La Center Wastewater Plant Overview

Transcription

1 Vancouver, WA July 12-14, 2016 La Center Wastewater Plant Overview Sue Lawrence City of La Center, WA July 2007 Introduction History Design Changing Circumstances Where To Get Help Optimization 1

2 History Built in 1967 Upgraded 9 times, including the MBR and recent solids processing Existing facility borders: Commercial Area Bridge La Center Bottoms Wetland Public Amphitheater Limited room for expansion! Design Small Foot Print 20 year at 8.7% growth Reliability & Flexibility Preselection of MBR Completed Solids Dewatering Improvements 2

3 Design Parameters Current $11.7 Mill 0.69 MGD Max Month (Membranes 0.84 MGD) 1.29 Peak Day (Membranes 1.68 MGD Peak Day) Phase 1B $1.95 Mill, 1.04 MGD Max Month (Membranes 1.68 MGD) 1.94 MGD Peak Day (Membranes 3.36 MGD Peak Day) Phase 2 would be for solids and it is estimated at $3.9 Million Phase 3 est $8.7 Million 2.25 MGD Max Month (Membranes 3.36 MGD) 4.20 MGD Peak Day (Membranes 6.72 MGD Peak Day) La Center Plant Schematic 6 3

4 Changing Circumstances Growth dropped from 8.7 % to less than 1% Casino Resort not constructed City Council requested a 10% reduction in expenditures 4

5 Review Budget Looked at what and where we could save money Electrical bills seemed high Compared expenses to SBR Electrical bills higher, overall close to the same Optimization System would be more efficient if we could take half of it offline Our system does not have that ability very easily Only operate what you need Not able to do it with current program 5

6 Operate only what you need System would be more efficient if we only used one MBR Didn t want to take one offline completely Tracked Air Flow used Forced one MBR offline so only one would run Alternated operating MBR Worked with Ovivo to adjust programming Tracked Air Flow Used Utilized the Process Trends to track where the most air was being used Looked for ways to reduce the usage Looked at other equipment in the plant 6

7 Difficulties with Existing Program Program would not put one basin online Using Level Control Two basins on in medium flow Drop Pre-Air basin too low MBR basins had minimum level setting to prevent them restarting too frequently Using Flow Control Two basins on in medium and/or low flow Drop Pre-Air basin too low Didn t adjust for recycle flows MBR basins start and stop frequently Forced MBR Offline We shut the permeate valves while operating This put the system into low permeate flow shutdown MBR would stay offline with alarms Problem is there is no standby basin available for higher flows or if other MBR has problems 7

8 How it Works Two year average of Operation and Maintenance expenses Not including labor expenses Before optimization MBR was over 13% less to operate 8

9 When we changed from the SBR to the MBR we realized a 92 % reduction in the pounds of Total Suspended Solids and 57 % reduction in the pounds of BOD discharged to the receiving stream. One of the biggest benefits is the reduction in biosolids The MBR produces about 32 % less 18 9

10 Results New program started end of January 2014 System runs only one basin normally Maintains levels correctly After starting optimization the MBR was about 19% less to operate Questions? 10