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Properties, agronomic uses and public perceptions of faecal sludge biochar / Larissa Nicholas

Swansea University Author: Larissa Nicholas

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DOI (Published version): 10.23889/SUThesis.65510

Abstract

Since 2000 the proportion of the population in low and middle- income nations that use “unimproved” sanitation facilities is increasing, in 2020 3.5 billion people lacked access to safely managed sanitation facilities. Inadequate sanitation facilities and lack of clean water are key factors in the c...

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Published: Swansea, Wales, UK 2023
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Mabbett, I; Devine, A; Tang, K
URI: https://cronfa.swan.ac.uk/Record/cronfa65510
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Abstract: Since 2000 the proportion of the population in low and middle- income nations that use “unimproved” sanitation facilities is increasing, in 2020 3.5 billion people lacked access to safely managed sanitation facilities. Inadequate sanitation facilities and lack of clean water are key factors in the contraction of diarrheal disease which is responsible for the deaths of approximately 525,000 children every year (WHO, 2017).Faecal sludge collected from on-site sanitation facilities is often dumped into the local environment or reused untreated on farmland. The recycling and re-use of faecal sludge can improve sanitation in developing nations as well as playing a pivotal role in the development of a circular economy within the agriculture industry. Here, biochars derived from faecal sludge were characterized with regards to a potential end-use in agriculture. All faecal sludge biochars were found to have high ash content which contributed to the high pH values measured. All biochars recorded relatively low carbon content and BET porosimetry indicated low specific surface areas. Fourier transform infrared spectroscopy revealed similar organic surface groups for each biochar. X-ray diffraction analysis differed slightly between biochars, but all displayed a high mineral content (Si, Ca, K and Mg).Faecal sludge biochar was investigated as a soil amendment/fertilizer with acidic soil in two experiments; one conducted in an outdoor greenhouse in natural sunlight and one in a controlled temperature laboratory under a 24-hour photoperiod. It was found that faecal sludge biochar addition to acidic soil increased crop yield, fruit number, plant height and plant biomass and also reduced water runoff in Micro-Tom tomatoes. A combined biochar and fertilizer treatment together produced plants with greater plant height, and tomato yield. The high pH biochar initiated a liming effect which increased nutrient availability as evident in the combined biochar and fertilizer treatment. Under continuous light conditions biochar addition increased plant height, and tomato yield compared to control. However, biochar addition resulted in greater continuous light-induced leaf injury compared to the combined biochar and fertilizer treatment. The combined fertilizer and biochar treatment with a lower rate of biochar plus the addition of nutrients significantly reduced continuous light-induced leaf injury.A survey investigating the public perception of biochar as a soil enhancer in agriculture focusing on faecal sludge derived biochar was conducted. This revealed the “disgust effect” – a “squeamishness” associated with the use of faecal sludge biochar by members of the public. Also, gender differences, issue awareness, and age need to be taken into consideration when enforcing management and policy decisions regarding the land application of faecal sludge biochar.
Item Description: Part of this thesis has been redacted to protect personal information
Keywords: Biochar, faecal sludge, soil, crop, yield, tomato, continuous light, public perceptions, attitudes
College: Faculty of Science and Engineering