P recovery from nightsoil-treated sludge using chemical and biological methods
1
Issued Date
2023
Copyright Date
2023
Resource Type
Language
eng
File Type
application/pdf
No. of Pages/File Size
xi, 110 leaves : ill.
Access Rights
open access
Rights
ผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้า
Rights Holder(s)
Mahidol University
Bibliographic Citation
Thesis (Ph.D. (Environmental Technology))--Mahidol University, 2023
Suggested Citation
Wanida Pimpeach P recovery from nightsoil-treated sludge using chemical and biological methods. Thesis (Ph.D. (Environmental Technology))--Mahidol University, 2023. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/115310
Title
P recovery from nightsoil-treated sludge using chemical and biological methods
Author(s)
Abstract
The study aimed to comprehensively enhance the techno-economic feasibility of phosphorus (P) recovery from nightsoil-treated sludge (NTS) or primary settled-nightsoil sludge (PSNS) using acid leaching (a chemical process) and anaerobic co-digestion (a biological process). Results obtained from the chemical process showed that 92.7% of P could be effectively extracted from PSNS of 20,000 mg/L with 0.5 M of H2SO4 at a reaction time of 45 min (optimum condition). Moreover, the pseudo second-order was fit to describe the dynamics of the P, Fe, Mg, and Ca leaching processes. Kinetic studies showed that the 99% leaching of the maximum extracted P concentration at equilibrium (9.6673 mg/g) took place in less than 1 h. Regarding P recovery, the highest phosphorus yields (more than 98%) were obtained at pH 11 for all cases. In addition, 15.2% struvite (magnesium ammonium phosphate, MAP) with the highest P content of 9.7% in precipitates could be achieved under pH 9 with sea salt addition. For the biological process, anaerobic co-digestion (AcoD) was inhibited by the accumulation of undigested feedstock due to the higher PSNS found in AD4 (25FW:75PSNS) and AD5 (100PSNS). A more stable process was found in AD2 (75FW:25PSNS) under HRT 15 days, in which COD removal efficiency and P release were 97.2 and 80.2%, respectively. This recommended condition allowed a high organic loading rate (OLR) at 12 gVS/L/d, resulting in the highest biogas yield of 0.93 L/L/d. P recovery efficiency from effluents and %P in solids decreased with increasing total suspended solids (TSS), indicating the adverse effect of TSS on struvite quality. The precipitates formed from AD2 effluents had the highest MAP of 46% with 10.94% of P in solids. The operational costs assessment demonstrated that the chemical method generated a higher average cost of more than 100 USD kg P −1 . However, the AcoD system under AD2 and AD3 had a profit margin of more than 8 USD kg P −1 when the product’s market price was greater than 13.5 USD kg P −1 . Thus, the P recovery process using AcoD of PSNS and FW could be used as a pragmatic way to utilize PSNS as an alternative resource for P.
Degree Name
Doctor of Philosophy
Degree Level
Doctoral degree
Degree Department
Faculty of Public Health
Degree Discipline
Environmental Technology
Degree Grantor(s)
Mahidol University