Assessment of physical and chemical characteristics of bio-organic compost from seafood sludge

Abstract

Seafood sludge (SS) was one of the solid wastes generated during the wastewater treatment processes of seafood processing factories, and it increasingly discharged to the environment. This study aimed to reuse sludge from seafood wastewater treatment plants for producing microbial-organic fertilizer to handle environmental pollution. SS samples were collected at seafood factories in Dong Thap province. Other materials, including sugarcane filter cake (SC) and bagasse (B) were collected in Hau Giang province. Five treatments with three replications for each consisted of a mixture ratio of SS, SC and B at (1) 10-60-30, respectively; (2) 10 + 70 + 20; (3) 20 + 60 + 20; (4) 10 + 70 + 20 and (5) 20 + 80 + 0. All composting mixtures were analyzed for temperature, moisture content, pH, electrical conductivity, volume reduction, organic carbon (OC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) at stages of 0 and 49 days after incubation. Results after 49 incubation days showed that the pH value of both kinds of sludge was slightly acid to neutral (6-7). Electrical conductivity values were suitable from 0.74 to 1.57 mS/cm. The weight loss of incubated samples was 35.87-77.56% after a 49-day incubation. Organic carbon contents were at a high level (over 30% C). After 49 incubation days, the TN, TP, and TK content were high at 2.01-3.03%N; 6.71-9.95%P2O5; and 2.62-3.15%K2O, respectively. The C/N ratio ranged from 12.15 to 19.1. The optimal ratio was mixed with 20% seafood sludge and 80% sugarcane filter cake. The period of 49 days was seen as the suitable incubation time for composting maturity and stability.