Overview
Gumilar and colleagues tested whether nickel and molybdenum additions changed ethanol formation during anaerobic treatment of palm oil mill effluent. This is in-scope supply-chain wastewater-treatment and trace-metal-addition context: it reports POME metal concentrations and metal dosing in a treatment process, but it is not palm-oil occurrence evidence and it does not report heavy-metal removal.
Key numbers
Table 2 reports the starting palm oil mill effluent characteristics. All units are mg/L except pH:
| Parameter | Value |
|---|---|
| Total COD | 30367 |
| BOD | 14500 |
| Soluble COD | 18433 |
| pH | 4,3 |
| Oil and grease | 630 |
| Ammonia (NH3) | 26,77 |
| Nitrogen total | 265,67 |
| Total suspended solids (TSS) | 6200 |
| Volatile suspended solids (VSS) | 3967 |
| Ethanol | 44,4 |
| Volatile fatty acids (VFA’s) | 566,67 |
| Iron (Fe) | 14,96 |
| Manganese (Mn) | 2,09 |
| Molybdenum (Mo) | < 0,001 |
| Nickel (Ni) | 0,025 |
| Copper (Cu) | 0,073 |
| Zinc (Zn) | 0,051 |
Table 1 defines the nine reactor conditions:
| Run/reactor | Ni added (mg/L) | Mo added (mg/L) |
|---|---|---|
| Control | 0 | 0 |
| Reactor A | 0 | 1 |
| Reactor B | 0 | 3 |
| Reactor C | 0.25 | 0 |
| Reactor D | 0.25 | 1 |
| Reactor E | 0.25 | 3 |
| Reactor F | 0.5 | 0 |
| Reactor G | 0.5 | 1 |
| Reactor H | 0.5 | 3 |
The abstract reports that reactor E, with Mo 3 mg/L and nickel (Ni) 0.25 mg/L, produced the highest ethanol concentration at 578.44 mgCOD/L. The highest COD removal occurred in reactor D, with Mo 1 mg/L and Ni 0.25 mg/L, at 23.4%.
Table 6 reports anaerobic products after treatment:
| Reactor | Ethanol (mgCOD/L) | Acetate (mgCOD/L) | Propionate (mgCOD/L) | Butyrate (mgCOD/L) | Valerate (mgCOD/L) | VSS (mg/L) | COD aq (mg/L) | pH |
|---|---|---|---|---|---|---|---|---|
| Control | 320.52 | 3815.73 | 844.81 | 2305.08 | 291.66 | 4296 | 16520 | 4.79 |
| A | 416.78 | 4315.81 | 1056.53 | 2073.49 | 251.66 | 4222 | 14368 | 5.13 |
| B | 399.39 | 4118.81 | 962.12 | 2319.98 | 231.83 | 4192 | 14886 | 5.66 |
| C | 480.11 | 4961.03 | 878.25 | 2078.94 | 382.51 | 4371 | 14953 | 4.98 |
| D | 510.21 | 4228.45 | 1056.62 | 2202.60 | 248.33 | 4491 | 14119 | 5.19 |
| E | 578.44 | 4199.52 | 1037.44 | 2168.87 | 283.61 | 4264 | 14368 | 5.28 |
| F | 511.24 | 3819.33 | 886.73 | 2274.72 | 272.62 | 4517 | 15027 | 5.21 |
| G | 521.68 | 4972.57 | 916.28 | 1954.31 | 318.5 | 4291 | 14892 | 4.89 |
| H | 520.88 | 4281.65 | 821.73 | 2175.13 | 300.25 | 4028 | 15120 | 5.36 |
The authors report that the ANOVA significance value for ethanol production was 0.000, interpreted as a significant difference among reactor conditions. They state that the highest degree of ethanofication was 0.031 in reactor E, while other reactors ranged from 0.017 to 0.028. Degree of acidification ranged from 0.394 to 0.450, with the smallest value in the control reactor.
Methods (brief)
The study used laboratory-scale anaerobic batch reactors with 5 L working volume. Palm oil mill effluent was collected from PT Condong Garut, Indonesia. Biomass was sludge of POME mixed with cow rumen at 50:50 (v/v) and acclimated to the wastewater. Reactors were flushed with nitrogen at 1 L/min for the first 24 h and then operated with internal biogas circulation until 72 h at 25 +/- 2 degrees C. Initial pH was adjusted to 6.5-7.0, and reactors were filled with POME and biomass at 4:1 (v/v). Nickel was added as NiSO4.6H2O and molybdenum as (NH4)6Mo7O24.4H2O. Soluble COD, pH, and VSS followed Standard Methods; volatile fatty acids were measured by HPLC; ethanol was measured by GC.
Related evidence
- Irrigation water and soil amendments as anthropogenic inputs to cropland
- Source attribution and environmental burden apportionment
- Nickel
- Molybdenum
- Copper
- Zinc
- Iron
- Manganese
Update history
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