Treated swine water as amendment for coffee ground composting system

The rise in demand for coffee and pork has led to an increase in spent coffee grounds (SCG) and swine wastewater (SW) by-products. Commercial fertilizers, which harm the environment, need eco-friendly alternatives like compost. However, little research has focused on combining SCG and SW for composting. This study aims to characterize both SCG and SW and determine the optimal ratio for composting them, as well as their effectiveness when mixed with soil. Additionally, it examines the impact of using SW as a nutrient additive in SCG for organic fertilizer. SCG and SW were collected from local sources and characterized. Using the Berkeley Method, composting was conducted in a 1-meter-high and 0.6-meter-diameter cylindrical pile with a PVC net fence. After the mesophilic phase, the compost was mixed with organic soil and used to grow Bok Choy (Brassica rapa Chinensis) to assess its effects. Results showed that the CS 2 mixture (SCG, SW, and vegetable waste) provided optimal NPK nutrient concentrations and improved soil infiltration and porosity. However, further research is needed to confirm its impact on plant growth. In summary, combining SCG and SW offers a promising solution for reducing waste and commercial fertilizer use, supporting sustainable development goals. © The Authors, published by EDP Sciences.