New Membrane and GAC Treatment Plant for TOC

RemovalAWWA California-Nevada Section

Brian Shoener

Provost & Pritchard Consulting Group

Fresno, California

October 2, 2013

Outline Background of existing operations

Problem

Alternatives

Solution

Issues

Results

Lessons

Background Two Water Sources

Reservoir Gravity feed to plant

Bad water quality

River Pumped to plant – Two

1000 HP pumps

Good water quality

Background Existing Treatment Plant

500 gpm (0.72 MGD)

Sedimentation basin No sludge removal

Two dual media pressure filters

Chlorine gas

1 MG storage tank Gravity feeds most of

system

Problem Reservoir

High TOC Up to 6.1 ppm

High turbidity Up to 144 NTU

Iron

Manganese

Problem River

Excellent water quality

But………

River flow must be above a certain rate

Pumping is expensive

Bacteriological concerns at low flow

Problem Plant cannot meet DBPs

and turbidity

THMs > 120

HAA5 > 180

Did pre-chlorinate –stopped due to DBPs

But… now causing manganese problems and biological growth in basins

Problem No room to expand

SRF and Prop 50 Funding

Alternatives Install clarifier

Allow coagulation /sedimentation to reduce TOC & turbidity

Membranes

Alternatives Additional TOC Removal &

DBP Reduction

Ion Exchange – Piloted for 2 weeks. Worked

Brine handling and disposal issues

Chloramines Not feasible. Complexity.

Distribution system – wells using chlorine

Public acceptance problems

Alternatives Additional TOC Removal &

DBP Reduction

Granular Activated Carbon Easy to operate

Helps taste and odor

Solution Clarifier, membrane and

GAC

How to build upgrades and keep plant operating?

Build clarifier and feed existing filters

Fill in existing ponds

Construct building for membranes and GAC

Solution

Solution Client wants to bid

three different membrane vendors

Design for largest membrane system

Ability to run all or a portion of flow thru GAC

Lesson Learned All vendors have

different:

Skid sizes

Inlet/outlet

orientations

Waste drains

Air compressors

Lesson Learned Chosen vendor would

not move feed pumps off skid.

Next vendor supplied inaccurate design drawings

Planned Operation 3 Modes

Normal – Thru clarifier and pumped to membranes

Bypass Pumped –Bypass clarifier and pumped to membranes

Bypass Gravity –Bypass clarifier and directly feed membranes

Startup Issues New membranes have air

assisted backwash draining. This affects:

Backwash every 30 minutes

CIP every 30 days

MW every 30 days

Causes high velocity discharge

Overwhelmed gravity drains

Startup Issues Variable pressure from

reservoir and flow restrictions due to influent pipe size

Limited flow to 560 gpm from reservoir

Caused issues with backwash return

Bypass gravity mode cannot provide enough flow to feed one skid and backwash the other

Acceptance Test First start up attempt

Worked through many alarms

Second attempt

Vendor replaced some valving

Completely redid vendor supplied program

Everything worked

Operational Results Clarifier alone with

existing filters produced excellent TOC results.

TOC Removal

5 mg/L raw water

3.5 mg/L after clarifier

1 mg/L after membranes

ND after GAC

It was all going well until……

It was all going well until……

Thank You Questions?