Feasibility and Performance Evaluation of Different Low-Tech Composter Prototypes

Abstract

Abstract-Decentralized composting has become a powerful option for municipal organic waste management. This technology, not only is an effective tool to treat organic waste, producing compost as a valuable by-product, but also represents an innovative way to involve waste generators in treatment operations. Decentralized composting contributes to reducing waste transportation, treatment costs and landfilling volumes thus resulting in a positive impact on municipal waste management programs. In this work, three lowtech composter prototypes were designed and built using discarded metallic oil drums and recycled plastic materials. The composting experience was carried out at an oilfield, using food waste from a catering service for 65 people. Temperature was used as the main indicator of the composting process, and final product quality was characterized through the following variables: total nitrogen, total phosphorous, extractable phosphorous, pH, organic matter and electrical conductivity. Results confirm the effectiveness of this composting technology for organic waste treatment: thermophilic temperatures were reached in all prototypes, and final products obtained from all composters showed high nutrient and organic matter contents, but also high pH and electrical conductivity values, which frequently appear in decentralized composting product; however, obtained values are still adequate for agronomic applications. Nevertheless, some significant differences were found for these variables among the prototypes, possibly related to design characteristics. Finally, composters construction could be optimised by recycling other waste, as shown in this experience (metallic drums, high density polyethylene and accessories), in order to improve the strategies for decentralised composting.

Inside the small-scale composting of kitchen and garden wastes: Thermal performance and stratification effect in vertical compost bins

“…In previous work, as well as in other authors experiences, elevated EC values were observed in compost made from dining wastes. This is associated to the presence of cellulosic material in the feedstock, such as napkins and tablecloths made with paper (Arrigoni et al, 2015;Faverial and Sierra, 2014;Kalamdhad and Kazmi, 2009a;Kalamdhad and Kazmi, 2009b). However, in this study, the differences in the EC values between the upper and the lower layers of the composter, also would show leachates accumulation in the lower part of the composter; leachates frequently include dissolved salts and, thus, increase compost electrical conductivity.…”

“…Since commercial compost bins volume usually range from 40 to 500 L, in these systems the thermal inertia is usually lower because the composting mass could not be enough to retain the metabolic heat generated during the composting active phase. Therefore, small-scale composting systems could have a poor performance in achieving USEPA PFRPs or other temperature sanitization standards or recommendations (Abdullah et al, 2013;Arrigoni et al, 2015;Benjawan et al, 2015;Iyengar and Bhave, 2006;Sánchez et al, 2015). In tropical and favourable climatic conditions or in controlled laboratory settings, small-scale composting has shown good temperature evolution performances (Barrena et al, 2014;Faverial and Sierra, 2014;Lleó et al, 2013;Varma and Kalamdhad, 2014).…”

“…In tropical and favourable climatic conditions or in controlled laboratory settings, small-scale composting has shown good temperature evolution performances (Barrena et al, 2014;Faverial and Sierra, 2014;Lleó et al, 2013;Varma and Kalamdhad, 2014). However, in cold climates, such as the Andean Patagonia region in Argentina, typical low ambient temperatures could maximize heat loss and restrict microbial activity, negatively affecting compost stabilization and sanitization, and also increasing the time required for the process to be completed (Arrigoni et al, 2015;Laos et al, 2002).…”

Composting paper and grass clippings with anaerobically treated palm oil mill effluent

“…In general, a thermophilic process is believed to accelerate composting. However, based on a study by Arrigoni et al (2015), a thermophilic process is not a guarantee for higher Table 2). The lower mass reductions might be due to the presence of lignin, which is relatively more degradable in aerobic environments but refractory in anaerobic ones (Komilis and Ham 2003).…”