Biomethane from industrial and municipal wastewater

Remains of drainage systems to remove waste and latrines have been found in houses from the Mesopotamian Empire (3500-2500 BC); ancient Rome had its Cloaca Maxima, and there still exists a working 4000-year-old sewer system in Greece. Nevertheless, it was not until the late nineteenth century, and after a fourteenth-century long dark age, that it was recognized that municipal waste water needs to be removed from its origin and treated to prevent the outbreak of diseases (Lofrano and Brown 2010). Until then, wastewater had been discharged in surface water or so-called “night soil” (toilet waste) and collected and used for fertilization. Later, in the early twentieth century, biological oxygen demand (BOD) was introduced as a measure of pollution and the first wastewater treatment systems were installed. Recently, the recovery of nutrients, reuse of water, production of intermediates, and generation of energy have become important incentives for the treatment of wastewater from both industrial and municipal origins. This may be more feasible through separation at the source and improved design of water usage and treatment systems (Guest et al. 2009; Larsen et al. 2009). Aerobic treatment was and still is the main technology used for the treatment of municipal wastewater in the north and cold climate areas. In the twentieth century, the possible application of anaerobic systems for the treatment of industrial wastewater and municipal wastewater in warmer climates was recognized after the development of the upflow anaerobic sludge bed (UASB) system in Wageningen in the 1970s (Lettinga 2014; van Lier et al. 2015). Nowadays, with new treatment designs and the paradigm shift toward seeing wastewater as a source of valuable resources, the application of anaerobic technology may be expanded toward treating municipal sewage in cold climates as well. Anaerobic treatment has its advantages, for example, lower excess sludge production, high applicable loadings, and lower energy demands, combined with biogas production. Initially, those were the reasons for the application of anaerobic treatment. Nowadays, the fact that nutrients (N and P) are not destroyed (e.g., emitted as N2) but released as recoverable ions is considered an additional advantage, since this facilitates recovery. Therefore, anaerobic technology has a central role in existing and newly developed waste treatment systems (Figure 3.1). It is, however, important to consider that in most cases, posttreatment of anaerobic effluent is warranted to guarantee that limits for safe discharge of the effluent are met (von Sperling and de Lemos Chrenicharo 2002).