| Integration of low pressure membrane processes (microfiltration and ultrafiltration) and powdered activated carbon (PAC), termed as the hybrid process, is currently under development in the field of drinking water treatment. While membranes allow the separation of PAC and particulate matter from treated water, the PAC is used for the removal of dissolved organic matter in the form of biodegradable organic carbon and also to remove traces of organic compounds (pesticides).;This project involves the application of respirometry to the case of biological powdered activated carbon (PAC). The main aims were to characterize the biological activity and quantify heterotrophic aerobic biomass (Z BH) colonizing the surface of activated carbon powder.;Activated carbons from three different sources were tested using respirometer Challenge AER-200, PAC 25 and 200 im (PAC-laboratory) and BAC (GAC-Ste Rose WTP) colonized in the laboratory using yeast extract, or PAC 25 mum (PAC-Opaline) from the biomembrane pilot Opaline-B (located at the Ste Rose treatment plant) colonized naturally with settled-ozonated water.;The microscopic observations of BacLight(TM) PAC-laboratory showed that coal 25 mum had more biomass per microscopic field than 200 im which was also demonstrated by the experimental results of respirometry. In addition, the comparison between the values of ZBH using 3 or 6 g of the same diameter of PAC have shown that the mass of 6 g had biomass concentrations higher than 3 g, which was consistent with expectations. However, PAC-laboratory of the two diameters were more colonized than the PAC-Opaline. As for the GAC-Ste Rose colonized in the laboratory for one week with yeast extract, it was more colonized than the PAC-Opaline but less than the PAC colonized in the laboratory.;To learn more about the process of biodegradation of substrate in hybrid membrane reactors, an estimate of bacterial activity and abundance is needed. Up to now, there are several methods to characterize the biomass on activated carbon (GAC), but no method applies to the case of PAC. However, respirometry, a method commonly used in the field of wastewater could be an interesting alternative due to its simplicity and low cost.;Following the experimental results, it was found that increasing the mass of PAC per bottle increased the rate of adsorption of oxygen by PAC and decreased the rate of bacterial respiration. We also found that autoclaving degas the saline solution and detached a portion of the biomass of the surface of PAC which further increased the rate of adsorption of oxygen. Following the development of the method, autoclaving and saline solution were successively replaced by sodium azide (1g/L) and dechlorinated tap water respectively. The yeast was chosen as the best carbon substrate since it had, within a single product, carbon, nitrogen, phosphorus and other micronutrients required for microorganisms growth.;The linear regression method used to quantify biomass colonizing the coal was found to depend on the lag phase, the type of substrate and the mass of PAC.;Finally, it was found that the Challenge AER-200 respirometer only measured bacterial consumption in the long term (above 6 hr), that is to say, it did not consider the short term bacterial activity (during the first few hours). Therefore, using a probe measuring the concentration of dissolved oxygen (DO) in continuous in the short term (less than 6 hr) has finally been privileged to the use of the Challenge AER-200. |
