Unconventional small-scale biogas production with reduced local impact

Abstract

One of the problems of food waste management is the acceptability of the treatment plants at local level because of the risk of odours. Anaerobic digestion as first step before composting has contributed to solve this problem, but, in the sector, it remains an opposition to large plants. That affects also food waste anaerobic digestion: people's perception is that the stream coming at the gate of the plant is not theirs. The present paper shows an alternative to the conventional approach. The aim is to reduce the scale of the intervention giving a solution also to small municipalities or to an aggregation of small municipalities. The basic idea is suitable for adaptations depending on the local availability of manure and other plants specialised on wastewater. The integrability of these plants allows reducing the costs for treating secondary streams to be managed, as discussed in the article. The extreme technological scenario is based on an anaerobic digester with unconventional pre-treatment of food waste and energy recovery, on a hydro-thermal carbonisation reactor for manure, on an ammonia separator for product recovery (by stripping), on a CO 2 separator (from off-gases), on a hydro-biochar flusher for opening to land application and on mechanised small-scale composters for small communities. The principles of the circular economy are adopted, but the economic balance is affected by the transport costs of the products. The suitability of this approach to medium income countries is discussed too.

From Circular Economy to Circular Ecology: A Review on the Solution of Environmental Problems through Circular Waste Management Approaches

“…In the perspective of reducing the carbon emissions, improving resource efficiency, minimizing waste production and potential damages to soils, another interesting opportunity of CE L approaches consists in the optimization of the different circuits available to valorize zootechnical waste, whose contribution to local air pollution, odors, greenhouse gas emissions, and nitrate contamination of soils and aquifers are known. In this regard, an innovative approach is suggested by a recent paper, consisting in the coupling of the HTC of swine manure with the AD of OFMSW to produce energy, compost, and hydrochar [142]. Both compost and hydrochar could be used locally for agricultural applications, thus closing the cycle of the organic waste in a rural context.…”

How Can Biodigesters Help Drive the Circular Economy? An Analysis Based on the SWOT Matrix and Case Studies

“…Dahlin et al [57] compared the concentration of cadmium (Cd) in wheat grains from land fertilized with biofertilizer and land fertilized in a traditional manner and found that the inappropriate use of chlorine in soils with digested material significantly increased the concentration of Cd in the crop products. For Rada et al [58], food waste management at the local level has the risk of bad smell as a negative factor, but this can be minimized with AD and, if the organic volume is high, additional treatment plants will be needed, raising the cost of the infrastructure needed to build the digesters.…”

“…High transportation costs when the biodigester is far away from the point of waste collection or from the land where the biofertilizer is to be used [35,36,54,58,62] Lack of knowledge about the energy potential of the sector Lack of awareness of the energy potential that can be obtained with the use of biogas [40] Population awareness Lack of knowledge of the population about the advantages of biodigesters and the need for proper separation of waste [40,58] Contamination of soil, air, water, etc.…”

Experimental characterization of biomass–coal fuel mixtures

“…Renewable energy is vital as an alternative source of energy. Due to the continuous rapid depletion of fossil fuels, renewable energy is gaining increasing popularity to supplement and, perhaps in the future, replace the role of fossil fuels [1]- [4]. In this context, an important point is the consideration of the national priorities.…”