Urban Waste Management and Potential Agricultural Use in South American Developing Countries: A Case Study of Chimborazo Region (Ecuador)

In South America, a high percentage of urban waste streams are not well managed, implying associated health and environmental risks. In Ecuador, around 2.7 million tons of municipal solid wastes (MSW) are generated annually, with 80 percent located in urban areas. Correct management and hygienic and ecological issues from these increased quantities of waste is the responsibility of municipalities that must provide sewerage, wastewater treatment, and solid waste management, according to the Constitution of the Republic (Art 264). With only seven licensed landfill areas out of thirty-one in total (66 percent mechanized and 34 percent manually sorted), a sustainable waste management model must be developed to reduce environmental hazards and also to obtain new bioproducts such as compost or fertilizers. Agricultural utilization of MSW compost is the most cost-effective management option compared to traditional means such as landfilling or incineration, and this option also enables the recycling of potential plant nutrients. In this work, the problem we addressed was to obtain analytical information about representative MSW samples from different origins and locations within the Chimborazo region in order to establish its potential for composting. In the studied MSW samples (which included sludge from aerobic wastewater treatment plants), high nutrient contents and low concentrations of heavy metals were observed, showing great potential to develop high-quality compost. In addition, improvement of separate collections of food market and/or municipal gardening wastes can provide specific clean waste streams of degradable materials to be managed separately from not separately collected MSW.     

Opportunities and Challenges of Organic Waste Management from the Agroindustrial Sector in South America: Chimborazo Province Case Study

The increase of the agroindustrial sector in South America gives the opportunity to apply the most effective strategies for the disposal and treatment of generated organic wastes. Therefore, it is important to identify the variability in the composition of the agroindustrial wastes to carry out their adequate management. The Ecuadorian province of Chimborazo is located in the central area of the inter-Andean corridor. The main agroindustries in this province are related to the production of vegetables, meat, ornamental plants, flour from different cereals and wood. The management of the wastes from these agroindustries is not optimized with respect to the associated environmental consequences. Therefore, the aim of this work was to carry out a characterization of the different organic wastes from agroindustry to evaluate their potential use as soil amendments. Twenty-seven samples of different types of agroindustrial wastes from the vegetable and animal food-processing industry, wood industry, and ornamental plant production were evaluated for pH, electrical conductivity, water-soluble anions, organic matter, total organic carbon (Corg), total nitrogen (Nt), C/N ratio, water-soluble carbon (Cw), water-soluble polyphenols, macro- and micronutrients, potentially toxic elements, and germination index (GI). The results showed that, in general, the agroindustrial residues were characterized by acidic pH, low EC values, and high organic-matter contents. The macro- and micronutrients and heavy-metal concentrations were greater in the animal agroindustrial wastes than in those from vegetable sources. Most of the materials showed high C/N ratio, low GI values, and high Cw contents, which indicated a lack of organic-matter stability, due to the high content of easily degradable and phytotoxic compounds.