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Cycle 6 (2017 Deadline)

Promoting resource- oriented sanitation in peri-urban Ethiopia through the production of struvite from digested sludge filtrate

PI: Adey Desta,, Addis Ababa University
U.S. Partner: Nancy Love, University of Michigan
Project dates: December 2017 - November 2020

Project Overview:

Ethiopia has become one of the fastest growing economies in Africa, with an increasing rate of urbanization and demand for phosphate-based fertilizer to increase productivity in the agriculture sector. Phosphate rock, the starting material for phosphate fertilizer, is a finite resource, and Ethiopia is entirely dependent on importing different kinds of phosphate fertilizers and therefore is vulnerable to market fluctuations in fertilizer prices. The availability and affordability of imported fertilizers to most of the urban and peri-urban farmers is very low because of lack of government subsidies for urban/peri-urban farmers, unlike those provided for rural farmers. The urban/peri-urban farmers get fertilizers at a higher price from local vendors, and the product is difficult to get at any cost at times of shortage.

This scenario suggests the need to look for alternative sources of phosphate to achieve sustainable agriculture. Recovery of phosphorus from digested sludge water has long been a well-established technology in some of the developed countries. Different technologies are available to recover phosphorus from various wastewater streams. Some have been implemented at an industrial scale with maximum recovery efficiency. So far, Ethiopia has not adopted any phosphorus recovery technologies at any level.

This PEER project is aimed at demonstrating that digested wastewater can be used to reliably produce good quality, safe, and marketable struvite fertilizer using full-scale systems. The focus of the study will be on preferred approaches for recovery of phosphorus and nitrogen from digested wastewater with the minimum prevalence of various types of contaminants, such as micropollutants (drugs and metabolites) and biological contaminants (microorganisms and antibiotic resistance genes).

6-400 Desta
 Photo courtesy of Dr. Desta
The information generated about the prevalence and persistence of the pollutants will be useful in further risk assessment studies to predict the risks associated with wastewater reuse. The lab facilities accessible through collaboration with the U.S. partner will be useful for the initial survey of these contaminants from the fertilizer product (struvite) and its raw material, and the information generated will leverage subsequent in-house monitoring studies.

The project will also demonstrate the impact of struvite on commonly grown vegetables, such as carrot and Ethiopian kale, as compared with synthetic fertilizer, which has further implications for addressing issues of food insecurity in the urban areas.

The researcher team plans to work in close collaboration with smallholder farmers of urban and peri-urban areas to understand problems of productivity, the perception of struvite by farmers, and impact of struvite application in the productivity of urban agriculture. Through this approach, the particular needs and challenges of women farmers will also be addressed.

Summary of Recent Activities

During this reporting period,  the PI and her team worked on the design and production of a fluidized-bed reactor and test all of the physical and chemical parameters that determine the optimal recovery of Nitrogen and phosphorus. The bench-scale reactor has been designed and produced. The test has been going on to optimize the various process parameters for the fluidized bed reactor.

In the next 3-6 months the PEER team will work in the actual wastewater based on the optimized process parameters for the fluidized bed reactor. They will also produce a scaled-up pilot scale fluidized bed reactor and check the safety of the produced struvite for its biological and chemical contents

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