Ala. Admin. Code r. 335-7-6-.18

Current through Register Vol. 42, No. 12, September 30, 2024

Section 335-7-6-.18 - Filter Backwash Recycling

All systems that employ conventional filtration or direct filtration treatment and that recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet the following requirements:

(a) Reporting. A system must notify the state in writing by December 8, 2003, if the system recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes. This notification must include, at a minimum:

1. A plant schematic showing the origin of all recycled flows, the hydraulic conveyance used to transport them and the location where they are reintroduced back into the treatment plant. The schematic shall also show all treatment processes and all chemical addition points.

2. Typical recycle flow in gallons per minute (gpm), the highest observed plant flow experienced in the previous year (gpm), design flow for the treatment plant (gpm), permitted operating capacity for the plant.

3. Documentation proving the system can recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes and continuously produce water that meets the requirements of Rule 335-7-6-.04.

(b) Treatment technique requirement. Any system that recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet the following minimum treatment requirements:

1. All recycle flows must undergo independent clarification before being reintroduced to the treatment processes.

2. All recycle flows must enter the main raw water supply before this combined water source enters the plant's first treatment process.

3. Equipment must be installed to measure turbidity found in recycle flows before being introduced to the raw water supply, prior to the plant's first treatment process.

4. All capital improvements required to modify recycle processes, to meet these requirements, must be completed no later than June 8, 2006.

(c) Recordkeeping. The system must collect and retain on file, for a period of no less than 5 years, the following recycle flow information for review and evaluation by the Department beginning June 8, 2004:

1. Copy of the recycle notification and information submitted to the state under paragraph (a) of this section.

2. List of all recycle flows and the frequency with which they are returned.

3. Average and maximum backwash flow rate through the filters and the average and maximum duration of the filter backwash process in minutes.

4. Typical filter run length and a written summary of how filter run length is determined.

5. The type of treatment provided for the recycle flow.

6. Data on the physical dimensions of the equalization and/or treatment units, typical and maximum hydraulic loading rates, type of treatment chemicals used, average dose, frequency of use, and frequency at which solids are removed.

Author: Edgar K. Hughes

Ala. Admin. Code r. 335-7-6-.18

New Rule: Filed April 25, 2003; effective May 30, 2003. Repealed and New Rule: Filed November 7, 2005; effective December 12, 2005.

Statutory Authority:Code of Ala. 1975, §§ 22-23-33, 22-23-49, 22-22A-5, 22-22A-6.