Extract from CSIR Report on Biocide.

SANS 241 analysis of polluted river water before and after treatment with Biocide solution.

The Plankenbrug River runs into the Eerste River in Stellenbosch and has been a source of controversy in the last years. The river is subject to faecal pollution from this area with the main source of bacterial contamination being unmanaged grey water as well as industrial and domestic sewage discharges.

In light of the above situation, samples of the Plankenbrug River water were collected and treated with Biocide solution at low concentrations. Indicator organisms were tested, pre and post treatment, and compared to the DWA irrigation water quality guidelines and the SANS 241 drinking water quality specifications.

After 30 minutes following the application of 0.2% Biocide to Plankenbrug River water, the irrigation water quality guidelines were met for E. coli and bacteria were eliminated to a standard acceptable for drinking water as shown in the table and figure below.

Sample description: Plankenbrug River water treated with Biocide solution

AMBIO Environmental Management (Pty) Ltd was approached by BLOO to assist with biocide testing against a raw sewage sample from Potchefstroom Local Municipality WWTW.

1. Scope of the test method

The biocide was measured against E.coli , faecal and total coliforms per 100ml. This method is used to determine the presence of faecal pollution in wastewater and ground water. Faecal coliform group and E. coli are used as indicator organisms to test the effectiveness of effluent disinfection in a wastewater treatment plant. While these organisms are generally harmless to us, they do live under the same conditions that human pathogens live. Since we cannot test for every pathogen in the effluent, we test for easily detectable indicator organisms. The assumption is that if we kill the indicator organisms then we most likely will kill the pathogens during effluent disinfection.

2. Summary of test method

Shake the sample well and filter 100ml of sample through the membrane filter funnel which retains the bacteria found in the sample. The filter membrane is placed on MFC and M-Endo agar and incubated for ±24 hours at 45±2°C. The blue colonies on MFC agar are then counted and recorded as E.coli/ faecal coliforms and purple colonies on M-Endo agar are counted and recorded as total coliforms.

4. Results

The results are counted in a 100ml Cfu

6. Pictures of the MFC and M-Endo agar plates

The pictures of the plates were taken before dosing and then 3hours after dosing. 6.1Control A and B

Biocide in 1A and 1B reduced 100000 E.coli colonies to 139 colonies after 3 hours dosing and reduced 10000 total coliforms to 865 only.

Biocide in 2A and 2B reduced 10000 E.coli and total coliforms colonies to 0 after 30 minutes of dosing.

Biocide in 3 A and 3B reduced 10000 E.coli to 98 after 2 hours and then reduced it to 0 after 3 hours. Then 10000 total coliform were reduced to 305 after 2 hours and then reduced to 0 after 3 hours of dosing.

Biocide 4 A and 4B reduced 10000 E.coli to 447 after 30 minutes then reduced it to 0 after 1 hour and the total coliforms were reduced to 612 after 30 minutes and then reduced to 0 after 1 hour.

Biocide 5A and 5B reduced 10000 E.coli and Total coliforms to 0 after 30 minutes of dosing.