| Popis: |
Previous studies demonstrated that the solid waste generated in agricultural projects, such as dairy and swine farms in Puerto Rico, is equivalent to the waste generated by six million persons. Anaerobic digestion is a waste treatment technology that can convert wastes into renewable energy and biofertilizer. Capture of the methane gas for use as a fuel would significantly reduce the net greenhouse gas production from dairy farms. The Dairy Farm at the Lajas Agricultural Experimental Sub-Station (AES) was selected for this research. Three field scale anaerobic digesters (plastic containers) systems were built for this study. Feed was prepared once a week by diluting the fresh dairy cow manure with water to obtain 3 different desired organic load ratios (3:1, 4:1 and 5:1). Liquid samples were collected from the feeding tank and effluent outflow. Samples were analyzed for major nutrients, total suspended solids, total volatile solids (TVS), temperature, pH, biological oxygen demand (BOD5), and chemical oxygen demand. Also, the biogas produced was measured and analyzed. The Lajas AES lagoon wastewater has maximum and minimum BOD5 concentrations of 414 mg/L and 100.5 mg/L, respectively, and total suspended solids (TSS) with maximum values of 485 mg/L and minimum values of 75 mg/L. Preliminary results indicated that TSV destruction in the 3:1 ratio digesters was about 8,000 mg/L, compared to a TSV destruction of 1,000 mg/L for the 5:1 ratio. This research focuses on developing guidelines for the conversion of waste treatment ponds of the PR dairy industry into energy reactors that recover carbon in the form of methane gas for power generation. |
