Impact of recycling filter backwash water on organic removal in coagulation-sedimentation processes

Cyclodextrin Polymer-Loaded Micro-Ceramic Balls for Solid-Phase Extraction of Triazole Pesticides from Water

A citric acid cross-linked β-cyclodextrin (β-CD) polymer was synthesized and loaded on micro-ceramic balls to fabricate the solid-phase adsorbents (P-MCB) for adsorption and extraction of triazole pesticides from water. The stability of β-CD polymer and P-MCB was investigated in solutions with different pH values at different temperatures. The adsorption properties and the influence of kinetics, sorbent amount, pesticide concentration, and temperature on the adsorption capacity were evaluated. The results showed P-MCB had favorable adsorption of 15.98 mg/g flutriafol in 3.5 h. The equilibrium data followed the Freundlich equation, and the adsorption of flutriafol and diniconazole followed the second-order kinetics. The recovery rate of P-MCB for triazole pesticides in water was satisfactory, and the recovery rate was still 80.1%, even at the 10th cycle. The P-MCB had good stability, with a degradation rate of 0.2% ± 0.08 within 10 days, which could ensure extraction and recycling.

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.

Molecular characterization of disinfection byproduct precursors in filter backwash water from 10 drinking water treatment plants

Organic matter reacts with chlorine forming disinfection byproducts (DBPs) including trihalomethanes (THMs), haloacetamides (HAMs), haloacetic acids (HAAs), and haloacetonitriles (HANs). Filter backwash water (FBW) is either released back to the environment or recycled to the head of the treatment plant after solids settling and the remaining dissolved organic matter is a significant pool of DBP precursors that are not well understood. We characterized dissolved organic matter in FBW from 10 treatment plants and low molecular weight (MW < 1 kDa) organic matter contributed the most to DBP formation. We demonstrated overall similarity of the molecular composition (e.g., elemental ratios, m/z, DBE) of the 10 samples of FBW by Fourier transform ion cyclotron resonance mass spectrometry. Aromatic and more highly oxidized compounds preferentially reacted with chlorine, forming DBPs. Low MW (<450 Da) aliphatic compounds, and highly unsaturated and phenolic compounds were the primary precursors of THMs, HANs, and HAMs, and the formation potentials (FPs) of these groups of DBPs were correlated with multiple individual molecular formulae. HAA FPs were correlated with low MW, highly unsaturated and phenolic compounds. These advances in the understanding of the molecular composition of DBP precursors in FBW may develop the effective strategies to control DBP formation and limit impacts on the quality of finished water, and can be expanded to understanding DBP precursors in drinking water sources.

The photocatalytic process in the treatment of polluted water

Wastewaters often contain toxic organic pollutants with a possible adverse effect on human health and aquatic life upon exposure. Persistent organic pollutants such as dyes and pesticides, pharmaceuticals, and other chemicals are gaining extensive attention. Water treatment utilizing photocatalysis has recently received a lot of interest. Photocatalysis is cutting-edge, alternative technology. It has various advantages, including functioning at normal temperatures and atmospheric pressure, cheap prices, no secondary waste creation, and being readily available and easily accessible. This review presented a comprehensive overview of the advances in the application of the photocatalytic process in the treatment of highly polluted industrial wastewater. The analysis of various literature revealed that TiO₂-based photocatalysts are highly effective in degrading organic pollutants from wastewater compared to other forms of wastewater treatment technologies. The electrical structure of a semiconductor plays a vital role in the photocatalyst's mechanism. The morphology of a photocatalyst is determined by the synthesis method, chemical content, and technical characteristics. The scaled-up of the photoreactors will significantly help in curbing the effect of organic pollutants in wastewater.

Nature-based coagulants for drinking water treatment: An ecotoxicological overview

The intensive human activities extensively contaminated water sources making its treatment a problem of paramount importance, especially with the increasing of global population and water scarcity. The application of natural coagulants has become a promising and environmentally friendly alternative to conventional ones. This study was aimed at evaluating the efficiency of four plant extracts namely Agave americana, Carpobrotus acinaciformis, Austrocylindropuntia subulate, and Senicio anteuphorbium as natural coagulants to remove Microcystis aeruginosa cyanobacterium from water. The effects of pH (4, 5, 6, 7, 8 9, and 10) and coagulant dose (5, 10, 15, 20, 25, and 30 mg/L) on the coagulation efficiency were investigated. Results showed that plant-based extracts exhibited high coagulant abilities significantly contributing to the removal of M. aeruginosa cells up to 80% on a case-by-case basis. The ecotoxicity (Daphnia magna, Aliivibrio fischeri, Raphidocelis subcapitata, and Sorghum saccharatum) was absent or presented very slight acute toxicity up to 12.5 mg/L being S. anteuphorbium the least toxic. PRACTITIONER POINTS: Nature-based plant extracts showed removal rates up to 80%. Lower pH and A. subulate and S. anteuphorbium were the most efficient coagulants Toxicity effects were plant extracts-based and dose function. A. subulate and S. anteuphorbium were the least toxic extracts.

Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development

Release of pollutants due to inflating anthropogenic activities has a conspicuous effect on the environment. As water is uniquely vulnerable to pollution, water pollution control has received a considerable attention among the most critical environmental challenges. Diverse sources such as heavy metals, dyes, pathogenic and organic compounds lead to deterioration in water quality. Demand for the pollutant free water has created a greater concern in water treatment technologies. The pollutants can be mitigated through physical, chemical and biological methodologies thereby alleviating the health and environmental effects caused. Diverse technologies for wastewater treatment with an accentuation on pre-treatment of feedstock and post treatment are concisely summed up. Pollutants present in the water can be removed by processes some of which include filtration, reverse osmosis, degasification, sedimentation, flocculation, precipitation and adsorption. Membrane separation and adsorption methodologies utilized to control water pollution and are found to be more effective than conventional methods and established recovery processes. This audit relatively features different methodologies that show remarkable power of eliminating pollutants from wastewater. This review describes recent research development on wastewater treatment and its respective benefits/applications in field scale were discussed. Finally, the difficulties in the enhancement of treatment methodologies for pragmatic commercial application are recognized and the future viewpoints are introduced.

Metal-organic frameworks/alginate composite beads as effective adsorbents for the removal of hexavalent chromium from aqueous solution

Industrial waste discharge comprising heavy metals into potable water bodies induces many health hazards. This study investigates the role of metal-organic frameworks (MOFs) doped alginate beads (MOFs@ABs) as potential adsorbents for Cr(VI). Effects of pH, stirring rate, temperature, initial chrome concentration, and particles dosage on Cr(VI) adsorption are studied to evaluate adsorption ability of UiO-66@ABs for Cr(VI) removal from aqueous solution. The adsorption kinetics follows pseudo second order and the equilibrium isotherm is consistent with Langmuir isotherm model. The maximum adsorption capacity of UiO-66@ABs calculated from the model conforms to the experimental results. The desorption experiment of Cr(VI) adsorbed UiO-66@ABs (82%) demonstrates satisfactory regeneration efficiency. Based on our findings and comparative controlled experiments, the superiority of UiO-66@ABs promises their potential application in Cr(VI) removal from wastewater.

Formation and control of C- and N-DBPs during disinfection of filter backwash and sedimentation sludge water in drinking water treatment

Drinking water treatment plants (DWTPs) produce filter backwash water (FBW) and sedimentation sludge water (SSW) that may be partially recycled to the head of DWTPs. The impacts of key disinfection conditions, water quality parameters (e.g., disinfection times, disinfectant types and doses, and pH values), and bromide concentration on controlling the formation of trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and haloacetamides (HAMs) during disinfection of FBW and SSW were investigated. Concentrations of most disinfection byproducts (DBPs) and associated calculated toxicity increased with extended chlorination for both FBW and SSW. During chlorination of both FBW and SSW, elevated chlorine doses significantly increased THM yields per unit dissolved organic carbon (DOC), but decreased HAN and HAM yields, with minimum effect on HAA yields. Chloramine disinfection effectively inhibited C-DBP formation but promoted N-DBPs yields, which increased with chloramine dose. Calculated toxicities after chloramination increased with chloramine dose, which was opposite to the trend found after free chlorine addition. An examination of pH effects demonstrated that C-DBPs were more readily generated at alkaline pH (pH=8), while acidic conditions (pH=6) favored N-DBP formation. Total DBP concentrations increased at higher pH levels, but calculated DBP toxicity deceased due to lower HAN and HAM concentrations. Addition of bromide markedly increased bromo-THM and bromo-HAN formation, which are more cytotoxic than chlorinated analogues, but had little impact on the formation of HAAs and HAMs. Bromide incorporation factors (BIFs) for THMs and HANs from both water samples all significantly increased as bromide concentrations increased. Overall, high bromide concentrations increased the calculated toxicity values in FBW and SSW after chlorination. Therefore, while currently challenging, technologies capable of removing bromide should be explored as part of a strategy towards controlling cumulative toxicity burden (i.e., hazard) while simultaneously lowering individual DBP concentrations (i.e., exposure) to manage DBP risks in drinking water.

Application of coagulation-ultrafiltration-nanofiltration in a pilot study for Tai Lake water treatment

In this study, the inline coagulation was combined with ultrafiltration and nanofiltration (UF-NF) in a pilot study for Tai Lake water treatment. The results showed that the combination process was very effective for Tai Lake water treatment in terms of organic removal and membrane fouling control. With inline coagulation, no irreversible membrane fouling was observed for either UF or NF at fluxes of 65-90 and 22-26 L/(m²  hr), respectively. The membrane foulants were analyzed, and the results indicated that the low molecular weight fractions in the feed were main membrane fouling contributors for both UF and NF, where hydrophilic substances and proteins, as well as neutral substances and humic acids with polycarboxyl groups, contributed significantly to UF and NF membrane fouling, respectively. Compared with direct UF-NF filtration without coagulation, the coagulants could aggregate organic micromolecules for cake formation. With inline coagulation, the moving flocs could generate shear stress to scrub the membrane surface for fouling control of UF. Moreover, with inline coagulation, the organics removal efficiency could be further increased by 10%-20%. With NF, the permeate had a TOC concentration of less than 0.5 mg/L, satisfying the drinking water quality. Therefore, the coagulation-UF-NF is very useful for Tai Lake water treatment. PRACTITIONER POINTS: Inline coagulation-UF-NF for Tai Lake Water treatment is implemented. Inline coagulation can aggregate hydrophilic substances to reduce membrane fouling. Moving flocs produce shear stress for fouling control of UF-NF. Superior quality of permeate is achieved with the combined coagulation-UF-NF process.

Enhanced coagulation of low-turbidity micro-polluted surface water: Properties and optimization

Micro-polluted surface water with low turbidity and low content of dissolved organic matter (DOM) is usually inefficiently purified. In this work, a combined technique for the enhanced coagulation of this surface water was proposed and investigated using cationic grafted starch (St-G) and polyaluminum chloride (PACl) as co-coagulants, followed by a magnetic ion-exchange resin (MIER). St-G was fed before PACl, and this procedure not only efficiently removes turbidity but also largely reduces the doses of the two coagulants. MIER remarkably removed DOM, and raw water was effectively purified. The entire coagulation process was further optimized through response surface methodology based on a central composite design by using the doses of St-G, PACl, and MIER as input variables. The dose effects of the three chemicals on the coagulation performance for turbidity and DOM removal were examined, and the coagulation mechanisms, including the interactive effect among various chemicals, were discussed in detail. This work provided a new strategy for the efficient treatment of low-turbidity micro-polluted surface water by utilizing organic and inorganic co-coagulants with magnetic ion-exchange resin in practical applications.

Morphology-tunable WMoO nanowire catalysts for the extremely efficient elimination of tetracycline: kinetics, mechanisms and intermediates

The presence of antibiotics in aquatic environments has attracted global concern. The Fenton system is one of the most popular methods for eliminating antibiotics in aquatic environments, but the existing Fenton system is limited due to the potential for secondary pollution, and the narrow pH range (∼3-5). In this study, we report that the bottlenecks for high-strength tetracycline (TC) wastewater treatment under neutral conditions can be tackled well by a class of mixed-valence W/Mo containing oxides (WMoO-x) with tunable morphologies. Triethanolamine was selected as a structure-directing agent to control the morphologies of the catalysts going from ultrathin nanowires (UTNWs) to wire-tangled nanoballs (WTNBs). As a proof of concept, the most efficient catalyst in the batch samples, WMoO-1 ultrathin nanowires, was employed as a model material for TC degradation, in which the coordinatively unsaturated metal atoms with oxygen defects serve as the sites for TC chemisorption and electron transfer. As a result, 91.75% of TC was degraded in 60 min for the initial TC concentration of 400 μM. Furthermore, LC-MS analysis confirmed that the TC could be degraded to nontoxic by-products without benzene rings, and finally mineralized to CO2 and H2O. ICP-MS and cycle experiments showed the good stability and reusability of WMoO-1 UTNWs in the Fenton-like system. The findings of this work provide fresh insights into the design of nanoscale catalyst morphology and reaffirm the versatility of doping in tuning catalyst activity, extending the range of the optimal pH values to neutral conditions. This is significant for the expansion of the heterogeneous Fenton-like family and its application in the field of water treatment.

EDTA-Fe(III) Fenton-like oxidation for the degradation of malachite green

Industrial waste, urban sewage and aquaculture have led to severely increased grades of environment pollutants such as dyes, pesticides and fertilizer. The use of technologies for purifying contaminated waters can be difficult and toxic due to the anti-photolysis, anti-oxidation and anti-bio-oxidation characteristics of organic pollutants, and there is therefore a significant need for new approaches. Here, we report methods of Fenton oxidation and EDTA-Fe(III) Fenton-like oxidation which can be used to degrade malachite green (MG: a dye and antibiotic-like substance) from contaminated water. Compared with the degradation rate (59.34%) of the Fe(III)/H₂O₂ Fenton process, the EDTA-Fe(III) Fenton-like oxidation got a better degradation rate (92.7%) at neutral pH conditions. By conducting a series of parallel controlled experiments (changing parameters such as the reactant concentration, temperature, and pH), we report the relationships between the degradation effect and different parameters, and we fitted their pseudo first order kinetic curves. Furthermore, we repeated to adjustment of the concentrations of MG in solutions to test the cycle performance and catalytic activities of EDTA-Fe(III)/H₂O₂ system and it showed good repeatability in the first five rounds and all of them keep the degradation efficiencies greater than 80%. By conducting comparative spin-trapping electron paramagnetic resonance (EPR) experiments, we showed indirectly that the OH contributes to the degradation of MG. Additionally, the results of the EPR experiments showed that EDTA contributes to the generation of OH in the EDTA-Fe(III)/H₂O₂ Fenton-like system. By conducting total organic carbon (TOC) analysis experiments, we found that EDTA was also oxidized to some extent during the degradation of MG. In all, the findings of this work widen the range of the optimal pH values up to neutral condition for degradation of MG by use of EDTA-Fe(III) Fenton-like system. And this system could be used as one approach for the degradation of organic pollutants at neutral conditions and provide some initial information regarding EDTA-Fe(III) Fenton-like oxidations. It's significant for the expansion of the homogenous Fenton-like family and its application in the field of water treatment.

The shadow of dichloroacetonitrile (DCAN), a typical nitrogenous disinfection by-product (N-DBP), in the waterworks and its backwash water reuse

Dichloroacetonitrile (DCAN) is one of nitrogenous disinfection by-products (N-DBPs) with strong cytotoxicity and genotoxicity. In this study, the formation potential (FP) of DCAN was investigated in the samples of six important water sources located in the Yangtze River Delta. The highest formation concentration of DCAN was 9.05 μg/L in the water sample taken from Taihu Lake with the lowest SUVA value. After the NOM fractionation, the conversion rate of hydrophilic fraction to DCAN was found the highest. Subsequently, a waterworks using Taihu Lake as water source was chosen to research the FP variations of DCAN in the treatment process and backwash water. The results showed that, compared to the conventional treatment process, O/biological activated carbon (BAC) process increased the removal efficiency of DCAN from 21.89% to 50.58% by removing aromatic protein and soluble biological by-products as main precursors of DCAN. The DCAN FP in the effluent of BAC filters using old granular activated carbon was higher than that in the influent and the DCAN FP of its backwash water was lower than that in raw water. In the backwash water of sand filters, the DCAN FP higher than raw water required the recycle ratio less than 5% to avoid the accumulation of DCAN.

Evaluation of drinking water treatment combined filter backwash water recycling technology based on comet and micronucleus assay

Based on the fact that recycling of combined filter backwash water (CFBW) directly to drinking water treatment plants (WTP) is considered to be a feasible method to enhance pollutant removal efficiency, we were motivated to evaluate the genotoxicity of water samples from two pilot-scale drinking water treatment systems, one with recycling of combined backwash water, the other one with a conventional process. An integrated approach of the comet and micronucleus (MN) assays was used with zebrafish (Danio rerio) to investigate the water genotoxicity in this study. The total organic carbon (TOC), dissolved organic carbon (DOC), and trihalomethane formation potential (THMFP), of the recycling process were lower than that of the conventional process. All the results showed that there was no statistically significant difference (P>0.05) between the conventional and recycling processes, and indicated that the genotoxicity of water samples from the recycling process did not accumulate in 15 day continuous recycling trial. It was worth noting that there was correlation between the concentrations of TOC, DOC, UV254, and THMFPs in water and the DNA damage score, with corresponding R(2) values of 0.68, 0.63, 0.28, and 0.64. Nevertheless, both DNA strand breaks and MN frequency of all water samples after disinfection were higher than that of water samples from the two treatment units, which meant that the disinfection by-products (DBPs) formed by disinfection could increase the DNA damage. Both the comet and MN tests suggest that the recycling process did not increase the genotoxicity risk, compared to the traditional process.

Evaluation of a drinking water treatment process involving directly recycling filter backwash water using physico-chemical analysis and toxicity assay

Recycling the filter backwash water of a drinking water treatment plant (DWTP) was considered as a feasible method to enhance the efficiencies of pollutant removal and water conservation.

The removal characteristics of natural organic matter in the recycling of drinking water treatment sludge: Role of solubilized organics

To clarify the role of solubilized organics derived from drinking water treatment sludge (DWTS) in the elimination of natural organic matter (NOM) in the DWTS recycling process, a probe sonoreactor at a frequency of 25 kHz was used to solubilize the organics at varied specific energies. The coagulation behavior related to NOM removal in recycling the sonicated DWTS with and without solubilized organics was evaluated, and the effect on organic fractionations in coagulated water was determined. The study results could provide useful implications in designing DWTS recycling processes that avoid the enrichment of organic matter. Our results indicate that DWTS was disrupted through a low release of soluble chemical oxygen demand (SCOD) and proteins, which could deteriorate the coagulated water quality under the specific energy of 37.87-1212.1 kW h/kg TS. The optimal coagulation behavior for NOM removal was achieved by recycling the sonicated DWTS without solubilized organics at 151.5 kW h/kg TS specific energy. Recycling the sonicated DWTS could increase the enrichment potential of weakly hydrophobic acid, hydrophilic matter, and <3 kDa fractions; the enrichment risks could be reduced by discharging the solubilized organics. Fluorescent characteristic analysis indicated that when recycling the sonicated DWTS without solubilized organics, the removal of humic-like substances was limited, whereas removal of protein-like substances was enhanced, lowering the enrichment potential of protein-like substances.

Combining physico-chemical analysis with a Daphnia magna bioassay to evaluate a recycling technology for drinking water treatment plant waste residuals

Recycling water treatment plant (WTP) waste residuals is considered to be a feasible method to enhance the efficiency of pollutant removal. This study also evaluated the safety and water quality of a pilot-DWTP waste residuals recycling technology by combining physical-chemistry analysis with a Daphnia magna assay. The water samples taken from each treatment step were extracted and concentrated by XAD-2 resin and were then analyzed for immobilization and enzyme activity with D. magna. The measured parameters, such as the dissolve organic carbon (DOC), UV254 and THM formation potential (THMFPs) of the recycling process, did not obviously increase over 15 days of continuous operation and were even lower than typical values from a conventional process. The extract concentration ranged from 0 to 2 Leq/ml as measured on the 7th and 15th days and the immobilization of D. magna exposed to water treated by the recycling process was nearly equivalent to that of the conventional process. Both the superoxide dismutase (SOD) and the catalase (CAT) activity assay indicated that a lower dose of water extract (0.5, 1, 1.5 Leq/ml) could stimulate the enzyme activity of D. magna, whereas a higher dose (2 Leq/ml at the sampling point C3, R3, R4 ) inhibits the activity. Moreover, the SOD and CAT activity of D. magna with DOC and UV254 showed a strong concentration-effect relationship, where the concentration range of DOC and UV254 were 4.1-16.2 mg/L and 0.071-4.382 cm(-1), respectively. The results showed that there was no statistically significant difference (p>0.05) between the conventional and recycling treatment processes and the toxicity of water samples in the recycling process did not increase during the 15-day continuous recycling trial.

Coagulation efficiency and flocs characteristics of recycling sludge during treatment of low temperature and micro-polluted water

Drinking water treatment sludge, characterized as accumulated suspended solids and organic and inorganic matter, is produced in large quantities during the coagulation process. The proper disposal, regeneration or reuse of sludge is, therefore, a significant environmental issue. Reused sludge at low temperatures is an alternative method to enhance traditional coagulation efficiency. In the present study, the recycling mass of mixed sludge and properties of raw water (such as pH and turbidity) were systematically investigated to optimize coagulation efficiency. We determined that the appropriate dosage of mixed sludge was 60 mL/L, effective initial turbidity ranges were below 45.0 NTU, and optimal pH for DOMs and turbidity removal was 6.5-7.0 and 8.0, respectively. Furthermore, by comparing the flocs characteristics with and without recycling sludge, we found that floc structures with sludge were more irregular with average size growth to 64.7 microm from 48.1 microm. Recycling sludge was a feasible and successful method for enhancing pollutants removal, and the more irregular flocs structure after recycling might be caused by breakage of reused flocs and incorporation of powdered activated carbon into larger flocs structure. Applied during the coagulation process, recycling sludge could be significant for the treatment of low temperature and micro-polluted source water.

Natural organic matter removal by coagulation during drinking water treatment: a review

Natural organic matter (NOM) is found in all surface, ground and soil waters. An increase in the amount of NOM has been observed over the past 10-20 years in raw water supplies in several areas, which has a significant effect on drinking water treatment. The presence of NOM causes many problems in drinking water and drinking water treatment processes, including (i) negative effect on water quality by causing colour, taste and odor problems, (ii) increased coagulant and disinfectant doses (which in turn results in increased sludge volumes and production of harmful disinfection by-products), (iii) promoted biological growth in distribution system, and (iv) increased levels of complexed heavy metals and adsorbed organic pollutants. NOM can be removed from drinking water by several treatment options, of which the most common and economically feasible processes are considered to be coagulation and flocculation followed by sedimentation/flotation and sand filtration. Most of the NOM can be removed by coagulation, although, the hydrophobic fraction and high molar mass compounds of NOM are removed more efficiently than hydrophilic fraction and the low molar mass compounds. Thus, enhanced and/or optimized coagulation, as well as new process alternatives for the better removal of NOM by coagulation process has been suggested. In the present work, an overview of the recent research dealing with coagulation and flocculation in the removal of NOM from drinking water is presented.

Disinfection by-products in filter backwash water: implications to water quality in recycle designs

The overall purpose of this research was to investigate disinfection by-product (DBP) concentrations and formation potential in filter backwash water (FBWW) and evaluate at bench-scale the potential impact of untreated FBWW recycle on water quality in conventional drinking water treatment. Two chlorinated organic compound groups of DBPs currently regulated in North America were evaluated, specifically trihalomethanes (THMs) and haloacetic acids (HAAs). FBWW samples were collected from four conventional filtration water treatment plants (WTP) in Nova Scotia, Canada, in three separate sampling and plant audit campaigns. THM and HAA formation potential tests demonstrated that the particulate organic material contained within FBWW is available for reaction with chlorine to form DBPs. The results of the study found higher concentrations of TTHMs and HAA9s in FBWW samples from two of the plants that target a higher free chlorine residual in the wash water used to clean the filters (e.g., clearwell) compared to the other two plants that target a lower clear well free chlorine residual concentration. Bench-scale experiments showed that FBWW storage time and conditions can impact TTHM concentrations in these waste streams, suggesting that optimization opportunities exist to reduce TTHM concentrations in FBWW recycle streams prior to blending with raw water. However, mass balance calculations demonstrated that FBWW recycle practice by blending 10% untreated FBWW with raw water prior to coagulation did not impact DBP concentrations introduced to the rapid mix stage of a plant's treatment train.