Closed-Loop Biodigesters on Small-Scale Farms in Low- and Middle-Income Countries: A Review

Isha Kulkarni,Joachim Werner Zang,Luiza C Campos,Warde A Da Fonseca-Zang,Priti Parikh,Wilson M Leandro,Ilan Adler

doi:10.3390/w13192744

Abstract

Anaerobic digestion (AD) systems are prominent in low- and middle-income countries (LMICs), although their implementation within organic farms to enhance resource efficiency and “close the loop” has been limited. This paper thus reviewed existing literature on the potential of AD technologies as part of closed-loop rural family farming communities in LMICs. Data from eleven existing case studies matching this criterion was then collated to understand practical considerations of implementing and maintaining viable AD systems for small farmers. The case studies analyzed indicate that most, if not all, of the biogas produced in the AD process is used for household purposes such as cooking, lighting and heating. The AD systems are either based on the fixed biogas dome or the floating drum design, although the tubular flexible balloon model is mentioned as a low-cost alternative. Future research opportunities in this topic include studying the applicability of recommendations offered across different geographies, consideration of long-term sustainability and impact of biodigester technology, and sociocultural factors such as community ownership and indigenous practices.

Highlights

Organic agriculture is a method of farming that seeks to produce food with minimal impact to ecosystems, animals or humans [1]
An alternative technology to CFSTR for the farming sector is covered anaerobic lagoons (PVC covers for biogas storage), which are relatively low cost and easy to build, and are used for the treatment of effluents from agriculture, livestock, industry and sanitary sewage treatment
Indirect abatement of carbon dioxide emissions through the use of biogas and avoidance of synthetic fertilizer can form a part of this research. This structured review aimed to assess and recommend closed-loop technologies for small-scale waste–water–energy–food systems focusing in small-scale farms in low- and middle-income countries (LMICs)

Summary

Introduction

Organic agriculture is a method of farming that seeks to produce food with minimal impact to ecosystems, animals or humans [1]. More than a fifth of all organic agricultural land is located in low- and middle-income countries that are recipients of official development assistance (ODA) [7]. This may be attributed to the often-limited access of small-scale farmers in such environments to chemical fertilizers, improved seeds, irrigation water and pesticides, caused by their lack of capital, infrastructure and market access [8]. In such a context, “closing the nutrient cycle”—recycling nutrients and organic matter—is

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