Sustainable Utilization of Sewage Sludge through the Synthesis of Liquid Fertilizer

Yan-Jhang Chen, Li-Pang Wang and Sandhya Babel
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Yan-Jhang Chen: Institute of Environmental Engineering and Management, College of Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
Li-Pang Wang: Institute of Environmental Engineering and Management, College of Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
Sandhya Babel: School of Bio-Chemical Engineering and Technology, Sirindhorn International Institute of Technology, Thammasat University, Pathum Thani 12120, Thailand

Sustainability, 2021, vol. 14, issue 1, 1-14

Abstract: In a world with a growing human population, resources are becoming increasingly scarce. To ensure food supply, fertilizers are often used to accelerate growth when planting agricultural products. Sewage sludge (SS), containing as high as 10–15 wt% Phosphorus (P), can be synthesized into liquid fertilizer. P species in SS can generally be classified into four types: inorganic phosphorus (IP), organic phosphorus (OP), nonapatite inorganic phosphorus (NAIP), and apatite phosphorus (AP). However, OP is not leached out by wet chemical methods and NAIP is not bioavailable. This study investigated the P-form conversion (OP and NAIP to AP) in SS by adding 8 wt% CaO at 300 °C. SS through pretreatment can easily leach out P when combined with organic acid. The content of heavy metals is in accordance with fertilizer regulations in a leaching solution. The solution was mixed with potassium and ammonia compounds to synthesize a liquid fertilizer. To ensure the safe and efficient use of liquid fertilizer and undertake an analysis of heavy metals, an aquatic organisms (D. magna) toxicity test, and the growth of plants test were both used. The liquid fertilizer can be demonstrated to accelerate the growth of plants while not causing the death of D. magna in short time, as the liquid fertilizer has enough nutrients to help the D. magna to survive.

Keywords: sewage sludge; liquid fertilizer; synthesis; conversion; wet chemical method (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
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