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The implementation of waste selective collection (SC) schemes in low-income countries is a challenge although it is one important way for improving environmental sustainability. The inclusion of the population is necessary for gaining effective results, and social surveys are support methods for understanding citizens' involvement and behaviour. The aim of the research is to assess the support of the citizens concerning the formal and informal recycling in a low-middle income country. The study presents a questionnaire survey conducted in 2018 in La Paz, Bolivia, where 774 citizens were interviewed for evaluating their support to the formal and informal SC systems. Two questionnaires were submitted to two different users' categories: users of the formal recyclable waste gathering points; and citizens of the neighbourhoods. Evidence of the survey shows that about 8% of the population supports the formal SC while about 48% are used to selecting their waste at home. About 79.2% of them bring the waste to the informal recycling shops or provide it to waste pickers, throwing the waste into or nearby the mixed containers in order to facilitate their collection. This research demonstrates how social inclusion is important for planning recycling systems within a developing big city, starting from the SC. Results suggest that the informal sector can be an effective means for improving the recycling behaviour of the citizens. The study can be of interest to stakeholders involved in introducing recycling policies in developing cities where the SC rate is still low, and informal waste collection exists.

Among the critical issues that prevent the reuse of wastewater treatment plants (WWTPs) effluents in a circular economy perspective, the microbiological component plays a key role causing infections and diseases. To date, the use of conventional chemical oxidants (e.g., chlorine) represent the main applied process for wastewater (WW) disinfection following a series of operational advantages. However, toxicity linked to the production of highly dangerous disinfection by-products (DBPs) has been widely demonstrated. Therefore, in recent years, there is an increasing attention to implement sustainable processes, which can simultaneously guarantee the microbiological quality of the WWs treated and the protection of both humans and the environment. This review focuses on treatments based on ultraviolet radiation (UV) alone or in combination with other processes (sonophotolysis, photocatalysis and photoelectrocatalysis with both natural and artificial light) without the dosage of chemical oxidants. The strengths of these technologies and the most significant critical issues are reported. To date, the use of synthetic waters in laboratory tests despite real waters, the capital and operative costs and the limited, or absent, experience of full-scale plant management (especially for UV-based combined processes) represent the main limits to their application on a larger scale. Although further in-depth studies are required to ensure full applicability of UV-based combined processes in WWTPs for reuse of their purified effluents, excellent prospects are presented thanks to an absent environmental impact in terms of DBPs formation and excellent disinfection yields of microorganisms (in most cases higher than 3-log reduction).

Using a life cycle assessment (LCA) to evaluate municipal solid waste management (MSWM) systems is strongly recommended and the approach has been used in high-income contexts. However, stakeholders in low to middle income countries are not aware of the potential of this approach, mainly due to a lack of financial resources and technical ability. The present work introduces a LCA of MSWM system scenarios into a developing city using an academic licence for the LCA software that is available for use exclusively by researchers. The MSWM system in place in 2018 in La Paz (Bolivia) was assessed according to seven scenarios. The novelty of the research is twofold: the use of LCA academic licensing in a low to middle income region where LCA is unknown as planning tool; and discussing the potential of the approach in conjunction with local and international stakeholders with a view to starting MSWM projects. The results of the analysis allow for the consideration of energy recovery and materials recycling as the main methods by which the environmental impact of MSW can be reduced, as has also been reported by other LCA studies conducted with full licensing of the relevant software. Moreover, the research is the basis for cooperative development projects that will adopt the LCA approach as the main assessment tool. The study discusses the importance of cooperation between universities and local governments for implementing new strategies for MSWM assessment and planning. The research is a contribution towards improving technical knowledge in developing countries for boosting sustainable development.

In the developing world, healthcare waste management is a human health and environmental burden that should be solved for improving sustainability. Solutions should be introduced in the short term, concerning management, planning, financial assistance and expertise. The paper introduces an indicator set for assessing healthcare waste management in developing cities, implemented in La Paz (Bolivia) as a case study. The objective is to suggest an integrated management tool as a first assessment technique to identify the prevailing problems with a healthcare waste management system. Results suggest that, in La Paz, the application of such indicators is useful for evaluating which priorities should be addressed for improving the healthcare waste management system. The tool was applied for introducing a study necessary for the application of new management plans, especially concerning healthcare waste treatment. The method can be replicated in other contexts worldwide, with a focus on the developing world, for comparing cities, management solutions and improvements carried out along the years. The approach is of interest for boosting sustainability and human health, improving the awareness of the actors and policy-makers involved in waste management.

The management of animal slurry is a big issue in low-income rural areas worldwide. Bolivia suffers this issue related to collection, treatment and final disposal since the main solution applied is the open dumping. The aim of this study is to introduce a feasible treatment of animal slurry in the rural area of Carmen Pampa, where about 670 kg of dung are produced per day and disposed of in open areas. The objective is the improvement of the environmental sustainability and human health, providing an alternative solution for encouraging the circular economy. The study is focused on the vermicomposting process, a sustainable solution for low-income regions. The analysis was conducted in function of the earthworm breeds used locally ( Eisenia fetida and Lumbricus terrestris) and the application of activated bacteria (AB) for improving the process. The mass loss, the treatment time, and the growing rate of the earthworms were analyzed. The results suggest that the different breed of the worms allows gaining up to 19 days, while the use of the AB allows saving about 30 days. Moreover, the vermicomposting process reduced the mass of the slurry of about 65% for the swine's dung and the bovine's dung, and 90% of the hens' dung. Finally, experimental evidence shows that the growing rate of the E. fetida is higher than the L. terrestris (F[1,8] = 78, p < 0.05), with an average of about 193%. The data obtained could be of interest for other stakeholders who live in similar environmental, climatic, and economic conditions for improving sustainability.

This paper investigates dynamic variation in the morphologic distribution of dense non-aqueous phase liquids (DNAPLs), which take into account the coupled mass transfer. Experiments were carried out in a 2D tank representing a reconstructed aquifer model. DNAPL dissolution rates were investigated over a wide range of DNAPL saturations, several source configurations, and different hydraulic conditions. Morphometric indexes are presented that take into consideration further factors affecting the dissolution process. Local information regarding transport parameters related to the characteristics of the medium was obtained through a neural network and an optimization algorithm applied to experimental tracer tests. The history of DNAPL source architecture, in terms of saturation, indentation grade, and orientation, was determined by image analysis. Dissolved concentrations were registered and mass transfer rate coefficients were obtained for a wide range of source-zone configurations. A statistical analysis was performed to develop a constitutive equation that is descriptive of the mass transfer rate as a function of source-zone metric characteristics. A new empirical dissolution model using the proposed morphometric parameters is presented and compared with other models. The mass transfer correlation reported incorporates morphometric parameters and considers the complex and variable architecture of non-miscible contaminants. The proposed correlation can be used for an initial assessment of non-aqueous phase liquid (NAPL) dissolution rates over a wide range of saturation (residual and non-residual) conditions and different aqueous phase velocities within the NAPL source zone.

Arsenic is among the most dangerous contaminants which can limit groundwater use for drinking water consumption. Among the most diffused As-removal technologies around the world, adsorptive media systems are usually favored for relatively low cost and simplicity of operation. This study examines the performance of a laboratory-scale iron oxide-coated sand (IOCS) column filter, to remove arsenic (arsenate (As[V]) and arsenite (As[III])) from groundwater. This technology could be adopted in small communities, as it showed consistent removal rates of 99% with an easy-to-operate process. Some considerations about the possible introduction of such technology in developing countries are provided, highlighting the general impacts to human health related to high arsenic concentrations in groundwater. This, among other adsorption processes, could be recommended as a sustainable mean of ensuring good drinking water quality in developing regions, reducing human health impacts.