capacity of the specimens were found to decrease as the WTS replacement ratio increased. Additionally, moderate efflorescence was observed in samples with higher sludge ratios.