La. Admin. Code tit. 51 § XII-269

Current through Register Vol. 50, No. 11, November 20, 2024

Section XII-269 - Waste Filter Wash Water

A. Backwash water from surface water treatment and lime softening plants should have suspended solids reduced to a level acceptable to the state health officer before being discharged to a backwash reclaim tank and recycled to the head of the plant.

1. The backwash reclaim holding tank shall:

a. contain the anticipated volume of waste water produced by the plant when operating at design capacity;

b. for plants having two filters, have a holding tank that will contain the total waste wash water from both filters calculated by using a 15 minute wash at 20 gallons per minute per square foot;

c. for plants having more than two filters, size the holding tank appropriately depending on the anticipated hours of operation.

B. Spent filter backwash water, thickener supernatant and liquids processes may be allowed by the state health officer to be recycled into the head of the plant, provided that:

1. compliance is achieved under the requirements of Subchapter G (Filter Backwash Recycling) of Chapter 11 (Surface Water Treatment Rule) of Part XII of this code;

2. the recycled water should be returned at a rate of less 10 percent of the instantaneous raw water flow rate entering the plant;

3. the recycled water should not be recycled when the raw water contains excessive algae, when finished water taste and odor problems are encountered, or when disinfection byproduct levels in the distribution system may exceed allowable levels. Particular attention shall be given to the presence of protozoans such as Giardia and Cryptosporidium concentrating in the waste water stream; and

4. water utilities may need to treat filter waste water prior to recycling to reduce pathogen population and improve coagulation or avoid reclaiming filter wash water given the increased risk to treated water quality.

La. Admin. Code tit. 51, § XII-269

Promulgated by the Department of Health, Office of Public Health, LR 44344 (2/1/2018), effective 8/1/2018.

AUTHORITY NOTE: Promulgated in accordance with the provisions of R.S. 40:4.A.(8), 40:4.13.D.(1)(2) and 40:5.A.(2)(3)(5)(6)(7)(17).