Emerging perspectives on environmental burden minimisation initiatives from anaerobic digestion technologies for community scale biomass valorisation

Abstract

This paper provides an extensive review of anaerobic digestion (AD) systems, with a specific focus on community scale digesters for urban applications, processing either municipal organic waste exclusively or as mix feed. Emphasis is placed on reducing the systems scale environmental impact of AD technologies, including pre-and post-treatment stages, alongside biogas production. Developments to-date in AD system research in Europe and in the Asia region have been compared, providing a comprehensive evaluation of current practice, elucidating the areas of further potentials.The scope of this review is two-fold -one, covering AD technologies including a cohort of simple and integrated wet and dry systems, which can be operated as continuous flow designs in single-or multi-stages. Two, focusing more on practices in digestate handling that minimise environmental impacts arising from their storage and land application. From an environmental perspective, we note the following trends emerging in the literature for processing urban waste that need further exploitation: dry AD (60-85% moisture) is suitable for low organic loads, mainly owing to resource savings in terms of water usage; co-digestion has shown better buffering capability, especially for two-stage digestion of food-based feed stocks; separating the digestate into liquid/solid fractions is effective for handling postdigestion emissions, mainly for mitigating ammonia volatilisation to air and phosphate leaching to soil.We report responses to a survey, conducted for this review, highlighting the contemporary issues and challenges -with particular focus on the operational, social and management issues from an Indian perspective. There is need for follow-up of running plants to ensure their environmental performance. Such initiatives will have to consider managing of pollution footprints from AD, alongside the current drive for its widespread implementation for two incentives: greenhouse gas mitigation and fossil-fuel independence.

Metagenomics survey unravels diversities of biogas’ microbiomes with potential to enhance its’ productivity in Kenya

“…Over 30,000 industrial installations globally, have been revealed to utilize AD to convert organic wastes into permanent power production sources, amounting to10,000 MW [3]. Moreover, stable AD processes emerges as one of the efficient environmental model for organic wastes valorization, permitting nutrient recovery from the digestate [4], suggesting another economic benefits of AD systems [5], compared to other methods of wastes managements [6]. In addition, African countries, including Kenya, have proven to harbor huge amount of wastes [5], with high biogas generating potentiality.…”

Assessment and mitigation of the environmental burdens to air from land applied food-based digestate

“…Rigid compliance criteria for Class I digestate have been set by the European 24 Commission (EC) and the British Standard Institution (BSI) (BSI, 2010;EC, 2014). Although the scale of 25 AD operation dedicated to organic waste treatment is at an all-time high (and on the rise), there is still 26 relatively little published information on the composition and potential environmental behaviour of 27 digestate, particularly from AD plants processing food wastes (Tiwary et al, 2015;Whelan et al, 2010). 28…”

“…From an environmental point of view there is an existing 59 challenge of reducing the gaseous N-losses (NH 3 , NO 2 , N 2 O) from digestate soil application to the fields 60 (Balsari et al, 2007;Misselbrook et al, 2005a;Nyord et al, 2008;Tiwary et al, 2015). This study aims 61 to determine and interpret the seasonal emissions profile to air from digestate slurry applied to urban soil.…”

Simulated Dairy Wastewater Treatment in a Pilot Plant Scale Magneto-Active Hybrid Anaerobic Biofilm Reactor (Ma-Habr)

“…However, the extensive energy requirements and many technological problems due to the high organic load and variable quality of wastewater indicate the need to use different methods to reduce the treatment costs and intensify the wastewater treatment efficiency. Anaerobic digestion (AD) has been successfully applied in fullscale for the treatment of dairy wastewater (Tiwary et al, 2015). Several bioreactor types have been used; however, granule and biofilm-based reactors are the most common reactor configurations employed (Karadag et al, 2015;Rajagopal et al, 2013).…”