E2.02A Arachchige 2019 ReNUWIt Annual Meeting Poster

Over three years of stable performance of a pilot-scale version of the Photosynthetically Oxygenated Waste-to-Energy Recovery (POWER) system has been reported by us. Ability of this mixotrophic algal system in meeting discharge standards for dissolved organic carbon and nutrients in 2-3 days of fed-batch processing time has also been demonstrated. Recently, we have shown that the POWER system can achieve undetectable levels of pathogenic bacteria within 1 day. Dominant factors contributing to this remarkable inactivation have been identified as low pH, moderate temperature, and the combined effects of sunlight.
The current study investigated the interrelationship among the above factors in fecal coliform inactivation. First-order decay kinetics was assumed to predict fecal coliform colony counts as a function of pH, temperature, and sunlight. Experiments at temperatures above 45°C yielded the relationship for temperature-dependence of the inactivation coefficient as: 𝑘𝑇 = 0.05 × 1.08𝑒 (20−𝑇). pH dependence of the inactivation coefficient was derived as: 𝑘𝑝𝐻 = 936𝑒 -2.55pH. A simple relationship for the combined effects of sunlight was developed as: k1(t) = 0.01 + 0.6471(t) where, I(t) is the solar intensity to be integrated over the process time to obtain cumulative solar insolation.