Types of Research
This brief reviews the literature and empirical evidence on waste extraction and treatment in the developing world. The brief assesses the quantity and quality of research supporting key components of program theory related to the extraction of sludge from on-site sanitation facilities and pre-disposal transport. In general, we find few empirical studies that directly evaluate the assertions of the program theory. Most of the evidence in the literature that addresses the target components of program theory is based upon case studies or general observational and experiential assertions by sanitation experts. Where appropriate, we have identified evidence in the literature according to whether case studies or informal observations formed the basis of the conclusion.
The purpose of this literature review is to provide qualitative and quantitative examples of technologies, constraints and incentives for efficient waste treatment and reuse in Sub-Saharan Africa and Southeast Asia. We present relevant case studies and expert observations and experiences on the nutrient content in urine and feces, contaminants frequently found in untreated sludge and wastewater, waste treatment technologies that may be relevant for low-income countries, risks associated with waste reuse, benefits to resource recovery in agriculture. We further discuss reasons for waste treatment failures, including urbanization, observations on challenges with market-driven reuse in less developed countries, and examples of net-positive energy facilities in Europe and the United States. Much of the evidence presented in the literature relates to wastewater treatment processes or the sludge produced from wastewater treatment as opposed to untreated fecal sludge. However, examples of risks, failures, and opportunities for raw sludge treatment and reuse are discussed when available. In some cases, empirical evidence or case studies were not available for developing countries and alternatives are presented. Overall we found the empirical evidence on waste treatment and reuse in developing countries is quite thin.
The purpose of this literature review is to identify the linkages between increases in agricultural productivity and poverty reduction. The relevant literature includes economic theory and evidence from applied growth and multiplier models as well as micro-level studies evaluating the impact of specific productivity increases on local poverty outcomes. We find that cross-country and micro-level empirical studies provide general support for the theories of a positive relationship between growth in agricultural productivity and poverty alleviation, regardless of the measures of productivity and poverty that are used. The evidence also suggests multiple pathways through which increases in agricultural productivity can reduce poverty, including real income changes, employment generation, rural non-farm multiplier effects, and food prices effects. However, we find that barriers to technology adoption, initial asset endowments, and constraints to market access may all inhibit the ability of the poorest to participate in the gains from agricultural productivity growth.