The anaerobic methane fermentation process is able to be used for a wide variety of applications. These applications are in various stages of development - from proven technologies to developing technologies. Municipal and industrial wastewater treatment fall in between these extremes; they are developed, but not fully proven. This paper concentrates on these two applications in terms of obstacles to their full implementation. While much progress has been made in the use of anaerobic treatment for municipal and industrial wastewater treatment the development and implementation has not been as quick as was expected by numerous researchers and practitioners. Possible reasons for this delay are discussed. Perhaps the most significant obstacle is lack of experience with the process. In reviewing the history and subsequent development of sanitary engineering, it can be seen that engineering practice often has to run ahead of basic science to resolve sanitation challenges. Because of this, there is often a long lag time between the implementation of technology and a rational design procedure for that technology. Rational design procedures are needed to build and operate reliable, economic, wastewater treatment processes. This assures credibility for the engineers and the operators of such technologies. Rational design must depend on both advances in basic science as well as accumulated operating experience and, ultimately this takes time.