Abstract
SUMMARYThe underutilized biomass and different organic waste streams are nowadays in the focus of research for renewable energy production due to the effusive use of fossil fuels and greenhouse gas emission. In addition, one of the major environmental problems is also a constant increase of the number of organic waste streams. In a lot of countries, sustainable waste management, including waste prevention and reduction, has become a priority as a means to reduce pollution and greenhouse gas emission. Application of biogas technology is one of the promising methods to provide solutions for both actual energy-related and environmental problems. This review aims to present conventional and novel biogas production systems, as well as purification and upgrading technologies, nowadays applicable on a large scale, with a special focus on the CO2 and H2S removal. It also gives an overview of feedstock and the parameters important for biogas production, together with digestate utilization and application of molecular biology in order to improve the biogas production.
Highlights
Biogas is a renewable energy source that can be produced from different cheap recycling organic waste streams combined with the reduction of greenhouse gases emission
Toldra et al [92] studied the effects of temperature and hydraulic retention time (HRT) on the treatment of dairy wastewater. They reported that reducing temperature decreased chemical oxygen demand (COD) removal efficiency from 10 % to 25 % and the bioreactor performance gradually increased with the increasing of HRT
Different biotechnological methods can be applied in high strength organic wastes treatment due to their low energy consumption, less residual sludge generation, and efficient energy recuperation
Summary
Biogas is a renewable energy source that can be produced from different cheap recycling organic waste streams combined with the reduction of greenhouse gases emission. Sludge retention bioreactors were constructed to operate at a short HRT and long SRT with the purpose to maintain high concentration and activity of microorganisms, improving the sludge stabilization and increasing the loading capacity of the system They have been modified in the sense to boost the rate of organic waste degradation, reduce retention time, and increase organic waste loading and biogas production [76]. The beginning of the anaerobic digestion can be prolonged because of the slow formation of granular sludge, which depends on operational conditions (pH, temperature, HRT) and used substrates (organic matter content) These drawbacks could be overcome by using a two-stage digestion systems [1,76] or UASB bioreactors with membrane-based retention of sludge granules [80]. Future optimizations of biogas production systems have to be based on the combination of different NGS methods for the study of microbial community dynamics and functional activities
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