The study of composting sludge from supper-intensive shrimp farming ponds to make organic fertilizer for the cultivation of Lactuca Sativa

Abstract

Aquaculture, especially shrimp farming, is bringing significant economic benefits to coastal residents in the Mekong Delta region in general and Ben Tre province in particular. Alongside the benefits, the shrimp farming industry is also discharging a massive amount of waste, including wastewater and sludge after each farming cycle, which is significantly impacting the environment. This study employed the aerobic composting method to decompose organic matter using a combination of shrimp pond sludge and coconut coir pith as the composting materials. The research results showed that after 65 days of composting, the total nitrogen content reached 7.51 g/kg; TOC content reached 10.9%; organic matter content was 18.8%; phosphorus content was 1030 mg/kg; available potassium reached 7.2 g/kg; with a pH of 8.19. The C/N ratio after composting was 19.7, which is very suitable for plant growth. Additionally, the obtained organic fertilizer was used to grow Lactuca Sativa to evaluate the fertilizer's effectiveness in improving soil nutrients. Monitoring the growth results of lettuce showed that the organic fertilizer positively influenced plant growth, but attention must be paid to the fertilization rate due to the high salinity in the fertilizer (EC = 12 mS/cm). With a simple process and low investment costs, the method of treating pond sludge through aerobic composting would bring environmental benefits and save fertilizer costs for the farming community.