OBTAINING CHLORAMINATION APPROVAL

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1 OBTAINING CHLORAMINATION APPROVAL Stan Zachopoulos, MWH Ohio Section AWWA 2013 Annual Conference

2 SUMMARY This presentation describes actions taken with MWH assistance to obtain regulatory approval for implementation of chloramine treatment in accordance with the Ohio EPA s Guideline for Evaluation and Implementation of Chloramination (GEIC). These actions were documented in a Chloramination General Plan that was prepared for, submitted to and approved by the Ohio EPA.

3 OUTLINE Background / Objectives Justification of Chloramination Baseline Documentation Chloramination Demonstration Study Recommended Treatment Strategy Implementation Schedule Regulatory Approval

4 BACKGROUND / OBJECTIVES WTP Flow Schematic (Typical 2-stage lime/soda ash softening WTP) PAC Alum Lime Soda Ash CO 2 Pre-Cl 2 F Post-Cl 2 Surface & Ground Water SETTLING 1 SETTLING 2 FILTERS CLEARWELL Distribution System

5 BACKGROUND / OBJECTIVES WTP Approved Capacity Max-Day = 10 MGD Peak Hour = 15 MGD (H.S. Pumps) Daily Water Production 6-8 MGD

6 BACKGROUND / OBJECTIVES Issues/Concerns Levels of DBP (TTHM and HAA5) concentrations in distribution system Concern for compliance with RAA MCLs of Stage 1 D/DBP Rule and with LRAA MCLs of Stage 2 DBP Rule Optimization of treatment at the WTP and optimization of distribution system were not adequate for consistent regulatory compliance

7 BACKGROUND / OBJECTIVES Alternative treatment options considered: Chlorine dioxide disinfection Improved TTHM precursor removal Alternative source of supply Reduction of ph in the distribution system Reduction of free chlorine residual Ozonation and biological filtration Precursor removal through ion exchange GAC adsorption of TTHM precursors, and TTHM removal through aeration Alternatives were evaluated for reliability, feasibility and affodability

8 JUSTIFICATION OF CHLORAMINATION (Why this process is important) Chloramination Addition of ammonia to chlorinated water (after disinfection CT requirements are met with chlorine) to form chloramines as a disinfectant residual Three species formed upon contact of chlorine with ammonia NH 3 + HOCl NH 2 Cl + H 2 O (Monochloramine) NH 2 Cl + HOCl NHCl 2 + H 2 O (Dichloramine) NHCl 2 + HOCl NCl 3 + H 2 O (Nitrogen Trichloride) Reaction products depend on ph and Cl 2 :N ratio Cl 2 :N < 5 Monochloramine Cl 2 :N Nitrogen Chloride, Nitrate, Nitrogen Gas Cl 2 :N >7.6 Nitrogen Trichloride, Free Chlorine (Break Point Chlorination) ph low Dichloramine

9 JUSTIFICATION OF CHLORAMINATION Advantages of Chloramines Less reactive than free Cl 2 with organics in forming DBPs (such as TTHMs). Monochloramine residual more stable than free Cl 2 or ClO 2, providing better protection against bacterial re-growth Monochloramine residual more effective in controlling biofilms Fewer incidences of taste-and-odor complaints Choramines are inexpensive Easy to form More cost-effective than feasible alternatives.

10 JUSTIFICATION OF CHLORAMINATION Disadvantages of Chloramines Less strong disinfectants than Cl 2, O 3 and ClO 2. Cannot oxidize iron, manganese, and sulfide. Excess ammonia may lead to nitrification and loss of chloramine residuals Need to periodically convert to free Cl 2 for nitrification control Dichloramine and trichloramine are not as effective disinfectants as monochloramine. Chloramines must be formed on-site Need for monitoring of nitrification

11 JUSTIFICATION OF CHLORAMINATION Goal: Compliance with DBP rules and improved water quality Objectives that have to be met with chloramination: Combined chlorine residual > 1 mg/l TTHMs/HAA5 below MCL throughout entire system Compliance with all finished water standards Improved water aesthetics Improved distribution system operations (e.g. biofilms) Control costs

12 BASELINE DOCUMENTATION Data and information that could be used to develop approval criteria and to evaluate implementation of chloramination: Heterotrophic Plate Counts (HPCs) Total Coliforms and Cryptosporidium Disinfectant Residual Concentrations Disinfection profile TTHM/HAA5 Concentrations Evaluation for Sanitary Defects Evaluation of Source Water Quality Evaluation of TOC Removal Evaluation of Distribution System Optimization IDSE results (per Stage 2 DBP rule) Other Water-Quality Parameters

13 BASELINE DOCUMENTATION Additional Information Submitted to Ohio EPA Water production rates (1-year period) Chemical feed doses Water quality parameters of source and finished water: ph Turbidity Tot. Alkalinity Tot. Hardness Ca/Mg Hardness Cl 2 Residuals Fluoride Temperature Water Stability / Corrosion Control

14 TTHM DATA

15 HAA5 DATA

16 TOC CONCENTRATIONS

17 TYPICAL TOC REMOVAL TOC removal required = 15 to 25 % (per Stage 1 D/DBPR, based on source water TOC and Alkalinity) Actual TOC removal = 40%-57% (high TOC removal rates to 3.7 times more than required) Average finished water TOC = 1.9 mg/l (low conc s) High TTHM concentrations due to long contact time in distribution system and to high Cl 2 doses required to maintain free Cl 2 residual in distribution system Reducing chlorine dose alone not adequate for TTHM compliance Average ph value required for corrosion control = 9.2 (favors TTHM formation) System appears to be an ideal candidate for chloramination

18 CHLORAMINATION EVALUATION Typical Monochloramine Decay

19 CHLORAMINATION PRELIMINARY EVALUATION Typical DBP Formation

20 CHLORAMINATION DEMONSTRATION STUDY Evaluation Parameters Chlorine and ammonia doses (Cl 2 doses: 3, 5, 7 mg/l) Cl 2 :N ratios (3, 4, 5, 7) Contact times (1.5, 3 hours) Rate of DBP formation Two Series of Tests Chloramine demand and decay tests DBP formation tests Performed tests using non-chlorinated filtered water

21 TYPICAL NH 2 Cl DECAY TESTS (1.5-HOUR Cl 2 CONTACT)

22 TYPICAL NH 2 Cl CONCENTRATIONS AS % OF TOTAL N % of Total N NH2Cl (mg/l as N) NH2Cl (mg/l as N) 160 Chlorine Dose = 3 mg/l Cl:N Feed / Cl:N Total C1 (1.8/3.3) C2 (2.4/4.1) C3 (3/4.9) C4 (4.3/6.3) Time (Hours) Chlorine Dose = 5 mg/l C5 (1.8/3.1) C6 (2.4/4.2) C7 (3/5.3) C8 (4.3/7.4) Time (Hours) Chlorine Dose = 7 mg/l C9 (1.8/2.6) C10 (2.4/3.5) C11 (3/4.4) C12 (4.3/6.1) Time (Hours)

23 FINDINGS Required combined Cl 2 residual in distribution system = 1 mg/l (SWTR) Required combined Cl 2 residual in clearwell effluent > 1.5 mg/l Required free Cl 2 residual in clearwell effluent for CT compliance = 2 mg/l (existing clearwells - T>15 o C) Required chlorine dose = 4 mg/l for 1.5-hour contact; 4.5 mg/l for 3-hour contact (depending on source-water quality) Optimal Cl 2 :N ratio = 4.3 (14% NH 2 Cl decay in 6 days) Results from Test 2 (3-hour free Cl 2 contact) consistent with Test 1 (1.5-hour contact)

24 TYPICAL TTHM FORMATION TESTS

25 TYPICAL HAA5 FORMATION TESTS

26 RECOMMENDED TREATMENT STRATEGY (Based on Demonstration Study) Chemical Feed Rates PAC, Coagulant, Soda Ash, Lime, CO 2, Fluoride: The same Intermediate Cl 2 (control of bacterial growth on filters, better control of post filter Cl 2 dose): Reduce Cl 2 dose (leave only a small residual in filter effluent) Post Cl 2 : Target a free Cl 2 residual of 1.5 to 2 mg/l prior to ammonia addition Ammonia: Target Cl 2 :N ratio = 4.5 (1.12 mg/l NH 4 OH / 2 mg/l free Cl 2 residual) Clearwells Re-evaluate clearwell capacity to meet CT values (winter)

27 CONCEPTUAL CLEARWELL SCHEMATIC NH 4 OH Free Cl 2 Sampling NH 4 OH High- Service Pumps Combined Cl 2 Sampling Cl 2 Cl 2 Filtered Water

28 RECOMMENDED TREATMENT STRATEGY Disinfection Free chlorine as primary disinfectant (CT compliance) Chloramines as secondary disinfectant residual Two ammonia feed points (winter and summer) Critical conditions: Min free Cl2 residual = 2 mg/l Max ph value = 10 Lowest water temperature = 4 o C Max CT value = 64 mg/l x min

29 RECOMMENDED TREATMENT STRATEGY Ammonia Storage-and-Feed System Components Chemical: 19% NH 4 OH solution (1.47 lbs NH 3 /gal) Target Cl 2 :N Ratio: 4.5 Ammonia Feed Dose Range: mg/l Minimum Bulk Storage: 1,000 gal Transfer Pumps: 5 gpm each Day Tank: 50 gal Day Tank Weight Scale: 0-1,000 lbs Metering Pumps: Three gph each Neutralization Tank: 50 gal Free Chlorine Analyzers upstream of NH 3 feed points

30 TYPICAL STORAGE SYSTEM

31 TYPICAL FEED SYSTEM

32 IMPLEMENTATION SCHEDULE Monitoring Schedule (per Chloramination Guideline) Parameters to be tested: ph, Alkalinity, Temperature, Free and Combined Cl2 residual, Free and total Ammonia, Nitrate, Nitrite, Monochloramine, Dichloramine + Trichloramine, Total coliforms, HPC, T&O, TTHMs/HAA5, D.O. Sampling Locations: Source, Prior to ammonia, Tap, Distribution system Frequency: Depending and parameter and in compliance with applicable Regulations Minimum Public Notification General customers (through billing inserts, media) Special water users (Kidney dialysis process, Aquatic pet applications)

33 IMPLEMENTATION SCHEDULE Stake Holder Consultation Treatment System Operation Start-up Personnel training Treatment adjustments Source-water quality variations Treated water variations

34 TYPICAL OHIO EPA APPROVAL PROCESS o Document submittal to Ohio EPA o Ohio EPA provided comments/ questions o Ohio EPA comments were addressed o Ohio EPA approval of Chloramination o System start-up o Conduct post-startup sampling filed with OEPA o Preliminary results expected to indicate DBP results below MCLs

35 GENERAL CONCLUSION o Chloramination can be a viable option for maintaining compliance with DBP regulatory requirements

EPB 311- Strategies for Dealing with Groundwater Treatment Systems Having High Natural Ammonia

EPB 311- Strategies for Dealing with Groundwater Treatment Systems Having High Natural Ammonia Background The occurrence of ammonia (NH 3 ) in the water source is often associated with pollution due to