High Solids Co-Digestion of Food and Landscape Waste and the Potential for Ammonia Toxicity

A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15g COD/L-day). At low loadings, methane yields were 232L CH4/kg COD fed and 229L CH4/kg VS fed, and at high loadings yields were 211L CH4/kg COD fed and 272L CH4/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15g COD/L-day. Copyright 2014 Elsevier Ltd. All rights reserved.

The Economics and Nutritional Impacts of Food Assistance Policies and Programs

Recent evidence on malnutrition and poverty raise important questions on the role of food assistance policies and programs. In this review article, we examine evidence on the economic and nutritional impacts of international food assistance programs (FAPs) and policies. The returns on investments in FAPs are, on average, high but depend considerably on the targeting and cost structures as well as on food quality and role of complementary activities. We disaggregate findings into four classes of recipients. Returns to FAPs are highest for children under two. But, FAPs oriented towards early childhood interventions are less well funded than are interventions aimed at school-age children or at the broader, largely adult population even though available evidence indicates that these latter classes of interventions offer considerably lower average returns in economic, health, and nutrition terms. Nonetheless, FAP effectiveness in achieving any of several objectives varies with a range of key factors, including targeting, additionality, seasonality, timeliness, incentive effects, social acceptability and political economy considerations. (C) 2013 Elsevier Ltd. All rights reserved.