THM Monitoring in Consecutive Drinking Water Systems

Transcription

1 THM Monitoring in Consecutive Drinking Water Systems Rick Bacon Rudy Mui Systems that Enable the Optimization of THM Control

2 Real-time TTHM Monitoring Applications Process Optimization Ø Ø Precursor dilution blending Precursor removal filtration, coagulation Ø TTHM remediation flushing, air stripping, mixing Water Quality Control (ISO 21000) Transfer certification (contract compliance) in Consecutive Water Systems

3 TTHMs Requirements in Consecutive Systems Over 51,000 consecutive systems in the USA with 940 systems serving over 50,000 in population. In general, the Stage 2 DBPR applies to the Retailer (CS) although it is the Wholesaler (WS) that determines the quality of water at transfer. Contracts between WS and CS frequently specify quantity and service pressure but rarely specify quality parameters but where they do contract compliance measurement is required.

4 Real-time TTHM Analysis for Local Water Quality Control and Consecutive System Monitoring

5 Real-time TTHM Analysis for Local Water Quality Control and Consecutive System Monitoring

6 Real-time TTHM Analysis for Local Water Quality Control and Consecutive System Monitoring

7 Real-time TTHM Analysis for Local Water Quality Control and Consecutive System Monitoring

8 Contract Compliance Monitoring - Agbar THM / ug/l THMs at Service Reservoir in NE Spain (#1) CHBr3 CHBrCl2 + CHBr2Cl CHCl3 TTHM Conc Mar 21- Mar 28- Mar 4- Apr 11- Apr 18- Apr 25- Apr 2- May 9- May 16- May Source: Miquel Paraira Faus, Director Water Quality

9 Contract Compliance Monitoring - Agbar THMs in Network Distribu on Node, in NE Spain (#2) CHBr3 CHBrCl2 + CHBr2Cl CHCl3 TTHM THM / ug/l Jun 22- Jun 29- Jun 6- Jul 13- Jul 20- Jul 27- Jul 3- Aug 10- Aug Source: Miquel Paraira Faus, Director Water Quality

10 Benefits of Real-time TTHM monitoring Aguas de Barcelona (Suez) has negotiated water quality terms with Aguas Ter Llobregat (ATLL) and ATLL is penalized when water quality falls below minimum agreed levels. Rapid changes in water quality can be readily identified and remedial actions taken by the retailer. Reduction/optimization of water s residence times in the network/ tanks. Blending with water from another source (RO plant, lower disinfectant demand, lower levels of precursors). (Much higher costs) Reduction of re-chlorination doses, when feasible. When THM monitored by your equipment is low (far from the regulated level), we can adjust our treatment (especially % water treated by RO and have important savings). - Miquel Paraira Faus. AGBAR

11 East Coast Retailer Results Total THM From the Wholesaler µg/l /27 4/16 5/6 5/26 6/15 7/5 7/25 8/14 9/3 9/23 Enabling the Optimization of THM Control 11

12 East Coast Retailer Benefits Demonstrated that poor water quality in the retail network was driven by poor quality imported water, Able to identify when imported water likely to generate excursion. EPA has agreed for water to be piped directly to customers and by pass storage reservoir when TTHM reach predetermined levels at transfer point, Able to switch source of imported water and to minimize use of this more expensive alternative.

13 West Coast Wholesaler Results 100 Total THM at the WTP into Distribu on 90 µg/l of 19 compliance points > 80 µg/l, Ranging from 82 to 96 µg/l /26 3/17 5/6 6/25 8/14 10/3 Enabling the Optimization of THM Control 13

14 West Coast Wholesaler Benefits Wholesaler able to demonstrate that water quality problems of retailer are a function of long residency times and poorly maintained infrastructure NOT of imported water. City has been able to determine that priority for investment is not wholesaler s treatment plant but in retailer s infrastructure.

15 WRF and EPA Recommendations* 1. WS s [Wholesaler] and CSs [Retailer] should work together to characterize DBP growth through the distribution system 2. WSs and CSs should develop co-ordinated monitoring schedules that allow characterization of DBP from the point of disinfectant addition to the entry point; to the WS system, to the CS distribution system and to the end points of both the WS and CS distribution systems 3. WS and CS should work together to establish water quality goals that allow both to achieve compliance with the Stage 2 DBPR. This could include target DBP precursor concentrations at the point of disinfectant addition or in the finished water as well as target DBP concentrations at the CS entry point On-line and real-time TTHM monitoring will facilitate considerably the execution of these recommendations * Evaluation of Disinfection Practices for DBP and Precursor Occurrence in Consecutive Systems Chowdhury et al.2009

16 Data Reliability: Labs vs. Online (Spiked Samples) 5 US-EPA Accredited Labs & 3 THM-100 Monitors Sample Water Spiked at TTHM 79.5 ug/l (60% CHCl 3 ) Lab 1 Lab 2 Lab 3 Lab 4 Lab 5 THM THM THM % Error CHBr % Error CHBr % Error CHCl3 % Error CHCl3 16

17 Questions Rick Bacon Rudy Mui Aqua Metrology Systems Limited (408) Enabling the Optimization of THM Control 17

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