Table 4. The economic evaluation of different strategies for the recovery of the imbalanced AD reactor.
| Items | Dilution with tap water (TW) | Dilution with biogas effluent (BE) | NaOH addition | Ca(OH)2 addition | NaHCO3 addition | Oil palm ash addition |
|---|---|---|---|---|---|---|
| Chemical addition cost (USD/m3/d) | −0.02 | 0.00 | −0.49 | −0.19 | −1.73 | 0.00 |
| Human resource cost (USD/m3/d) | −0.05 | −0.05 | −0.15 | −0.15 | −0.15 | −0.15 |
| Energy consumption (USD/m3/d) | −0.10 | −0.10 | −0.02 | −0.02 | −0.02 | −0.02 |
| Biogas loss (USD/m3/d) | −4.26 | −3.46 | −3.20 | −3.73 | −5.30 | −3.46 |
| Biogas production (USD/m3/d) | 1.04 | 1.84 | 2.10 | 1.60 | 0.00 | 1.84 |
| Net profit (USD/m3/d) | −3.39 | −1.77 | −1.76 | −2.49 | −7.20 | −1.79 |