This slide presentation outlines the successful operation of four membrane treatment plants on the island of Maui in the state of Hawaii. Maui water is
characterized as: "flashy" due to open feed
sources, streams and irrigation ditches;
typically high iron; and,
"difficult" to treat water. The four membrane facilities include: Lahaina 3 x 90 CMF;
Olinda 2 x 90 CMF;
Kamole 8 x 90 CMF; and,
Iao 3 x 90 CMF. Lahaina operational challenges include:
algae growth in Pre Sedimentation,
short filter runs and
frequent CIP's; and,
high color episodes in raw water,
25 true color units. Lahaina treatment solutions:
algae
- Stop return of decanted backwash water to
headworks;
Install a roof over basin to prevent algal growth,
initiate cleaning with H<sub>2</sub>O<sub>2</sub>;
High Color
- Addition of Aluminum Chlorhydrate to raw water.
Dosage 2-3 ppm. Olinda operational challenges include:
color removal
- True color of raw water 180 - 200 color units;
coagulant selection limited
- Very low raw water alkalinity water, typically < 10
- Ferric Chloride depresses pH
- Alum creates too large a floc and blinds membrane
- Cationic polymer not compatible with membranes
- Aluminum Chlorhydrate produces a small floc that
removes well from membrane; and,
fouling. Olinda treatment solutions included:
color removal -
true color of raw water 180 - 200 color units, and
Aluminum Chlorhydrate addition 18 - 21 ppm;
sludge production
- Sedimentation;
Membrane Fouling
- Process Audit, membrane autopsy result iron fouling, initiate cleaning regime with sodium metabisulfite. Kamole operational challenges include:
no Pre-sedimentation
- solids accumulation in modules;
large turbidity swings
- Average turbidity 2 - 5 ntu, and
rain event spikes 100 - 600 ntu;
algae in raw water; and,
fouling. Kamole treatment solutions included:
no Pre-sedimentation
- Regular process audits to insure backwash
effectiveness;
High Turbidity
- Aluminum Chlorhydrate dosage up to 15 ppm;
Algae
- Installed a modern traveling screen, and
initiated cleanings with H<sub>2</sub>O<sub>2</sub>; and,
fouling
- Initiate cleaning regime with sodium metabisulfite. Iao operational challenges included:
plant was originally intended to be
temporary;
no pretreatment; and,
no raw water feed water system. Iao treatment solutions:
no Pre-sedimentation/pre-treatment
- Installed modern self-cleaning strainer;
No Raw water feed system
- Regular process audits required to insure
backwash efficiency.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.6 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 32 |
| Published : | 03/01/2007 |
