Influence of bulking agent on sewage sludge composting process

Area of Science:

• Environmental Science
• Soil Science
• Waste Management

Background:

• Composting is a sustainable method for organic waste management.
• Acacia dealbata and sewage sludge are common organic materials requiring effective disposal strategies.
• Co-composting offers a potential solution for nutrient recycling and waste reduction.

Purpose of the Study:

• To investigate the effects of different Acacia dealbata (A) to sewage sludge (SS) ratios on the composting process.
• To monitor key parameters including temperature, organic matter, pH, and gas exchange during co-composting.
• To determine the optimal SS ratio for effective co-composting with A.

Main Methods:

• Four compost mixtures of A and SS were prepared at varying ratios (1/0, 1/1, 1/2, 1/3 w/w).
• Composting was conducted in a laboratory reactor for 80 days.
• Parameters monitored included temperature, organic matter, pH, CO2, O2, Kjeldahl-N, C/N ratio, and maturity indexes.

Main Results:

• The A/SS 1/2 mixture achieved the highest temperature (67°C), while A/SS 1/0 reached only 46°C.
• Increasing SS ratio influenced composting parameters, with higher ratios showing increased enzyme-substrate affinity.
• Moderate SS inclusion (1/1 ratio) presented a balance in process factors.

Conclusions:

• The ratio of sewage sludge significantly impacts the co-composting process dynamics and outcomes.
• A moderate amount of sewage sludge (1/1 ratio) in co-composting with Acacia dealbata is recommended for optimal results.
• Further research into enzyme kinetics and process optimization is warranted.