Pertinent Factors Involving Disinfection and Stabilization of Municipal Biosolids

The inactivation of pathogens in biosolids and residuals can be achieved to physical, chemical and biological stressors. The physical stressors include temperature, cavitation and radioactive irradiation (gamma and beta). The chemical stressors are associated with alkaline agents (raising the pH and causing exothermic reactions), acidic agents (lowering the pH and causing exothermic reactions), oxidation and reduction agents (destroying organics and stabilization of uncharged disinfectants) and non-charged disinfectants (required to disinfect helminth eggs and bacterial spores). The biological processes result in the temperature increases greater and result in the production of biocidal by-products such as organic acids, aldehydes and alcohols, which act as disinfectants. In general, biological residual treatment processes such as composting, anaerobic digestion, alkaline stabilization, lagoon storage and air drying, which involve multistressors factors and are generally more effective and economically viable.The understanding of stabilization is moving from the state of science in the 1970s to the 21st Century. This entails the control of putrescible organics with the potential destabilization of anaerobically digested biosolids. By understanding the role of oxidants in the stabilization processes, the approach to stabilizing biosolids is changing while utilizing the concepts in collection systems. In the more recent studies, the usage of oxidation-reduction potential is very useful in monitoring these systems along with the usage of Pearson soft acids such as chlorine dioxide and ferrate.