R. Steudel, B. Eckert: Solid Sulfur Allotropes.- R. Steudel: Liquid Sulfur.- R. Steudel, Y. Steudel, M.W. Wong: Speciation and Thermodynamics of Sulfur Vapor.- I. Krossing: Homoatomic Sulfur Cations.- R. Steudel: Aqueous Sulfur Sols.- W.E. Kleinjan, A. de Keizer, A. J. H. Janssen: Biologically Produced Sulfur.

R. Steudel, B. Eckert: Solid Sulfur Allotropes.- R. Steudel: Liquid Sulfur.- R. Steudel, Y. Steudel, M.W. Wong: Speciation and Thermodynamics of Sulfur Vapor.- I. Krossing: Homoatomic Sulfur Cations.- R. Steudel: Aqueous Sulfur Sols.- W.E. Kleinjan, A. de Keizer, A. J. H. Janssen: Biologically Produced Sulfur.

Despite more than 200 years of sulfur research the chemistry of elemental sulfur and sulfur-rich compounds is still full of “white spots” which have to be filled in with solid knowledge and reliable data. This situation is parti- larly regrettable since elemental sulfur is one of the most important raw - terials of the chemical industry produced in record-breaking quantities of ca. 35 million tons annually worldwide and mainly used for the production of sulfuric acid. Fortunately, enormous progress has been made during the last 30 years in the understanding of the “yellow element”. As the result of extensive inter- tional research activities sulfur has now become the element with the largest number of allotropes, the element with the largest number of binary oxides, and also the element with the largest number of binary nitrides. Sulfur, a typical non-metal, has been found to become a metal at high pressure and is even superconducting at 10 K under a pressure of 93 GPa and at 17 K at 260 GPa, respectively. This is the highest critical temperature of all chemical elements. Actually, the pressure-temperature phase diagram of sulfur is one of the most complicated of all elements and still needs further investigation.

In the context of wastewater treatment, Bioelectrochemical Systems (BESs) have gained considerable interest in the past few years, and several BES processes are on the brink of application to this area. This book, written by a large number of world experts in the different sub-topics, describes the different aspects and processes relevant to their development. Bioelectrochemical Systems (BESs) use micro-organisms to catalyze an oxidation and/or reduction reaction at an anodic and cathodic electrode respectively. Briefly, at an anode oxidation of organic and inorganic electron donors can occur. Prime examples of such electron donors are waste organics and sulfides. At the cathode, an electron acceptor such as oxygen or nitrate can be reduced. The anode and the cathode are connected through an electrical circuit. If electrical power is harvested from this circuit, the system is called a Microbial Fuel Cell; if electrical power is invested, the system is called a Microbial Electrolysis Cell. The overall framework of bio-energy and bio-fuels is discussed. A number of chapters discuss the basics – microbiology, microbial ecology, electrochemistry, technology and materials development. The book continues by highlighting the plurality of processes based on BES technology already in existence, going from wastewater based reactors to sediment based bio-batteries. The integration of BESs into existing water or process lines is discussed. Finally, an outlook is provided of how BES will fit within the emerging biorefinery area.