Anaerobic Co-Digestion of Tannery and Slaughterhouse Wastewater for Solids Reduction and Resource Recovery: Effect of Sulfate Concentration and Inoculum to Substrate Ratio
Abstract
:Highlights
- Tannery effluent characteristics exhibited significant batch to batch variability
- Inhibition was seemingly caused by , and S, respectively
- The inhibitory effect of led to a significant decrease in A, µm, and K
- Process recovered , , and reusable water e.g for irrigation and construction
- Models perfectly fitted in the order Logistic > Cone > modified Gompertz > first order
1. Introduction
2. Materials and Methods
2.1. Sampling
2.2. Analytical Methods
2.3. Biomethane Potential Experiments
Biogas Sampling and Analysis
3. Results and Discussion
3.1. Characteristics of Ostrich Tannery Effluent
3.1.1. Chemical and Biological Oxygen Demand and Solids Concentrations in the Ostrich Tannery Effluent
3.1.2. Concentration of Nitrogen, Carbon and Volatile Organic Acids in the Ostrich Tannery Effluent
3.1.3. Inorganic Characteristics of Ostrich Tannery Effluents
3.1.4. Metal Characteristics of Ostrich Tannery Wastewater
3.2. Biochemical Methane Potential Experiments
3.2.1. Cumulative Methane Generation
3.2.2. Hydrolysis and pH Changes
3.2.3. Acidogenesis, Acetogenesis and Changes in Volatile Organic Acid Concentration
3.2.4. Sulfidogenesis, Sulfite Oxidation and Methanogenesis
3.2.5. Metal Inhibition or Stimulation and Macronutrient Limitation
3.3. Optimisation of Cumulative Methane Yield and Anaerobic Biodegradability
3.3.1. Water Reuse
3.3.2. Correlative Analysis of Variables on Methane Yield and Anaerobic Biodegradability
3.4. Kinetic Study of Cumulative Methane Production
3.5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
A | ultimate methane yield |
Alk | total alkalinity |
ANOVA | Analysis of variance |
BOD | biological oxygen demand |
CH4 | methane |
C/N | carbon to nitrogen ratio |
H2 | hydrogen |
H/SRT | hydraulic/solid retention time |
K | rate constant |
NH3/NH4 | ammonia/um |
Pb | lead |
sulfate | |
TKN | total Kjeldahl Nitrogen |
TOC | total organic carbon |
TWAS | tannery waste activated sludge |
T/VS | total/volatile solids |
AAE | acetic acid equivalents |
AMs | aceticlastic methanogens |
Bo | biodegradability |
CCD | central composite design |
Cl | chloride |
Cu | copper |
HMs | hydrogenotrophic methanogens |
ISR | inoculum to substrate ratio |
Mg | magnesium |
Ni | nickel |
r | Pearson’s correlation |
SRB | sulfate reducing bacteria |
TL | tanning liquor |
TP | total phosphate |
TWW | tannery wastewater |
UACF | upflow anaerobic contact filter |
AD/AcoD | anaerobic digestion/codigestion |
ASBR | anaerobic sequencing batch reactor |
BMP | biochemical methane potential |
Ca | calcium |
COD | chemical oxygen demand |
Fe | iron |
sulfide species | |
IOT | integrated ostrich tannery |
Na | sodium |
OLR | organic loading rate |
S0 | elementary sulfur |
SWW | slaughterhouse wastewater |
TN | total nitrogen |
TS | total solids |
TWWTP | TWW treatment plant |
UASB | upflow anaerobic sludge blanket |
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Parameter | Batch 1 | Batch 2 | Batch 3 | Batch 4 | Batch 5 | Batch 6 | Mean | SD |
---|---|---|---|---|---|---|---|---|
TOC (mg/L) | 2467 | 3380 | 4530 | 9080 | 485 | 820 | 3460 | 3148 |
COD (mg/L) | 7945 | 8143 | 7903 | 15690 | 4387 | 7235 | 8551 | 3768 |
BOD (mg/L) | 3532 | 1472 | 1542 | 1515 | 1531 | 1552 | 1857 | 821 |
VOAt (mg/L AAE) | 3070 | 2800 | 2440 | 2480 | 2120 | 1800 | 2452 | 456 |
TN (mg/L) | 440 | 235 | 180 | 260 | 220 | 530 | 311 | 140 |
TAN (mg/L NH3-N) | 18.8 | 13.5 | 16.2 | 41.0 | 13.2 | 9.60 | 18.7 | 11.3 |
NO3 (mg/L) | 143.8 | 39.0 | 28.6 | 18.7 | 11.5 | 54.7 | 49.4 | 48.7 |
TP (mg/L PO42−-P) | 6.65 | 5.10 | 5.05 | 17.8 | 5.00 | 4.90 | 7.41 | 5.11 |
(mg/L) | 1114 | 626 | 352 | 424 | 173 | 1186 | 646 | 417 |
HS− (mg/L) | ND | 2.38 | 5.70 | 2.20 | 0.00 | 0.12 | 2.08 | 2.31 |
Cl (mg/L) | 2038 | 1547 | 1294 | 1022 | 911 | 2369 | 1530 | 576 |
TS (g/L) | 7.85 | 8.07 | 8.38 | 19.4 | 5.53 | 4.69 | 8.98 | 5.30 |
TVS (g/L) | 3.61 | 4.06 | 4.97 | 14.6 | 2.82 | 2.32 | 5.40 | 4.61 |
K (mg/L) | 11.7 | 19.9 | 13.2 | 12.3 | 10.7 | 6.6 | 12.4 | 4.3 |
Na (mg/L) | 1477 | 1315 | 1953 | 2789 | 964 | 754 | 1542 | 740 |
Fe (µg/L) | 3272 | 3081 | 606 | 497 | 193 | 282 | 1322 | 1446 |
Ca (mg/L) | 11.7 | 24.0 | 24.2 | 6.9 | 17.6 | 16.8 | 16.9 | 6.8 |
Mg (mg/L) | 19.4 | 15.5 | 39.5 | 55.3 | 14.9 | 13.2 | 26.3 | 17.2 |
Zn (µg/L) | 1568 | 674 | 439 | 401 | 229 | 198 | 585 | 511 |
Cu (µg/L) | 304 | 136 | 16.6 | 65.9 | 12.7 | 12.1 | 91.2 | 115 |
Co (µg/L) | 7.7 | 4.7 | 1.6 | 1.9 | 44.2 | 1.9 | 10.3 | 16.8 |
Cd (µg/L) | 2.27 | 1.08 | 0.18 | 0.27 | 0.18 | 0.18 | 0.69 | 0.85 |
Ni (µg/L) | 73.1 | 18.4 | 18.7 | 21.3 | 5.6 | 8.4 | 24.2 | 24.7 |
Cr (µg/L) | 766 | 57 | 1094 | 350 | 584 | 136 | 498 | 395 |
Pb (µg/L) | 8.4 | 2.3 | 4.8 | 6.8 | 5.2 | 4.1 | 5.3 | 2.1 |
Al (µg/L) | 1798 | 2366 | 583 | 624 | 85 | 101 | 926 | 941 |
Alk (g/L CaCO3) | 245 | 236 | 330 | 264 | 297 | 308 | 280 | 37.0 |
EC (mS/cm) | 8.22 | 8.27 | 8.81 | 11.87 | 4.04 | 3.61 | 7.47 | 3.13 |
pH | 6.49 | 6.73 | 7.33 | 7.09 | 6.92 | 6.93 | ND | ND |
TVS:TS | 0.46 | 0.50 | 0.59 | 0.76 | 0.51 | 0.49 | ND | ND |
BOD:COD | 0.44 | 0.18 | 0.20 | 0.10 | 0.35 | 0.21 | ND | ND |
C:N | 5.61 | 14.38 | 25.17 | 34.92 | 2.20 | 1.55 | ND | ND |
VFA:Alk | 12.5 | 11.9 | 7.39 | 9.39 | 7.14 | 5.84 | ND | ND |
7.13 | 13.0 | 22.4 | 37.0 | 25.3 | 6.10 | ND | ND | |
COD:TVS | 2.20 | 2.00 | 1.59 | 1.07 | 1.56 | 3.12 | ND | ND |
Reactor | B:ISR | Biogas Yield | Methane Yield | Biodegradability Indicators (% Reduction) | ||||||
---|---|---|---|---|---|---|---|---|---|---|
TOC | Sulfate | TS | VS | COD | ||||||
(mg/L) | (mL/gVSadded) | (mL/gVSadded) | % | (%) | (%) | (%) | (%) | (%) | ||
R1 | 1960 | 2.5 | 129 | 12.0 | 9.30 | 87.6 | 59.7 | 11.7 | 15.2 | 16.6 |
R2 | 1335 | 2.0 | 4.97 | 1.71 | 34.4 | 93.1 | 63.4 | 11.5 | 19.2 | 13.8 |
R3 | 710 | 2.5 | 83.6 | 17.0 | 20.3 | 76.2 | 77.1 | 20.1 | 28.5 | 19.2 |
R4 | 1335 | 3.0 | 79.8 | 25.7 | 32.2 | 81.3 | 73.6 | 19.3 | 26.7 | 24.4 |
R5 | 710 | 4.0 | 361 | 93.3 | 25.9 | 82.5 | 68.0 | 29.1 | 40.9 | 52.0 |
R6 | 1335 | 5.0 | 180 | 41.5 | 23.1 | 88.3 | 81.1 | 26.0 | 55.0 | 10.8 |
R7 | 1960 | 4.0 | 110 | 19.5 | 17.7 | 77.1 | 80.4 | 28.3 | 33.3 | 14.9 |
R8 | 1335 | 3.0 | 337 | 146 | 43.4 | 82.7 | 80.4 | 26.1 | 30.5 | 43.6 |
R9 | 1335 | 3.0 | 260 | 100 | 38.5 | 69.0 | 85.3 | 49.2 | 51.7 | 24.6 |
R10 | 1335 | 3.0 | 265 | 102 | 38.5 | 61.3 | 79.6 | 37.0 | 40.8 | 43.0 |
R11 | 1335 | 3.0 | 280 | 103 | 36.9 | 75.3 | 75.0 | 35.8 | 37.7 | 24.3 |
R12 | 2000 | 3.0 | 9.13 | 1.02 | 11.2 | 23.2 | 49.3 | 19.0 | 27.5 | 39.3 |
R13 | 665 | 3.0 | 290 | 130 | 44.8 | 78.5 | 77.8 | 29.0 | 35.4 | 25.5 |
Models | Std Dev | Overall F Test p-Value | F Test (LOF) p Value | R2 | Adj R2 | Adeq Prec | AIC |
---|---|---|---|---|---|---|---|
Biogas-Quadratic | 2.41 | 0.0012 | 13.8 | 0.87 | 0.81 | 15.4 | 71.9 |
CH4-Quadratic | 0.005 | 0.032 | 4.87 | 0.77 | 0.61 | 6.4 | −83.6 |
TOC-Mean | ND | ND | ND | ND | ND | ND | 112 |
Sulfate-Quadratic | 6.87 | 0.027 | 4.72 | 0.71 | 0.55 | 7.70 | 99.3 |
TS-Mean | ND | ND | ND | ND | ND | ND | ND |
VS-Mean | ND | ND | ND | ND | ND | ND | ND |
COD-Quadratic | 0.01 | 0.003 | 10.7 | 0.84 | 0.76 | 10.9 | −68.7 |
Reactor | Model | Kinetic Parameters | Adj R2 | p Value Prob > F | AIC | RMSE | ||||
---|---|---|---|---|---|---|---|---|---|---|
A (mLCH4/gVS) | µm (mLCH4/gVSd) | λ (d) | K | n | ||||||
R1 (1960/2.5) | Cone | 11.5 | ND | ND | 0.043 | 4.92 | 0.965 | 0.44 | 90.5 | 0.46 |
Logistic | 11.2 | 0.61 | 14.4 | ND | ND | 0.956 | 0.41 | 105 | 0.51 | |
First order | 13.0 | 0.03 | ND | ND | ND | 0.827 | 0.08 | 195 | 1.02 | |
Gompertz | 3.55 | 0.69 | 13.5 | ND | ND | 0.676 | 0.23 | 235 | 1.38 | |
R3 (710/2.5) | Logistic | 16.7 | 3.63 | 20.9 | ND | ND | 0.999 | 0.50 | 99.0 | 0.11 |
Cone | 16.7 | ND | ND | 0.043 | 21.9 | 0.999 | 0.50 | 99.2 | 0.11 | |
Gompertz | 6.14 | 1.76 | 22.7 | ND | ND | 0.999 | 0.50 | 99.2 | 0.11 | |
First order | 28.8 | 0.02 | ND | ND | ND | 0.831 | 0.18 | 251 | 1.57 | |
R4 (1335/3.0) | Logistic | 26.5 | 1.06 | 12.9 | ND | ND | 0.955 | 0.45 | 209 | 1.13 |
Gompertz | 9.99 | 0.36 | 20.6 | ND | ND | 0.951 | 0.45 | 213 | 1.18 | |
Cone | 28.2 | ND | ND | 0.04 | 3.25 | 0.949 | 0.46 | 217 | 1.20 | |
First order | 47.3 | 0.015 | ND | ND | ND | 0.883 | 0.24 | 272 | 1.84 | |
R5 (710/4.0) | Gompertz | 51.2 | 4.20 | 2.75 | ND | ND | 0.996 | 0.50 | 183 | 0.93 |
First order | 139 | 0.172 | ND | ND | ND | 0.984 | 0.43 | 270 | 1.82 | |
Logistic | 138 | 13.40 | 0 | ND | ND | 0.979 | 0.38 | 286 | 2.06 | |
Cone | 146 | ND | ND | 0.27 | 1.22 | 0.966 | 0.47 | 319 | 2.65 | |
R6 (1335/5.0) | Gompertz | 15.3 | 1.71 | 7.80 | ND | ND | 0.968 | 0.45 | 222 | 1.25 |
Cone | 41.9 | ND | ND | 0.112 | 3.78 | 0.966 | 0.44 | 225 | 1.29 | |
Logistic | 41.6 | 4.32 | 4.59 | ND | ND | 0.961 | 0.42 | 234 | 1.37 | |
First order | 43.3 | 0.083 | ND | ND | ND | 0.883 | 0.23 | 306 | 2.40 | |
R7 (1960/4.0) | Logistic | 20.3 | 0.88 | 24.5 | ND | ND | 0.962 | 0.46 | 165 | 0.81 |
Cone | 21.1 | ND | ND | 0.03 | 5.60 | 0.960 | 0.47 | 168 | 0.83 | |
Gompertz | 7.72 | 0.31 | 32.2 | ND | ND | 0.960 | 0.47 | 169 | 0.83 | |
First order | 25.0 | 0.02 | ND | ND | ND | 0.763 | 0.04 | 285 | 2.04 | |
R8; R9; R10 & R11 (1335/3.0) | Logistic | 117 | 4.82 | 26.7 | ND | ND | 0.987 | 0.50 | 314 | 2.55 |
Cone | 124 | ND | ND | 0.025 | 5.68 | 0.982 | 0.48 | 337 | 3.04 | |
Gompertz | 46.6 | 1.55 | 35.3 | ND | ND | 0.979 | 0.49 | 347 | 3.29 | |
First order | 38.0 | 0.021 | ND | ND | ND | 0.437 | 0.03 | 648 | 4.81 | |
R13 (665/3.0) | Logistic | 129 | 17.5 | 3.12 | ND | ND | 0.991 | 0.47 | 265 | 1.75 |
Gompertz | 47.5 | 6.43 | 5.55 | ND | ND | 0.991 | 0.49 | 267 | 1.77 | |
Cone | 130 | ND | ND | 0.15 | 3.44 | 0.990 | 0.50 | 271 | 1.83 | |
First order | 132 | 0.125 | ND | ND | ND | 0.939 | 0.29 | 389 | 4.54 |
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Mpofu, A.B.; Kibangou, V.A.; Kaira, W.M.; Oyekola, O.O.; Welz, P.J. Anaerobic Co-Digestion of Tannery and Slaughterhouse Wastewater for Solids Reduction and Resource Recovery: Effect of Sulfate Concentration and Inoculum to Substrate Ratio. Energies 2021, 14, 2491. https://doi.org/10.3390/en14092491
Mpofu AB, Kibangou VA, Kaira WM, Oyekola OO, Welz PJ. Anaerobic Co-Digestion of Tannery and Slaughterhouse Wastewater for Solids Reduction and Resource Recovery: Effect of Sulfate Concentration and Inoculum to Substrate Ratio. Energies. 2021; 14(9):2491. https://doi.org/10.3390/en14092491
Chicago/Turabian StyleMpofu, Ashton B., Victoria A. Kibangou, Walusungu M. Kaira, Oluwaseun O. Oyekola, and Pamela J. Welz. 2021. "Anaerobic Co-Digestion of Tannery and Slaughterhouse Wastewater for Solids Reduction and Resource Recovery: Effect of Sulfate Concentration and Inoculum to Substrate Ratio" Energies 14, no. 9: 2491. https://doi.org/10.3390/en14092491