Impacts of the Reduction of Nutrient Levels on Bacterial Water Quality in Distribution Systems

ABSTRACT This study evaluated the impacts of reducing nutrient levels on bacterial water quality in drinking water. Two American Water System facilities (sites NJ102a and IN610) with histories of coliform problems were involved, and each water utility received two pilot distribution systems (annular reactors). One reactor simulated the conventional treatment conditions (control), while the other reactor was used to assess the effect of biological filtration and subsequent reduced biodegradable organic matter levels on suspended (water column) and biofilm bacterial concentrations in the distribution systems. Biodegradable organic matter levels were reduced approximately by half after biological treatment. For site NJ102a, the geometric mean of the assimilable organic carbon concentrations was 217 μg/liter in the plant effluent and 91 μg/liter after biological filtration. For both sites, plant effluent biodegradable dissolved organic carbon levels averaged 0.45 mg/liter, versus 0.19 to 0.22 mg/liter following biological treatment. Biological treatment improved the stability of free chlorine residuals, while it had little effect on chloramine consumption patterns. High bacterial levels from the biological filters resulted in higher bacterial concentrations entering the test reactors than entering the control reactors. On average, biofilms in the model systems were reduced by 1 log unit (from 1.4 × 105 to 1.4 × 104 CFU/cm2) and 0.5-log unit (from 2.7 × 105 to 7.8 × 104CFU/cm2) by biological treatment at sites NJ102a and IN610, respectively. Interestingly, it required several months of biological treatment before there was an observable impact on bacterial water quality in the system, suggesting that the effect of the treatment change was influenced by other factors (i.e., pipe conditions or disinfection, etc.).

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Control of disinfection by-products and biodegradable organic matter through biological treatment

Revue des sciences de l eau ◽

10.7202/705150ar ◽

2005 ◽

Vol 5 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

H. M. Shukairy ◽

R. J. Miltner ◽

R. S. Summers

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

River Water ◽

Biological Treatment ◽

Ohio River ◽

Formation Potential ◽

Ozone Dose ◽

Chlorine Demand ◽

By Products ◽

Biodegradable Organic Matter

The optimal use of ozonation as a pretreatment process prior to biological treatment of Ohio River water was investigated at both the bench (batch) and pilot-plant (continuous flow) scale. The study focused on disinfection by-products (DBPs) and DBP precursor compounds and on the production of biologically stable water. Biotreatment was achieved using a bench-scale fixed-film reactor with sand acclimated to the raw Ohio River water. Ozonation was found to create a number of aldehydes, in particular formaldehyde, methyl glyoxal, glyoxal and acetaldehyde. With the exception of formaldehyde, a plateau in the aldehyde yield occurred at an ozone to total organic carbon (03/TOC) ratio of 0,7 mg/mg, while formaldehyde increased with increasing ozone dose. After biotreatment, the concentration of aldehydes were below 1 µg/1. Increasing ozone doses were also found to increase the assimilable organic carbon (AOC), by both NOX and P17 procedures, and the biodegradable dissolved organic carton (BDOC). The AOC values showed a maximum at about an 03/TOC ratio of 2 mg/mg, white the BDOC continued to increase with the highest ozone dose : an 03/TOC ratio of 2,8 mg/mg. Both ozonation and biotreatment were fond to decrease the chlorine demand by up to 75 % for ozonation and 55 % for biotreatment. Similar trends were found for the impact of ozonation and biotreatment on the precursor compounds for total organic halogen (TOX), total trihalomethanes (TTHMs) and total haloacetic acids (THAAs), as measured by the formation potential (FP) test : 12 mg/l chlorine, 7 days, 25 °C, 6.5-7.2 pH. An ozone dose of 0.4 03/DOC (mg/mg) decreased the TOXFP, TTHMFP and THAAFP by 28 %, 23 % and 33 %, respectively. Further increases in ozone only marginally increased the amount of the TOXFP and TTHMFP removed, white a maximum removal of 53 % of the THAAFP occurred at 03/DOC ratio of 0.87 mg/mg. Biotreatment of the nonozonated samples yielded 39 %, 38 % and 73 % removal of the TOXFP, TTHMFP and THAAFP, respectively. Biotreatment of the ozonated sample yielded a 30 to 50 % reduction in TOXFP and TTHMFP, while a constant level of 30 to 40 µg/l of THAAFP was achieved. Chloropicrin formation potential increased with ozone dose, but subsequent biotreatment reduced it to below 0.2 µg/l. Ozonation was Pound to oxidize chorine demand and the precursors for TOX, THM and HAAs. However, it created chloropicrin precursors, aldehydes and other biodegradable organic matter. Biotreatment was found to further reduce the chlorine demand, the precursors for TOX, THMs and HAAs and reduce the ozone created disinfection by-products.

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Removal of trihalomethanes from high organic matter water sources using aeration: a feasibility study

Water Quality Research Journal ◽

10.2166/wqrj.2020.016 ◽

2020 ◽

Vol 55 (2) ◽

pp. 184-197

Author(s):

Saeideh Mirzaei ◽

Beata Gorczyca

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Feasibility Study ◽

Distribution Systems ◽

Water Age ◽

Treated Water ◽

Canadian Guideline ◽

Viable Solution ◽

By Products

Abstract In this study, diffused aeration was applied to remove trihalomethane (THM) compounds from chlorinated, treated water containing high dissolved organic carbon (DOC) of 6.8 ± 1.2 mg/L. Increasing air-to-water volumetric ratio (rA/W) from 16 to 39 enhanced total THM (TTHM) removal from 60 to 70% at 20 °C and from 30 to 50% at 4 °C. Although bromodichloromethane has lower Henry's law constant than chloroform (CF), it was removed by a higher degree than CF in some aeration trials. Albeit obtaining high removals in aeration, TTHM reformed, and their concentration surpassed the Canadian guideline of 100 ppb in about 24 hours at 20 °C and 40 hours at 10 °C in all attempted air-to-water ratios. The water age in the system investigated in this study varied from 48 hours in midpoint chlorine boosting stations to 336 hours in the nearest endpoint. This study showed that THM removal by aeration is not a viable solution to control the concentration of these disinfection by-products in high-DOC treated water and in distribution systems where water age exceeds 24 hours; unless, it is going to be installed at the distribution endpoints.

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Suspended particles in the drinking water of two distribution systems

Water Science & Technology Water Supply ◽

10.2166/ws.2001.0089 ◽

2001 ◽

Vol 1 (4) ◽

pp. 237-245 ◽

Cited By ~ 12

Author(s):

V. Gauthier ◽

B. Barbeau ◽

R. Millette ◽

J.-C. Block ◽

M. Prévost

Keyword(s):

Water Quality ◽

Drinking Water ◽

Organic Matter ◽

Distribution System ◽

Distribution Systems ◽

Suspended Solids ◽

Suspended Particles ◽

Raw Water ◽

Remote Locations ◽

Dissolved Matter

The concentrations of suspended particles were measured in the drinking water of two distribution systems, and the nature of these particles documented. The concentrations of particulate matter were invariably found to be small (maximum 350 μg/L). They are globally in the very low range in comparison with dissolved matter concentrations, which are measured in several hundreds of mg/L. Except during special water quality events, such as turnover of the raw water resource, results show that organic matter represents the most important fraction of suspended solids (from 40 to 76%) in treated and distributed water. Examination of the nature of the particles made it possible to develop several hypotheses about the type of particles penetrating Montreal's distribution system during the turnover period (algae skeleton, clays). These particles were found to have been transported throughout the distribution systems quite easily, and this could result in the accumulation of deposits if their surface charge were ever even slightly destabilised, or if the particles were to penetrate the laminar flow areas that are fairly typical of remote locations in distribution systems.

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Natural organic matter removal by ion exchange at different positions in the drinking water treatment lane

Drinking Water Engineering and Science ◽

10.5194/dwes-6-1-2013 ◽

2013 ◽

Vol 6 (1) ◽

pp. 1-10 ◽

Cited By ~ 29

Author(s):

A. Grefte ◽

M. Dignum ◽

E. R. Cornelissen ◽

L. C. Rietveld

Keyword(s):

Water Quality ◽

Drinking Water ◽

Organic Matter ◽

Water Treatment ◽

Organic Carbon ◽

Natural Organic Matter ◽

Drinking Water Treatment ◽

Biological Stability ◽

Sand Filtration ◽

Slow Sand Filtration

Abstract. To guarantee a good water quality at the customers tap, natural organic matter (NOM) should be (partly) removed during drinking water treatment. The objective of this research was to improve the biological stability of the produced water by incorporating anion exchange (IEX) for NOM removal. Different placement positions of IEX in the treatment lane (IEX positioned before coagulation, before ozonation or after slow sand filtration) and two IEX configurations (MIEX® and fluidized IEX (FIX)) were compared on water quality as well as costs. For this purpose the pre-treatment plant at Loenderveen and production plant Weesperkarspel of Waternet were used as a case study. Both, MIEX® and FIX were able to remove NOM (mainly the HS fraction) to a high extent. NOM removal can be done efficiently before ozonation and after slow sand filtration. The biological stability, in terms of assimilable organic carbon, biofilm formation rate and dissolved organic carbon, was improved by incorporating IEX for NOM removal. The operational costs were assumed to be directly dependent of the NOM removal rate and determined the difference between the IEX positions. The total costs for IEX for the three positions were approximately equal (0.0631 € m−3), however the savings on following treatment processes caused a cost reduction for the IEX positions before coagulation and before ozonation compared to IEX positioned after slow sand filtration. IEX positioned before ozonation was most cost effective and improved the biological stability of the treated water.

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USE OF DISSOLVED ORGANIC MATTER BY MICROORGANISMS: FORMATION OF WATER QUALITY IN A POND OF A HIGH TROPHIC LEVEL

Fisheries ◽

10.37663/0131-6184-2020-5-25-29 ◽

2020 ◽

Vol 2020 (5) ◽

pp. 25-29

Author(s):

Anatoliy Sadchikov ◽

Sergey Ostroumov

Keyword(s):

Water Quality ◽

Organic Matter ◽

Organic Carbon ◽

Dissolved Organic Matter ◽

Trophic Level ◽

Aquatic Ecosystem ◽

High Trophic Level ◽

Bacterioplankton Community ◽

Algae And Bacteria

The role of algae and bacteria in the consumption and mineralization of dissolved organic matter (DOM) in a highly trophic aquatic ecosystem was studied. The phytoplankton and bacterioplankton community consumed 60% of added DOM in August and 56% of DOM in September. Of the uptaken DOM, a significant amount of organic carbon was mineralized. In August 42.7% and in September 29% of organic carbon (of the consumed organic matter) were used for respiration.

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A colony count model for the control of drinking water distribution systems

Revue des sciences de l eau ◽

10.7202/705248ar ◽

2005 ◽

Vol 9 (2) ◽

pp. 189-205

Author(s):

A. Kerneis ◽

A. Déguin ◽

M. Feinberg

Keyword(s):

Organic Matter ◽

Process Control ◽

Residence Time ◽

Distribution Systems ◽

Control Parameter ◽

Control Parameters ◽

Supply Water ◽

Biodegradable Organic Matter

The purpose of this study is to select a process control parameter for monitoring microbial regrowth in a network and to develop a more accurate and relevant quality control of supply water. Two parameters were examined as potential process control parameters: the water residence time in the network and the concentration of biodegradable organic matter. Residence time calculations were carried out and validated by tracer studies in a branched network and then in a simply looped network. The measurement of the natural dissolved organic carbon (DOC) consumption in the network was preferred to the determination of any in vitro biodegradation. The measurement of consumption requires the determination of DOC in treated water and in supply water. It is simpler and less expensive than other biodegradable organic matter determinations. A model for colony counts as a function of the residence time was developed in order to demonstrate that this parameter can be used for process controlling. This model was very well adjusted to data collected in a network in winter, spring and summer. This process control parameter was then used in order to locate and estimate the quantity of water whose colony counts exceed the European directive guide level. Accurate correlation measurements between colony counts and DOC consumed in the network were carried out in three distinct systems. No significant correlations were measured. For these three networks, biodegradable organic matter measurements based on DOC determinations were demonstrated to be unreliable process control parameters for monitoring bacterial regrowth.

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Modeling and characterization of natural organic matter and its relationship with the THMs formation

Global NEST Journal ◽

10.30955/gnj.001361 ◽

2016 ◽

Vol 18 (4) ◽

pp. 803-816 ◽

Cited By ~ 4

Keyword(s):

Water Quality ◽

Organic Matter ◽

Organic Carbon ◽

Natural Organic Matter ◽

Formation Mechanism ◽

Quality Characteristics ◽

High Rate ◽

Disinfection Process ◽

By Products

Natural organic matter (NOM) has been identified as the prominent precursor for disinfection by-products (DBPs) formation during chlorination. Various studies have shown that the characteristics of NOM influence the Trihalomethanes (THMs) formation mechanism. The present study represents NOM categorization in terms of total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance at 254 nm wavelengths (UV254) and specific ultraviolet absorbance (SUVA) to investigate the effects of NOM on THMs formation mechanism. The high rate of dependency was found for each representative of NOM with respect to water quality characteristics and operational condition of disinfection process. Values of SUVA and UV254 is drastically reduced with respect from higher to a moderate chlorine dose which represent the chlorine contact is more predominant with hydrophobic fractions of NOM. The value of SUVA is decreasing with respect to temperature and reaction time, which reveled higher rate of utilization for hydrophobic fractions of NOM. Predictive modeling approach was carried out using multiple regression analysis with the combination of two surrogates at each stage of modeling with help of operational condition of disinfection process and water quality characteristics. The R2 value of the model was found in the range of 0.927 to 0.937 from the developed model and a model could be recommended for prediction of THMs in drinking water.

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Organic characterisation tools for distribution system management

Water Science & Technology Water Supply ◽

10.2166/ws.2009.015 ◽

2009 ◽

Vol 9 (1) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

C. W. K. Chow ◽

Philipp Kuntke ◽

Rolando Fabris ◽

Mary Drikas

Keyword(s):

Water Quality ◽

Organic Carbon ◽

Distribution System ◽

High Performance ◽

Distribution Systems ◽

Management Strategies ◽

Molecular Size ◽

Quality Parameters ◽

Size Exclusion ◽

Treated Drinking Water

In this investigation, high-performance size exclusion chromatography (HPSEC) was used to characterise organic matter in treated drinking water at key sampling locations along two selected distribution systems (chlorinated and chloraminated). Other water quality parameters such as colour, UV254, dissolved organic carbon (DOC) and assimilable organic carbon (AOC) as measured by bacterial regrowth potential (BRP), were also determined. One of the aims of this work was to develop new tools to monitor organic character change along the distribution system in order to identify impacting factors and develop management strategies based on water quality change. This study used samples from two contrasting distribution systems with different disinfection regimes and organic characteristics together with samples generated from laboratory simulations. System 1 is a chlorinated distribution system and generally requires elevated chlorine dosage to meet the demand due to the high DOC level. System 2 is a chloraminated system with stable water quality, low DOC and low chloramine dose (mild oxidation). Molecular size distribution determination using HPSEC is a very informative technique in assessing treatment processes and in this study the appearance of a molecular peak at 1,700 Da that can be used as an indicator of biological activity in distribution systems was confirmed. The use of BRP values, for upstream and downstream samples in the distribution system, was found to be a good approach to assess biological impacts on water stability. The observed biological impact from the biofilms between the studied systems were particularly useful in confirming the organic characterisation results.

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Assessing the impact of dissolved organic carbon changes on disinfectant stability in a distribution system

Water Science & Technology Water Supply ◽

10.2166/ws.2002.0110 ◽

2002 ◽

Vol 2 (3) ◽

pp. 251-257

Author(s):

C. Campos ◽

Ph. Harmant

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Distribution System ◽

Distribution Systems ◽

Organic Matter Content ◽

Matter Content ◽

Quality Model ◽

Organic Carbon Concentration ◽

Concentration Changes ◽

The Impact

Maintaining disinfectant residuals throughout the entire water distribution system is considered an efficient strategy to guarantee the biological stability of drinking water as it flows from the plant to the customer tap. Dosed at the plant, the disinfectant disappears in the distribution system due to reactions with both water and pipe constituents. Among them, certain fractions of the organic matter content are directly responsible for the loss of disinfectant. This study presents an example of the impact of the organic matter UV absorbance on free chlorine decay for a surface water. In addition, this study illustrates the use of laboratory experiments together with a water quality model as a valuable tool to predict the impact of organic carbon concentration changes on chlorine residuals in interconnected distribution systems.

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