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.

Another Way of Saying Enough: Environmental Concern and Popular Mobilization in Kyrgyzstan

This article is a foray into the understudied issue of environmental protest politics in Central Asia. Specifically, it uses Kyrgyzstan as a case study to test the argument that environmental concerns mobilized people to engage in protest and in ways different from other kinds of protest. This essay presents the first systematic study of public opinion about the environment in Kyrgyzstan. It includes results from a 2009 nationwide survey, over 100 expert and elite interviews, and newspaper content analysis. Furthermore, it spatially analyzes these results to identify geographical variation in public perception and political event occurrence patterns. Protest engagement is a complex process determined by the interaction of several factors, and is not explained solely by affluence, rationality, or grievances. Eco-mobilization - collective political action about the environment - represents a class of protest events that offers a different view into mass discontent in the former Soviet Union and neo-patrimonial societies. The study finds that these political actions about the environment are not necessarily elite driven; there is a basic foundation of national concern and salience of these issues, and demonstrated environmental beliefs do help to explain protest behavior.