Human excreta is a valuable fertilizer for improving soil quality and crop productivity, with a potential to replace or complement the mineral fertilizers. The main challenges related to human excreta regarding agricultural applications are microbial contamination risks, loss of nutrients, and odor issues. Fertilization by lacto-fermented faeces supplemented by biochar has benefits such as improved soil bulk density, nitrate and potassium concentrations as well as the yield and yield components of corn, compared to untreated, simple stored faeces, urine, cattle manure, and unfertilized controls. Even though the mineral fertilizer produced corn with significantly higher height and leaf length, it did not add significantly higher yields than lacto-fermented faeces supplemented by biochar.
A faeces treatment process by combined lacto-fermentation with thermophilic composting and biochar supplementation had better reduction of coliforms, Escherichia coli, Enterococcus faecalis and Clostridium perfringens, and higher germination of radish and growth of tomatoes than combined lacto-fermentation with vermicomposting. Urine lacto-fermentation contributed to a pH reduction below 4, a decrease in the ammonium concentration and odor strength, as well as an increase in the germination rates compared to untreated stored urine.
The results of this study provide important information that can set the basis for scaling up a sustainable technology for the treatment of source separated human excreta while improving its potential for resource recovery.
Chapter 1. General Introduction
1.1 Research justification
1.2 Scope of research
1.3 Thesis outline
Chapter 2. Increasing the agricultural value of human excreta by lactic acid fermentation, composting and biochar addition (literature review)
2.2 Nutrient and resource challenges in sanitation
2.3 Applying excreta and biochar to agriculture
2.4 Challenges in agricultural reuse of excreta
2.5 Lactic acid fermentation of human excreta
2.6 Post treatment of lacto-fermented human excreta
2.7 Agricultural effects of lacto-fermented excreta
Chapter 3. Treatment of source-separated human faeces via lactic acid fermentation combined with thermophilic and vermi-composting for agricultural application
3.2 Materials and Methods
Chapter 4 The effect of lacto-fermented faeces, biowaste and addition of biochar soaked in urine on soil quality, growth, yield and yield components of Zea mays L.
Chapter 5. Lactic acid fermentation of human urine for improving its fertilizing value and reducing odour emissions in urine diverting dry toilets
5.2 Material and methods
Chapter 6. General Discussion and Outlook
6.1 Potential and limitations of the application of lactic acid fermentation and biochar in excreta treatment
6.2 Product quality assurance for potential full-scale application
6.3 Input materials required for lactic acid fermentation of excreta
6.4 Agricultural application of lacto-fermented excreta and biochar
6.5 Application of lactic acid fermentation combined with composting and biochar in urine diverting dry toilets in Moldova
6.6 Potential entrepreneurial models
IHE Delft PhD programme leads to a deepening of a field of specialisation. PhD fellows do scientific research, often with conclusions that directly influence their region. At IHE Delft, PhD researchers from around the world participate in problem-focused and solution-oriented research on development issues, resulting in an inspiring research environment. PhD fellows work together with other researchers from many countries dealing with topics related to water and the environment.
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