The growing quantities of waste sludge generated in municipal and industrial wastewater treatment plants containing various organics and other contaminants require novel treatment technologies that are capable of achieving significant removal efficiencies and producing reusable sludge products. As a response, a large variety of advanced oxidation processes (AOPs) have been investigated to remove the present contaminants from wastewaters and limited cases of waste sludge. Multidisciplinary researches have been carried out accordingly. In this regard, electrochemical advanced oxidation processes (EAOPs) have emerged as novel environmental-friendly and effective treatment technologies for the elimination of several organic contaminants. Considerable validation of these methods has been performed at both the bench-scale and pilot-scale. Although a promising new technology, the mechanisms involved in the oxidation of organic compounds during electrochemical advanced oxidation processes and the corresponding environmental impacts have not been completely addressed until now. This book aims at the electrochemical advanced oxidation processes occurrence from different points of view, describing its related technologies, providing an assessment of the development and efficiency, and highlighting various aspects of waste activated sludge stabilisation and reuse accordingly in five chapters. In the first chapter a brief review to waste sludge stabilisation and reuse has been presented. The second chapter provides an overview to advanced oxidation processes. The third chapter describes the various electrochemical advanced oxidation methods. Chapter four presents and discusses the own experimental investigations results employing the Fered-Fenton EAOP. The modeling of the results of the own experimental studies results by means of Taguchi method and artificial neural networks has been performed in the fifth chapter. The main goal of this book is to gather different updated viewpoints according to the electrochemical advanced oxidation processes and to provide the own experimental studies results accordingly in order to present students, researchers, engineers and managers with useful knowledge in this regard.

Methanogenesis or biomethamation is a very impressive phenomenon which has noticeable effects on both natural and engineered environments. This process is held by methanogens, which produce methane as the major end product of their metabolism in a unique energy-generating process. The organisms received much attention because they catalyse the terminal step in the anaerobic breakdown of organic matter under sulphate-limiting conditions and are essential for both the recycling of carbon compounds and the maintenance of the global carbon flux on Earth. Furthermore, methane is an important greenhouse gas that directly contributes to climate changes and global warming. Hence, the understanding of the biochemical processes leading to methane formation is of major interest. This book focuses on the methanogenesis processes in natural and engineered environments with emphasis on mechanism recognition, modelling and resource management as well as its ecological impacts. The aim of this book is to examine methanogenesis from different points of view, describing scientific methods to minimize its hazardous impacts, providing an assessment of the existing technologies, and highlighting various aspects of bio-fuel production and cogeneration in seven chapters which have been prepared by authors from completely different professional areas and majors.