Lake Water Treatment Plant Research Articles

Controlling Disinfection Byproducts at Maine Water's Mirror Lake Water Treatment Plant

Key TakeawaysWith elevated disinfection byproduct (DBP) levels in its distribution system, a water treatment plant in Maine worked with an engineering consultant to develop solutions and avoid possible regulatory violations.Four mitigation options were determined—two of them immediate and two long‐term, with the chosen strategy being premembrane coagulation.Recommendations from the success of the DBP mitigation project include being proactive, collaborating with team members and outside experts, and planning for resilience.

Potential Use of Wastewater Treatment Plant Sludge in Fabrication of Burnt Clay Bricks

Water treatment plants produce a huge amount of sludge, which are ultimately disposed to the nearest water channel, leading to harmful effects. This unmanaged wastewater treatment plant sludge (WTS) results in social and environmental concerns. Therefore, the utilization of WTS in construction activities can be a viable option for the management of waste sludge, leading to sustainable infrastructures. The main aim of this study was to investigate the potential of WTS in the manufacturing of clay bricks at an industrial scale. WTS was procured from the Rawal Lake water treatment plant, Pakistan. Clay was collected from a local industrial brick kiln site. Brick specimens with varying percentages of WTS (i.e., 5%, 10%, 15%, 20%, 30% and 40%) were casted and their mechanical and durability characteristics were evaluated. It was observed that the bricks incorporating WTS showed higher compressive and flexural strengths compared to that of the normal clay bricks. For instance, brick specimens incorporating 5% WTS by weight of clay showed a 10% increase in compressive strength. Furthermore, brick specimens incorporating 20% of WTS by clay weight satisfied the strength requirements as per local building codes for masonry construction. Scanning electronic microscopic (SEM) images confirm the porous microstructure of brick specimens manufactured with WTS, which results in 12% lighter clay bricks as compared to conventional clay bricks. Moreover, the durability characteristics of brick specimens incorporating WTS showed better performance. It can be concluded that bricks fabricated with a high proportion of WTS (i.e., 20%) will minimize the environmental overburden and lead to more durable and economical masonry construction.

Early warning method for cyanobacteria toxin, taste and odor problems by the evaluation of fluorescence signals

Permanganate and ozone are often used in drinking water treatment plants for the oxidation of taste and odor compounds, toxins, and algae as well as the reduction of mussel activity. The disadvantage of an overuse of such oxidants is the potential lysis of cyanobacterial cells. Cell lysis causes taste and odor components as well as toxins to be released into the water, which results in the need for even more treatment to remove these compounds completely. Our research in the CLIENT-SIGN project investigated an innovative method to monitor the lysis of cyanobacteria cells: increases in a specific fluorescence emission spectrum of the cyanobacteria pigment phycocyanin were used as a proxy for cell lysis and other compounds (taste/odor, toxins) leaving the cells. We call this form of phycocyanin “free phycocyanin” or “unbound phycocyanin”. By monitoring free phycocyanin via a relatively fast and inexpensive measurement, water utilities will be better able to optimize the dosage of pre-oxidation compounds to remove extracellular compounds while preventing the lysing of cells. Laboratory studies and a case study at Yangcheng Lake (adjacent to Lake Taihu, Yangcheng Lake Water Treatment Plant, Suzhou Industrial Park, China) are presented herein. An online surveillance system that monitors incoming raw water and the water after pre-oxidation is proposed to better cope with changing water conditions.

Manganese removal by hydrogen peroxide and biofiltration

Biofiltration has gained more attention as an alternative filtration for the removal of manganese (Mn) in both groundwater and surface water. This study investigated the potential of biofiltration as pretreatment at the Bennery Lake Water Treatment Plant located in Halifax, Nova Scotia, for the removal of manganese and dissolved organic carbon (DOC) from pH 6 natural lake water. A bench-scale study identified the effect of oxidant enhancement with hydrogen peroxide (H2O2), nutrient enhancement with phosphorus (P) and medium type (granular activated carbon (GAC) and anthracite) on a biofiltration system. Addition of both the nutrient, phosphorus (300–500 µg/l), and the oxidant, hydrogen peroxide (0·5 mg/l) enhanced the biofiltration performance, achieving 98% manganese removal and 27% (1·3 mg/l) DOC removal. Overall, the medium was not a significant factor for manganese removal, while GAC removed significantly more DOC than anthracite, although further treatment would be required for either medium to achieve lower DOC concentrations. These results show direct biofiltration of surface water at pH 6 can remove manganese below the 50 µg/l aesthetic guideline from a manganese loading of over 1 mg/l. This work highlights a potential mechanism and implication of biological roughing filtration technique for the removal of manganese and DOC from natural surface water.

Characteristics of C-, N-DBPs formation from nitrogen-enriched dissolved organic matter in raw water and treated wastewater effluent

The objective of this study is to clarify the relationships between the characteristics of dissolved organic nitrogen (DON) and disinfection by-products (DBPs) formation. Treated wastewater effluents from the Neihu wastewater treatment plant in Taipei City (TN) and source waters from the Tai Lake water treatment plant in Kinmen (KT) were evaluated. These water samples were fractionated to obtain 7 DON isolates with different characteristics. The DON isolates were freeze-dried and re-dissolved to different DON fraction solutions containing 10 mg-C/L of non-purgeable dissolved organic carbon (NPDOC). The DBPs formation potentials (DBPFPs) (trihalomethanes (THMs), haloacetic acids (HAAs), and nitrosamines) of different DON fraction solutions were then assessed with chlorine and monochloramine treatments. After fractionation schemes, mass concentrations of dried DON-enriched isolates ranged from 0.2 to 46.4 mg/L. Both TN effluents and KT raw waters had similar compositions of DON fractions except for the amounts of amphiphilic bases/neutrals (AMPB/N) isolates: hydrophobic acids (HPOA) > hydrophilic acids/neutrals (HPIA/N) > AMPB/N of KT raw waters > hydrophilic bases (HPIB) > amphiphilic acids (AMPA) > hydrophobic bases/neutrals (HPOB/N) > AMPB/N of TN effluents > amino acids (AA). For carbonated DBPs (C-DBPs), AA fraction treated with NaOCl formed the greatest amounts of C-DBPs (up to 1258.2 μg/L of THMs and 1140.6 μg/L of HAAs). For nitrogenated DBPs (N-DBPs), the AMPB/N fraction (DON = 1.4 mg-N/L) treated with NH2Cl was the most important precursor to form N-nitrosodimethylamine (NDMA) and generated up to 9238.0 ng/L of NDMA from KT raw water. Taking both DBP formation and organic composition into account, the HPOA (31.9%–38.4%)/HPIA/N (17.6%–35.7%) fractions and AMPB/N fraction (38.4%–93.9%) were the most important contributors to the overall C-DBPFPs and N-DBPFPs, respectively.

Comparing removal of trace organic compounds and assimilable organic carbon (AOC) at advanced and traditional water treatment plants

Stability of drinking water can be indicated by the assimilable organic carbon (AOC). This AOC value represents the regrowth capacity of microorganisms and has large impacts on the quality of drinking water in a distribution system. With respect to the effectiveness of traditional and advanced processing methods in removing trace organic compounds (including TOC, DOC, UV(254), and AOC) from water, experimental results indicate that the removal rate of AOC at the Cheng Ching Lake water treatment plant (which utilizes advanced water treatment processes, and is hereinafter referred to as CCLWTP) is 54%, while the removal rate of AOC at the Gong Yuan water treatment plant (which uses traditional water treatment processes, and is hereinafter referred to as GYWTP) is 36%. In advanced water treatment units, new coagulation-sedimentation processes, rapid filters, and biological activated carbon filters can effectively remove AOC, total organic carbon (TOC), and dissolved organic carbon (DOC). In traditional water treatment units, coagulation-sedimentation processes are most effective in removing AOC. Simulation results and calculations made using the AutoNet method indicate that TOC, TDS, NH(3)-N, and NO(3)-N should be regularly monitored in the CCLWTP, and that TOC, temperature, and NH(3)-N should be regularly monitored in the GYWTP.

Biodegradation of haloacetic acids in water treatment processes

Formation and degradation of haloacetic acids (HAAs) in Tai Lake Water Treatment Plant (WTP) in Kin-Men County, Taiwan, were evaluated in this study. The results showed that formation of HAAs after chlorination is a fast process. Owing to the presence of fairly high organic precursors in the raw water, a large amount of HAAs (up to 80 μg/L in summer) was formed after addition of the pre-chlorine, and only a small portion of the HAAs was removed during the coagulation, flotation, and rapid filtration units. However, more than 80% of HAAs were removed in slow sand filtration (SSF) unit. Laboratory batch filtration tests showed that the HAAs can not be effectively removed by conventional coagulation and filtration treatments. However, the HAAs in water was effectively removed by biodegradation in batch biodegradation tests using filter sands taken from the top of the SSF unit in Tai Lake WTP. For comparison with the results obtained in batch experiments, simulated SSF systems were also installed in laboratory to evaluate the effects of biodegradation for HAAs removal in filter columns. Results of parallel laboratory SSF column tests showed that HAAs was quickly degraded when the simulated SSFs have been operated for a suitable time to allow the microbial growth on the sand surface. In both batch and simulated SSF biodegradation treatments, the biodegradation rates for HAAs decreased as the number of halogen atoms increased. The results in this study demonstrated that biological degradation is the major mechanism responsible for HAAs removal in the SSF units.

Evaluation of biological stability and corrosion potential in drinking water distribution systems: a case study

The appearance of assimilable organic carbon (AOC), microbial regrowth, disinfection by-products (DBPs), and pipe corrosion in drinking water distribution systems are among those major safe drinking water issues in many countries. The water distribution system of Cheng-Ching Lake Water Treatment Plant (CCLWTP) was selected in this study to evaluate the: (1) fate and transport of AOC, DBPs [e.g., trihalomethanes (THMs), haloacetic acids (HAAs)], and other organic carbon indicators in the selected distribution system, (2) correlations between AOC (or DBPs) and major water quality parameters [e.g. dissolved oxygen (DO), free residual chlorine, and bacteria, and (3) causes and significance of corrosion problems of the water pipes in this system. In this study, seasonal water samples were collected from 13 representative locations in the distribution system for analyses of AOC, DBPs, and other water quality indicators. Results indicate that residual free chlorine concentrations in the distribution system met the drinking water standards (0.2 to 1 mg l(-1)) established by Taiwan Environmental Protection Administration (TEPA). Results show that AOC measurements correlated positively with total organic carbon (TOC) and UV-254 (an organic indicator) values in this system. Moreover, AOC concentrations at some locations were higher than the 50 microg acetate-C l(-1) standard established by Taiwan Water Company. This indicates that the microbial regrowth might be a potential water quality problem in this system. Higher DO measurements (>5.7 mg l(-1)) might cause the aerobic biodegradation of THMs and HAAs in the system, and thus, low THMs (<0.035 mg l(-1)) and HAAs (<0.019 mg l(-1)) concentrations were observed at all sampling locations. Results from the observed negative Langelier Saturation Index (LSI) values, higher Ryznar Stability Index (RSI) values, and high Fe3+ concentrations at some pipe-end locations indicate that highly oxidative and corrosive conditions occurred. This reveals that pipe replacement should be considered at these locations. These findings would be helpful in managing the water distribution system for maintaining a safe drinking water quality.

Application of biofiltration system on AOC removal: Column and field studies

The Cheng-Ching Lake Water Treatment Plant (CCLWTP) is the main supplier of domestic water for the Greater Kaohsiung area, the second largest metropolis in Taiwan. Biological activated carbon (BAC) filtration is one of the major treatment processes in CCLWTP. The objectives of this study were to evaluate the effectiveness of BAC filtration on water treatment in the studied advanced water treatment plant and its capability on pollutants [e.g., AOC (assimilable organic carbon), bromide, bromate, iron] removal. In this study, water samples from each treatment process of CCLWTP were collected and analyzed periodically to assess the variations in concentrations of AOC and other water quality indicators after each treatment unit. Moreover, the efficiency of biofiltration process using granular activated carbon (GAC) and anthracite as the fillers was also evaluated through a column experiment. Results show that the removal efficiencies for AOC, bromide, bromate, and iron are 86% 100%, 17%, and 30% after the BAC filter bed, respectively. This indicates that BAC filtration plays an important role in pollutant removal. Results also show that AOC concentrations in raw water and effluent of the CCLWTP are approximately 143 and 16 μg acetate-C l −1, respectively. This reveals that the treatment processes applied in CCLWTP is able to remove AOC effectively. Results of column study show that the AOC removal efficiencies in the GAC and anthracite columns are 60% and 17%, respectively. Microbial colonization on GAC and anthracite were detected via the observation of scanning electron microscopic images. The observed microorganisms included bacteria (rods, cocci, and filamentous bacteria), fungi, and protozoa. Results from this study provide us insight into the mechanisms of AOC removal by advanced water treatment processes. These findings would be helpful in designing a modified water treatment system for AOC removal and water quality improvement.

Assessing the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units

Wastewater reuse can significantly reduce environmental pollution and save the water sources. The study selected Cheng-Ching Lake water treatment plant in southern Taiwan to discuss the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units. The treatment units of this plant include wastewater basin, sedimentation basin, sludge thickener and sludge dewatering facility. In this study, the treatment efficiency of SS and turbidity were 48.35-99.68% and 24.15-99.36%, respectively, showing the significant removal efficiency of the wastewater process. However, the removal efficiencies of NH(3)-N, total organic carbon (TOC) and chemical oxygen demand (COD) are limited by wastewater treatment processes. Because NH(3)-N, TOC and COD of the mixing supernatant and raw water are regulated raw water quality standards, supernatant reuse is feasible and workable during wastewater processes at this plant. Overall, analytical results indicated that supernatant reuse is feasible.

Effectiveness of AOC removal by advanced water treatment systems: a case study

Recently, the appearance of assimilable organic carbon (AOC) in the water treatment system and effluent of the treatment plant has brought more attention to the environmental engineers. In this study, AOC removal efficiency at the Cheng-Ching Lake water treatment plant (CCLWTP) was evaluated. The main objectives of this study were to: (1) evaluate the treatability of AOC by the advanced treatment system at the CCLWTP, (2) assess the relativity of AOC and the variations of other water quality indicators, (3) evaluate the effects of sodium thiosulfate on AOC analysis, and (4) evaluate the efficiency of biofiltration process using granular activated carbon (GAC) and anthracite as the fillers. Results show that the averaged influent and final effluent AOC concentrations at the CCLWTP were approximately 124 and 30 μg acetate-C/L, respectively. Thus, the treatment plant had an AOC removal efficiency of about 76%, and the AOC concentrations in the final effluent met the criteria established by the CCLWTP (50 μg acetate-C/L). Results indicate that the biofiltration process might contribute to the removal of the trace AOC in the GAC filtration process. Moreover, the removal of AOC had a correlation with the decrease in concentrations of other drinking water indicators. Results from a column test show that GAC was a more appropriate material than anthracite for the AOC removal. Results from this study provide us insight into the mechanisms of AOC removal by advanced water treatment processes. These findings would be helpful in designing a modified water treatment system for AOC removal and water quality improvement.

The renewal of a large water intake pipeline at Lake Geneva

The capacity increase of the Prieuré lake water-treatment plant in Geneva (Switzerland) required a corresponding increase in capacity of the water intake facilities. Three alternatives were considered. The selected project consisted of a new 2000 mm diameter offshore intake pipeline with a total length of 3 km, linked to an existing pipeline on-shore. Due to the expected low subatmospheric pressures during transient flow, severe design criteria had to be established for the buckling stability of the pipe shell and special attention was given to the corrosion protection scheme of the selected steelpipe. This paper describes the design and construction of the project.

The renewal of a large water intake pipeline at Lake Geneva

The capacity increase of the Prieuré lake water-treatment plant in Geneva (Switzerland) required a corresponding increase in capacity of the water intake facilities. Three alternatives were considered. The selected project consisted of a new 2000 mm diameter offshore intake pipeline with a total length of 3 km, linked to an existing pipeline on-shore. Due to the expected low subatmospheric pressures during transient flow, severe design criteria had to be established for the buckling stability of the pipe shell and special attention was given to the corrosion protection scheme of the selected steelpipe. This paper describes the design and construction of the project.

Removal of Dissolved Natural Organic Matter from Source Water with Alum Coagulation

In this study, the effectiveness of enhanced alum coagulation for removal of natural organic matter (NOM) at various alum dosages and pH conditions was assessed for three source waters. Results from the laboratory jar tests at various conditions were compared. Tested pH ranged from 5.0 to 8.0, with alum dosages ranging from 60-120 mg l−1 for removal of dissolved NOM with various concentrations of dissolved organic carbon (DOC) and alkalinity. Alum coagulation profiles of the three source waters were also compared. For Cheng-Kung Water Treatment Plant (high DOC, high alkalinity), laboratory tests showed 50% DOC removal with alum dosage of 70 - 110 mg l−1 after acidifying the raw water to pH = 6. For Tai Lake Water Treatment Plant (high DOC, low alkalinity), laboratory tests showed that the highest DOC removal (∼50%) was achieved at an alum dosage of 80 mg l−1 at pH = 8 (natural condition). However, alum coagulation showed little DOC removal for source water from Kee-Lung River (low DOC, low alkalinity). Higher alkalinity in Cheng-Kung Reservoir accounts for the necessity to acidify the raw water before enhanced coagulation for optimum DOC removal.

Sources and Haloacetic Acid/Trihalomethane Formation Potentials of Aquatic Humic Substances in the Wakarusa River and Clinton Lake near Lawrence, Kansas

Gram quantities of aquatic humic substances (AHS) were extracted from the Wakarusa River−Clinton Lake Reservoir system, near Lawrence, KS, to support nuclear magnetic resonance (NMR) experimental studies, report concentrations of dissolved organic carbon (DOC) and AHS, define sources of the AHS, and determine if the AHS yield sufficient quantities of haloacetic acids (HAA5) and trihalomethanes (THM4) that exceed U.S. Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCL) in drinking water. AHS from the Wakarusa River and Clinton Lake originated from riparian forest vegetation, reflected respective effects of soil organic matter and aquatic algal/bacterial sources, and bore evidence of biological degradation and photodegradation. AHS from the Wakarusa River showed the effect of terrestrial sources, whereas Clinton Lake humic acid also reflected aquatic algal/bacterial sources. Greater amounts of carbon attributable to tannin-derived chemical structures may correspond with higher HAA5 and THM4 yields for Clinton Lake fulvic acid. Prior to appreciable leaf-fall from deciduous trees, the combined (humic and fulvic acid) THM4 formation potentials for the Wakarusa River approached the proposed EPA THM4 Stage I MCL of 80 μg/L, and the combined THM4 formation potential for Clinton Lake slightly exceeded the proposed THM4 Stage II MCL of 40 μg/L. Finally, AHS from Clinton Lake could account for most (>70%) of the THM4 concentrations in finished water from the Clinton Lake Water Treatment Plant based on September 23, 1996, THM4 results.