How to overcome anaerobic digestion technical limitations with ultrasound
Vergara, L. Swain, D. and Meila, J., Ultrawaves Global, UK
(free)
The generation and disposal of organic waste without adequate treatment will result in significant environmental pollution. Apart from health concerns for the people in the neighbourhood of disposal sites, degradation of waste leads to uncontrolled release of greenhouse gases (GHGs) into the atmosphere. In this context, anaerobic digestion (AD) offers potential benefits since AD facilities (ADFs) not only decrease GHGs emission but also reduce dependence on fossil fuels for energy requirements.
The anaerobic process has several advantages over other methods of waste treatment. Most significantly, it is able to accommodate relatively high rates of organic loading. With increasing use of anaerobic technology for treating various process streams, it is expected that industries would become more economically competitive because of their more judicious use of natural resources. Therefore, AD technology is almost certainly assured of increased usage in the future. The main disadvantage of AD may be found in a relatively slow degradation rate of the biomass. In conventional digesters, the residence time is typically about 3 weeks and more (depending on the digester type, fermentation, temperature, etc.), resulting in the necessity of large digester volumes. However, in order to improve the conventional AD process efficiency, Ultrawaves ultrasound (US) technology has demonstrated to be a very effective method. Indeed, sonication of the active bacterial biomass causes large shear stresses leading to cell lysis (destruction of cell walls and release of cell’s content into the medium), sonochemical conversion of complex organic compounds into simpler ones and increase of specific area of substrate particles, thus making thus the biodegradation of biomass faster and more effective.
This paper attempts to inform technically and economically about the quick evolution and development of the Ultrawaves technology within the ADFs market, that is, outside the water industry where Ultrawaves has already reached more than a hundred facilities.
Keywords: Greenhouse gases, anaerobic digestion, degradation rate, biomass, fermentation, ultrasound, sonication, active bacterial biomass, wastewater.
