Design and Cost Benefits of the Design and Cost Benefits of the Hollywood Chemical Injection Facility

To Dose or Not to Overdose…

That’s the Million-Dollar Question!

Kevin Dour, PE, PMP

Agenda

§ System overview

§ Sampling and monitoring

§ Modeling recommendations§ Modeling recommendations

§ Design

§ Facility siting

§ System performance

§ Lessons learned

Brightwater Conveyance System

Explain proposed BW system here

Goals: No odors at the property line; Minimize corrosion

Sampling and Monitoring Study

§ Previous KC field inspection identify corrosion

§ Targeted purpose: identify odor and corrosion issues upstream of Brightwater(interceptors and structures)

§ Field data collection• Monitor H2S with Odaloggers• Grab sample – Dissolved sulfides, dissolved oxygen, temp, pH, BOD

§ Sulfide prediction model• Used to estimate dissolved sulfides in new Brightwater System.• Pomeroy and Parkhurst equations• Calibrated using representative data from the sampling and monitoring study

In 2003 and 2004 a sampling and monitoring study was developed to identify odor and corrosion issues in the existing interceptors and structures that would be intergrated into the BW conveyance system.Field data was collected during the dry weather season (May- September) to obtain wastewater characterstics and odor concentrations that could then be used to design future odor and corrosion control facilities.H2S gas in the headspace of structures was monitored using Odaloggers. Odaloggers are installed in the headspace of structures, such as diversion structures or manholes, and monitors and logs the time of day, temperature and H2S level. The H2S data was taken in 5 minute intervals.Grab samples were taken of the liquid stream, for dissolved sulfides, dissolved oxygen, temperature, pH, and BOD. These indicators give us an idea of the wastewater characteristic of the flow in the existing conveyance system that would then flow into the Brightwater Conveyance system. A sulfide prediction model was used to estimate the dissolved sulfides in the existing as well as in the new Brightwater System.

Sulfide Prediction Model

- 80.6 ppd of dissolved sulfides

- 60% sulfides generated in SVI

Sampling and Monitoring Study

§ Recommendations• Siting facilities• Design concentrations• Chemical usage (BioxideTM )

§ Hollywood Pump Station:• Install chemical injection• Continue to monitor corrosion along SVI & BWI• Design for inlet dissolved sulfide concentration of 1.5 mg/L at Hollywood

Sulfide Prevention

§ Sulfate-Reducing bacteria (SRB) forms sulfides from sulfates in the absence of oxygen

§ BioxideTM – Calcium nitrate • NFPA rating: Heath-1, Fire-0, Reactivity-0• Does not degrade• Does not require freeze protection

§ Prevents & removes sulfides• Interrupts SRB’s sulfate respiration• Cultivates sulfide oxidizing bacteria

Hollywood Chemical Injection - Design

§ Address existing and future odor and corrosion problem• Reduce downstream DS and H2S• Corrosion protection in existing system

§ Chemical injection system§ Chemical injection system• Dosage:

– 3.4 gallons Bioxide/lb dissolved sulfides– 2010 ADWF @ 1.5 mg/l peak dissolved sulfides

• 4,400 gallon storage tank• Diaphragm metering pumps

– Flow paced off Hollywood effluent flows– “Pacing constant” to adjust dosing to respond to high sulfides in the system

Kevin, make comment of how nitrates in Bioxide react with dissolved sulfides

Hollywood Chemical Injection - Design

§ Existing pump station site • Tight access• Within shoreline/wetland setbackssetbacks

§ Other facilities improvements:• Generator• Gate/flow modifications in Hollywood & York Diversion Structures• I&C upgrades/Brightwater

Access Pump Station Access Drive

Pump Station from Trail

Trail from Pump Station

Wetland from Property Line

Chemical Metering Pumps

Chemical Fill PortPumps Fill Port

BioxideTank

Containment Area/ Emergency Eyewash

Downstream Benefits

§ Interceptor Protection• Reduce dissolved sulfides in SVI• Reduce downstream H2S release at Woodinville PS and BWIand BWI• Control future corrosion in BWI and SVI

§ Balance cost of BioxideTM usage with intended benefits• Prevent chemical overdosing• Monitoring important

Downstream Benefits

§ North Creek Odor Control Facility• Facility upgraded prior to Brightwater going on line

• Complex flow management • Complex flow management impacts odor generation

• Existing carbon scrubber odor control system

• New biological scrubberinstalled

System Performance

§ Monitor chemical injection performance• Downstream H2S monitoring to assess chemical injection performance

• Chemical dosing goal: • Chemical dosing goal: – Maintain 0.1 mg/L nitrates in SVI (no dissolved sulfides)

– Dissolved sulfides zero at North Creek

§ Nitrate residual analyzers• Limited reading measurements

System Performance

§ Vapor phase treatment + chemical injection = symbiotic performance• Conducted H2S monitoring at North Creek to assess upstream chemical injection in June & August ’08upstream chemical injection in June & August ’08

• Average H2S reduced over 80% with chemical injection• Peak H2S reduced almost 60% with chemical injection

§ Bioscrubber:• Lower and less variable inlet H2S concentrations • Higher level of performance expected

No Chemical Injection (June 08)- Average H2S = 6.5 ppm - Peak H2S = 24.7 ppm

*Preliminary H2S monitoring at North Creek Diversion Structure

With Chemical Injection (Aug 08)- Average H2S = 0.8 ppm - Peak H2S = 10.0 ppm

Maybe this should be last?

Lessons Learned

§ Sampling and monitoring essential to siting and sizing odor/corrosion facilities

§ Chemical injection facility• Chemical delivery access• Chemical delivery access• Operation and control• Lifecycle costs ($/gal, delivery costs)

§ North Creek bioscrubber• Biological systems performance varies based on temperature, and inlet H2S (intermittent vs. continuous)

• Consider future performance testing by varying upstream chemical doses

A symbiotic approach to odor control increases efficiency and reliability!

Questions?