This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book deals with the treatment of acid gases present in fumes from meat and bones meal and sewage sludge co-incineration. It describes rapid heating rates to gasify Clean Wood and two Refuse Derived Fuel samples using thermogravimetric analysis coupled to gas chromatography. The book explores the capability of supercritical waste gasification to convert the waste into marketable by-product. It explains municipal solid waste co-gasification technology and a new solid waste management scheme, which can minimize final landfill amounts and maximize material recycled from waste. The book presents multidirectional chemical instrumental activation analyses of dried sewage sludge as well as both solid and liquid by-products formed during sewage gasification in a fixed bed reactor which was carried out to assess the extent of that phenomenon.