Abstract
The City Council of Maputo (CMM) and the Japan International Cooperation Agency (JICA) began a pilot project to introduce segregated waste discharge in households and its collection in a suburb of Maputo City, Mozambique, in 2014. After an initial rollout of the program showed low household-level compliance with the new waste segregation requirements, CMM and JICA conducted a randomized control trial (RCT) to evaluate potential measures to induce more cooperation from households. The study was a parallel group comparison with three interventions (i.e., household goods exchange, segregation buckets provision, and periodic home visit instruction). In total, 1000 target households (sample size of 250 households for each group) were randomly allocated out of 1817 eligible households in the target area. The analysis found each applied intervention to be effective, the households with interventions were 7.5–10.6% points more likely to segregate the waste compared with the control group (significant at 1% level), and 267.4–386.1 g/households/2 weeks of target recyclables was incrementally discharged from the intervention groups, while that of the control group was 25.57 g/household/2 weeks (significant at 1–10% levels). However, cost-effectiveness of the pilot project and the applied interventions was low when compared with the other recycling pilot projects attempted in the project.
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Notes
While measuring the causal impact of intervention requires the comparison of outcome levels obtained from “factual” (situation where intervention is performed) and “counterfactual” (situation where intervention is not performed), the latter is never observed. Randomized controlled trial (RCT) is an experimental method that enables to estimate the impact brought about by the intervention, by randomly allocating potential subjects of intervention into two conditions, resulting in having two statistically identical groups except intervention status.
In high-income countries, the effectiveness of related interventions is proved, such as doorstep canvassing to promote recycling in UK [7].
Segregated waste collection requires a certain level of operation capacity. Therefore, the findings from the intervention study can be generalized only to suburban areas with well-performing MEs.
Though the household list obtained from the original census was verified in June 2014, some duplicated households were detected in the subsequent study stages.
Equivalent to US$0.0853 with exchange rate of 0.0322 US$/MZN in June 2014. Household had chance to get 16–18 stamps per month (collection service was provided 2 times per week). Since average monthly expenditure of the households in Maputo City in 2014/2015 was 25,912 MZN [9], it seems to be a small material incentive. Recent evidence from behavioral economics, however, suggests that such microincentive can induce the intended behavioral change [10].
Household waste discharged in the suburb usually contains sand as housing lots in the suburb is mostly unpaved or uncovered. The proportion of sand reached about 35% of discharged waste in the survey, and it was the main reason of high waste discharge rate.
Assuming non-scale economy in household consumption, power calculation based on daily waste per head was rational even if our outcome indicator on the amount of the target recyclables was collected on household basis over 2 weeks.
In allocation process, the surveyors only explained about the pilot project and asked cooperation for receiving the weight measurement and the interview survey.
This positive impact of segregation buckets provision intervention was consistent with the results of Alberto Chong et al. [6].
The buckets was expected to be gradually damaged and exchanged every year. Still, we estimated the buckets provision would cost less than the other interventions as it is 1 time per year intervention. The other interventions were continuous ones and would require labor cost (supervisors following push carts and provide stamps for household goods exchange, instructors for periodic house visit) as well as transportation cost and so on, which resulted in high intervention costs.
It should be noted that the cost of conventional solid waste treatment in Maputo City is increasing year by year, and this cost-effectiveness analysis does not consider an external cost of environmental degradation caused by the conventional treatment.
Another possible interpretation may be negative spillover effect caused by the study design. This study employed a single-level randomization, which might allow the target households to recognize other interventions since households assigned to different groups were scattered around them. If the households in control group were dissatisfied with not receiving any intervention, they might had lost their intention to cooperate on segregation, resulting in decreased amount of the discharged recyclable at the end-line data collection period. On the other hand, it was also possible to allow positive spillover effect to control group. The households in control group might feel peer pressure from neighbors, and without this positive spillover effect, the performance in control group might have been worse than it actually was.
It is worth noting that the study does not reveal anything about the trajectory of outcomes after the end-line data collection. The effects of segregation buckets provision might be less sustainable than household goods exchange and periodic home visit instruction since it was a one-shot intervention.
References
Instituto Nacional de Estatística (2010) Projecções anuais da população total, urbana e rural, dos distritos da Cidade de Maputo 2007–2040. Instituto Nacional de Estatística, Maputo
International Monetary Fund (2014) World economic outlook database. https://www.imf.org/external/pubs/ft/weo/2014/02/weodata/index.aspx. Accessed 22 July 2016
Directorate for Waste Management and Cemeteries, City Council of Maputo City (2017) (Draft) master plan on urban solid waste management in Maputo City. The City Council of Maputo City
Japan International Cooperation Agency (2015) JICA strategy paper on solid waste management. Japan International Cooperation Agency, Tokyo
Website of international initiative for impact evaluation (3ie). http://www.3ieimpact.org/en/. Accessed 22 July 2016
Chong Alberto et al (2015) (Ineffective) messages to encourage recycling: evidence from a randomized evaluation in Peru. World Bank Econ Rev 29(1):180–206
Cotterill S et al (2009) Mobilizing citizen effort to enhance environmental outcomes: a randomized controlled trial of a door-to-door recycling campaign. J Environ Manag 91(2):403–410
Timlett RE et al (2008) Public participation and recycling performance in England: a comparison of tools for behaviour change. Resour Conserv Recycl 52(2008):622–634
Instituto Nacional de Estatística (2015) Relatório final do inquérito ao orçamento familiar—IOF 2014/15. Instituto Nacional de Estatística, Maputo
Datta Saugato et al (2014) Behavioral design: a new approach to development policy. Rev Income Wealth 60(1):7–35
Nippon Koei Co., Ltd. (2013) The project for promotion of sustainable 3R activities in Maputo—progress report 1. Japan International Cooperation Agency, Tokyo
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This study was funded by Japan International Cooperation Agency.
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Supplementary material 2 Tchovas (pushcart) used for primary waste collection equipped with waste segregation bins (JPEG 4215 kb)
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Hosono, T., Aoyagi, K. Effectiveness of interventions to induce waste segregation by households: evidence from a randomized controlled trial in Mozambique. J Mater Cycles Waste Manag 20, 1143–1153 (2018). https://doi.org/10.1007/s10163-017-0677-2
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DOI: https://doi.org/10.1007/s10163-017-0677-2