What is "informal" in informal waste management? Insights from the case of waste collection in the Tepito neighbourhood, Mexico City

This paper explores the meaning of the concept of informality as applied to the waste management sector, by presenting the case of municipal waste collection in a neighbourhood of Mexico City called Tepito. Tepito's municipal service of waste collection is intricately related to informal activities of waste collection and management. This paper focuses on the work of informal street sweepers, who collect waste in certain streets of the neighbourhood, replacing the municipal collection service; and on that of "volunteers", unwaged informal workers recruited by the garbage-men to help on the municipal collection route. The informal cash flows resulting from the work of the volunteers are also described. The case of Tepito illustrates two formal-informal arrangements in the provision of the waste collection service: the coordination of independent services, and a relation of interdependence where the formal system is sustained by informal work. By exploring the scale of informality, the actors involved, and its governance system, this paper suggests that informality exists not as a particular sector of waste management, but rather as unregulated practices carried out by governmental and non-governmental actors, which are enabled by an informal governance system, and which (in Tepito) play a crucial role in sustaining the municipal waste collection service. As different systems of service provision are co-constructed by both formal and informal elements, informality may best be identified at the level of practices that occur within such systems. Conclusions discuss policy implications and avenues for future research.

Parameter interrelationships in a dual phase GIS-based municipal solid waste collection model

Geographic information systems are a valuable tool for waste collection and optimization, but they have been underutilized in helping to understand the complex interrelationships that exist within a dual phase solid waste collection system. A GIS-based dual phase model integrating the handcart pre-collection phase and truck collection phase for a study area located in Hai Phong, Vietnam was proposed, and a resulting total system cost was estimated. Temporary collection points were first identified using both the maximize coverage and minimize facility location-allocation tools from a list of candidate temporary collection points and constraints. Two vehicle routing problems were then separately modeled for handcart and truck routes. A total of 30 scenarios were considered in order to investigate the interrelationships between the model parameters, with respect to the total operation costs and maintenance system costs. The scenario with 11 temporary collection points and a maximum handcart collection distance of 500 m gave the lowest overall cost in the study area. The results suggest a single temporary collection point in the study is able to serve about 2,590 people in an area of 0.11 km². Compared to the status quo condition, a 13.76% reduction in truck travel distances is attainable using the proposed model. It is found that the number and distribution of temporary collection points greatly affected the cost effectiveness in both pre-collection and collection phases.

Greenhouse gas contribution of municipal solid waste collection: A case study in the city of Istanbul, Turkey

This article estimates greenhouse gas emissions and global warming factors resulting from collection of municipal solid waste to the transfer stations or landfills in Istanbul for the year of 2015. The aim of this study is to quantify and compare diesel fuel consumption and estimate the greenhouse gas emissions and global warming factors associated with municipal solid waste collection of the 39 districts of Istanbul. Each district's greenhouse gas emissions resulting from the provision and combustion of diesel fuel was estimated by considering the number of collection trips and distances to municipal solid waste facilities. The estimated greenhouse gases and global warming factors for the districts varied from 61.2 to 2759.1 t CO₂-eq and from 4.60 to 15.20 kg CO₂-eq t^-1, respectively. The total greenhouse gas emission was estimated as 46.4E3 t CO₂-eq. Lastly, the collection data from the districts was used to parameterise a collection model that can be used to estimate fuel consumption associated with municipal solid waste collection. This mechanistic model can then be used to predict future fuel consumption and greenhouse gas emissions associated with municipal solid waste collection based on projected population, waste generation, and distance to transfer stations and landfills. The greenhouse gas emissions can be reduced by decreasing the trip numbers and trip distances, building more transfer stations around the city, and making sure that the collection trucks are full in each trip.

Modeling municipal solid waste collection: A generalized vehicle routing model with multiple transfer stations, gather sites and inhomogeneous vehicles in time windows

Municipal Solid Waste (MSW) collection is a necessary process in any municipality resulting in the quality-of-life, economic aspects and urban structuralization. The intrinsic nature of MSW collection relates to the development of effective vehicle routing models that optimize the total traveling distances of vehicles, the environmental emission and the investment costs. In this article, we propose a generalized vehicle routing model including multiple transfer stations, gather sites and inhomogeneous vehicles in time windows for MSW collection. It takes into account traveling in one-way routes, the number of vehicles per m(2) and waiting time at traffic stops for reduction of operational time. The proposed model could be used for scenarios having similar node structures and vehicles' characteristics. A case study at Danang city, Vietnam is given to illustrate the applicability of this model. The experimental results have clearly shown that the new model reduces both total traveling distances and operational hours of vehicles in comparison with those of practical scenarios. Optimal routes of vehicles on streets and markets at Danang are given. Those results are significant to practitioners and local policy makers.