scholarly journals Effect of Acid-Alkaline and Thermal Pre-treatment to Cassava Pulp Feed for Batch Reactors in Optimization of Bio-Methane Yield

2018 ◽  
pp. 51-60
Author(s):  
Htay A. Pyae ◽  
Nittaya Boontian ◽  
Usa Yingchon ◽  
Chatlada Piasai
Keyword(s):  
Oxygen Demand ◽  
High Volume ◽  
Methane Yield ◽  
Total Alkalinity ◽  
Batch Reactors ◽  
Biogas Yield ◽  
Mixing Ratios ◽  
Cassava Pulp ◽  
Hydrolytic Bacteria ◽  
Pre Treatment

Cassava starch mills in Nakhon Ratchasimaprovince operate biogas plants to generate renewable energy from surplus cassava pulp using anaerobic digestion (AD) technologies. However, the biogas yields fluctuate and digestion failure occurs due to suboptimal digester configuration and lack of understanding of the specific properties of cassava pulp substrate. This study used acid-alkaline and thermal pre-treatment to modify the cassava pulp substrate to enhance biogas yields. Concentrated 36N sulphuric acid (H2SO4) and 20M sodium hydroxide (NaOH) was chosen as an acid-alkaline pre-treatment to adjust to the required pH for the substrates, and 45 minat 200 ̊C for the thermal pre-treatment. Extreme pH adjusted substrates such as T1, T2, T12 and T13 required both acid and alkali in high volume, and inhibition occurred from both acid and alkali resulting in retardation of fermentation by hydrolytic bacteria, a lower volatile fatty acid to total alkalinity ratio (VFA/TA), more depletion of reducing sugars and a lower bio-methane yield. The results showed Soluble Chemical Oxygen Demand (SCOD) obtained from decomposition of lignocellulosic structure of fresh cassava pulp by combined thermal-chemical pre-treatment, was found highest in T2 which was pre-treated at pH2 having more than 100 g L-1. Though SCOD could be enhanced by acid-alkaline pre-treatment, it led to inhibition driven by radicals of acid and alkaline. Three different mixing ratios, i.e. 3%, 5%, and 10%(w/v) were compared against without pre-treated samples, and found 5%Total Solids (TS)was most suitable after subjected to acid-alkaline pre-treatment and produced biogas yield at 4125.2 mL kg-1TS in batch digestion for 21 d. Pre-treatment was found increase bio-methane by up to a factor of six.

scholarly journals Effect Of Alkaline Pre-Treatment On Cassava Pulp For Optimum Biogas Production

2019 ◽  
Vol 8 (2) ◽  
pp. 5919-5923
Keyword(s):  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Treatment Method ◽  
Batch Mode ◽  
Biogas Yield ◽  
Cassava Pulp ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment

(Being produced in vast quantity as one of by-product from cassava starch processing chains, cassava pulp has great potential for energy recovery by harnessing biogas through anaerobic digestion (AD). This study aims to enhance biogas production by comparative investigation in batch mode digestion. 5%TS w/v of cassava pulp mixed with mill effluent were pre-treated with 10 molar potassium hydroxide (KOH), sodium hydroxide (NaOH), and calcium hydroxide (Ca(OH)2) solution for 6 hours contact time. Effects of different alkaline pre-treatment on cassava substrate were assessed in total dissolved solid (TDS), soluble chemical oxygen demand (SCOD), Volatile Fatty Acids to Alkalinity ratio (VFA/TA), and reducing sugars. Daily accumulated biogas yield was taken as final indicator of the effect of different pre-treatment. KOH pre-treatment in pH 11 resulted highest dissolved solid 13.07 mg/L, and improved soluble chemical oxygen demand (SCOD) formation up to 75.61% (480,000 mg/L) than control substrate. The experiment revealed peak biogas production by KOH pre-treated substrate was found at day 6 after digestion executed, and achieved 546 ml. The finding proves out of different pre-treatment method applicable to cassava pulp, KOH pre-treatment could realistically increase biogas yield for cassava mills. Biogas production increased up to 101%, 92%, and 70% using KOH, Ca(OH)2 and NaOH respectively. However, when future provision to the technology for AD system and design is concerned, the choice of highly reactive alkali could lead to complication in the system.

Biological treatment of pharmaceutical wastewater from the antibiotics industry

2013 ◽  
Vol 69 (4) ◽  
pp. 855-861 ◽  
Author(s):  
O. Lefebvre ◽  
X. Shi ◽  
C. H. Wu ◽  
H. Y. Ng
Keyword(s):  
Loading Rate ◽  
Oxygen Demand ◽  
Organic Loading Rate ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Pharmaceutical Wastewater ◽  
Refractory Compounds ◽  
Treated Effluent ◽  
Discharge Regulation ◽  
Pre Treatment

Pharmaceutical wastewater generated by an antibiotics (penicillin) company was treated by aerobic membrane bioreactors (MBRs) and sequencing batch reactors (SBRs). At a low organic loading rate of 0.22 kg-COD m−3d−1, both types of reactors were capable of treating the wastewater such that the treated effluent met the discharge regulation except for the total dissolved solids. However, when the loading rate was increased to 2.92 kg-COD m−3d−1, foaming issues resulted in unstable performance. Overall, the MBRs achieved better solid removal but the SBRs performed better in regards to the degradation of aromatic compounds, as determined by UV absorbance (UVA). Finally, ozonation was applied on two different streams and showed promise on the strong stream – that corresponds to the formulation effluent and contains most of the biorefractory compounds. Ozonation successfully reduced the UVA, lowered the pH and increased the biochemical oxygen demand : chemical oxygen demand (BOD5 : COD) ratio of the strong stream. However, it was less efficient on the effluent having undergone pre-treatment by a biofilter due to a lack of selectivity towards refractory compounds.

scholarly journals Effect of alkaline pre-treatment on the anaerobic biodegradability of coffee husk

2019 ◽  
pp. 36-41
Author(s):  
K De la Cruz-Martorell ◽  
Y Gómez-Salcedo ◽  
Y Santander ◽  
D J Catagua Mera ◽  
JCD Mendoza ◽  
...  
Keyword(s):  
Hydraulic Retention Time ◽  
Loading Rate ◽  
Methane Yield ◽  
Organic Loading Rate ◽  
Batch Reactors ◽  
Continuous Stirred Tank Reactor ◽  
Coffee Husk ◽  
Anaerobic Biodegradability ◽  
Continuous Stirred Tank ◽  
Pre Treatment

The present paper deals with the mono-digestion of coffee husk during the operation of batch reactors and semi-continuous stirred tank reactor (S-CSTR) using both pre-treated residual at 3% Ca(OH)2 and without pre-treatment. The semi-continuous operation was carried out in 4 stages at different organic loading rate (OLR, [gVS L-1 d-1]) and hydraulic retention time (HRT, [d]) (OLR:HRT) ratios (0.1:90, 0.2:90, 0.2:45 and 0.2:30). As a result of the pre-treatment, up to 223% of the organic matter solubilisation was obtained. However, pre-treatment did not provide better results in biodegradability, observing a negative trend in methane yield when operating in S-CSTR, due to the accumulation of compounds from the fractionation of the lignin as is the case of polyphenols. The operation was further developed using the residual without pre-treatment. The highest methane yield was obtained at 45:0.2 when using the residual without pre-treatment being with 277 mLCH4 gVS -1, for a methane productivity of 1.1 L L-1 d-1. When implementing the 30:0.2 ratio, a biomass washout was observed in the system, so it is recommended to operate at low OLR and high HRT when treating solid coffee wastes.

scholarly journals Optimisation and Modelling of Anaerobic Digestion of Whiskey Distillery/Brewery Wastes after Combined Chemical and Mechanical Pre-Treatment

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 492 ◽  
Author(s):  
Burcu Gunes ◽  
Maxime Carrié ◽  
Khaled Benyounis ◽  
Joseph Stokes ◽  
Paul Davis ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
High Strength ◽  
Batch Mode ◽  
Biogas Yield ◽  
Mixing Ratios ◽  
Before And After ◽  
Liquid Residue ◽  
Spent Grain ◽  
Distillery Waste ◽  
Pre Treatment

Whiskey distillery waste streams consisting of pot ale (liquid residue) and spent grain (solid residue) are high strength organic wastes and suitable feedstock for anaerobic digestion (AD) from both economic and environmental stand points. Anaerobic digestion of pot ale and pot ale/spent grain mixtures (with mixing ratios of 1:1, 1:3, and 1:5 by wet weight) was performed after implementation of a novel hybrid pre-treatment (combined chemical and mechanical) in order to modify lignocellulosic structure and ultimately enhance digestion yield. Lignin, hemicellulose, and cellulose fractions were determined before and after chemical pre-treatment. Effects of different inoculum rates (10–30–50% on wet basis) and beating times (0–7.5–15 min) on anaerobic digestion of pot ale alone and of pot ale/spent grain mixtures were investigated in lab scale batch mode with a major focus of optimising biogas yield by using response surface methodology (RSM) in Design Expert Software. The highest biogas yields of 629 ± 8.5 mL/g vs. (51.3% CH4) and 360 ± 10 mL/g vs. (55.0 ± 0.4) with anaerobic digestion of pot ale alone and spent grain mix after 1M NaOH and 7.5 min beating pre-treatments with 50% inoculum ratio respectively. The optimum digestion conditions to maximise the biogas quality and quantity were predicted as 10 and 13 min beating times and 32 and 38 °C digestion temperatures for anaerobic digestion of pot ale alone and spent grain mix respectively.

scholarly journals Optimization of anaerobic co-digestion of sewage sludge using bio-chemical substrates

2018 ◽  
Author(s):  
◽  
Nhlanganiso Ivan Madondo
Keyword(s):  
Sewage Sludge ◽  
Energy Content ◽  
Oxygen Demand ◽  
Methane Yield ◽  
Batch Experiment ◽  
Batch Test ◽  
System Productivity ◽  
Biogas Yield ◽  
Volatile Solids ◽  
Substrate To Inoculum Ratio

The anaerobic process is increasingly becoming a subject for many as it reduces greenhouse gas emissions and recovers carbon dioxide energy as methane. Even though these benefits are attainable, proper control and design of the process variables has to be done in order to optimize the system productivity and improve stability. The aim of this research was to optimize methane and biogas yields on the anaerobic co-digestion of sewage sludge using bio-chemical substrates as co-substrates. The first objective was to find the bio-chemical substrate that will generate the highest biogas and methane yields. The anaerobic digestion of these substrates was operated using 6 L digesters at 37.5℃. The substrate which generated the highest biogas and methane yield in the first batch experiment was then used for the second batch test. The objective was to optimize the anaerobic conditions (substrate to inoculum ratio, co-substrate concentration and temperature) in-order to optimize the biogas and methane yields. The second batch test was achieved using the conventional One-Factor-At-A-Time (OFAT) and the Design of Experiment (DOE) methods. Final analysis showed that the bio-chemical substrates could be substrates of interest to biogas generators. Amongst the substrates tested in the first batch experiment glycerol (Oleo-Chemical Product waste) generated the highest methane and biogas yields of 0.71 and 0.93 L. (g volatile solids added)-1, respectively. It was believed that glycerol contains significant amount of other organic substances such as lipids that have higher energy content than the other bio-chemical substrates, thus generating larger biogas and methane yields. Moreover, digestion of sewage sludge alone produced biogas yields of 0.19 L /g VS and 0.33 L/g COD, and methane yields of 0.16 L/g VS and 0.28 L/g COD. Generally, co-digestion yields were higher than digestion yields of sewage alone. Using the OFAT method the results of the second batch test on glycerol demonstrated highest amounts of volatile solids (VS) reduction, chemical oxygen demand (COD) reduction, biogas yield and methane yield of 99.7%, 100%, 0.94 L (g VS added)-1 and 0.75 L (g VS added)-1 at a temperature, substrate to inoculum ratio and glycerol volume of 50℃, 1 (on VS basis) and 10 mL, respectively. Above 22 mL and substrate to inoculum ratio of 1, the process was inhibited. The DOE results suggested that the highest methane and biogas yields were 0.75 and 0.94 L (g VS added)-1, respectively. These results were similar to the OFAT results, thus the DOE software may be used to define the biogas and methane yields equations for glycerol. In conclusion, anaerobic co-digestion of bio-chemical substrates as co-substrates on sewage sludge was successfully applied to optimize methane and biogas yields.

scholarly journals Evaluation of Biogas through Chemically Treated Cottonseed Hull in Anaerobic Digestion with/without Cow Dung: An Experimental Study

2021 ◽  
Author(s):  
Venkateshkumar R ◽  
Shanmugam S ◽  
Veerappan AR
Keyword(s):  
Anaerobic Digestion ◽  
Sodium Hydroxide ◽  
Calcium Hydroxide ◽  
Biogas Production ◽  
Cow Dung ◽  
Batch Reactors ◽  
Biogas Yield ◽  
Cottonseed Hull ◽  
Pre Treatment ◽  
Feedstock Material

Abstract Cow dung is generally used as the feedstock material for the anaerobic digestion to produce biogas. A selection of alternate biomass material is needed to reduce the consumption or to eliminate the use of cow dung. Recently, cottonseed hull has been considered as the primary substrate to produce biogas. In this paper, the effect of biogas production on anaerobic co-digestion of cow dung with pre-treated cottonseed hull using different concentrations of sulfuric acid, hydrochloric acid, hydrogen peroxide, and acetic acid is investigated. Sodium hydroxide and calcium hydroxide are used at different concentrations for pre-treatment of cottonseed hull. The enhancement of biogas production from the batch reactors at mesophilic temperature (35 ± 2 ℃) is observed for mono- and co-digestion of cow dung with treated cottonseed hull. Maximum biogas yield is achieved for the treated cottonseed hull at 6% sodium hydroxide during mono digestion and at 6% calcium hydroxide during co-digestion.

Bioconversion of Dried Leaves from Algerian Date Palm (Phoenix dactylifera L.) to Biogas by Anaerobic Digestion

2019 ◽  
Vol 41 ◽  
pp. 131-144
Author(s):  
Mohammed Djaafri ◽  
Slimane Kalloum ◽  
Ahmed Elamine Soulimani ◽  
Mostefa Khelafi
Keyword(s):  
Anaerobic Digestion ◽  
Date Palm ◽  
Biogas Production ◽  
Stable Process ◽  
Production Capacity ◽  
Oxygen Demand ◽  
Phoenix Dactylifera ◽  
Total Alkalinity ◽  
Process Stability ◽  
Biogas Yield

This work aimed to study anaerobic digestion of a new substrate made from the waste of Algerian date palm (Phoenix dactyliferaL.) in order to evaluate its biogas production capacity. The lignocellulosic component biodegradability and the process stability were also tested. Two reactors were launched with the same concentration of 20g total solid (TS)/L. A physical pre-treatment (grinding) of dried leaves lowered the substrate size below 2 mm. The theoretical methane yield (499 - 538 mL CH4/g of Volatile Solids (VS)) indicated a high substrate methanogen potential. The tested methane and biogas yield reached 130±6 mL CH4/gVS and 197±6 mL/g VS respectively. The biodegradability through the volatiles solid reduction was 29%. The total alkalinity (TA) value increased from the beginning to the end, due to the substrate nature which gave a high buffering capacity of the medium. During the stable process, a higher Chemical Oxygen Demand (COD) removal was reached with a value of 77.58%. The majority of the biogas yield was generated during the same period, which confirmed that the anaerobic digestion process stability is indispensable. Finally, this study was an opportunity to better exploit local by-products for the bioenergy production.

scholarly journals Effect of Mixture Ratio of Food Waste and Vetiver Grass on Biogas Production

2020 ◽  
pp. 40-48
Author(s):  
Mayura Srikanlayanukul ◽  
Parinda Suksabye
Keyword(s):  
Food Waste ◽  
Biogas Production ◽  
Methane Yield ◽  
Total Alkalinity ◽  
Vetiver Grass ◽  
Digestion Time ◽  
Mixture Ratio ◽  
Biogas Yield ◽  
Working Volume ◽  
Percentage Ratio

The objectives of this research were to study the optimum percentage ratios of food waste and vetiver grass (Vetiveria zizaniodes (L.) Nash) for biogas production and process stability in anaerobic digestion system. The nine mixture ratios of food waste (FM) and vetiver grass (VG) were 100:0, 80:20, 75:25, 66.67:33.33, 50:50, 33.33:66.67, 25:75, 20:80 and 0:100. The biogas production was subjected to anaerobic batch with working volume of 1.8 L and had digestion time 60 d at 35 ± 2 °C. High specific methane yield of 0.30 L g-1 VS removed was obtained from the fermentation at ratio of FW:VG at 80:20 with C/N ratio of 28.20. The specific methane yield of the single digestion of food waste (100:0) and single digestion of vetiver grass (0:100) were only 0.18 and 0.11 L g-1 VS removed, respectively. It was found that the cumulative methane production of FW: VG ratio of 80:20 was increased 34.89 % and 96.93 % compared to single substrate of food waste and vetiver grass, respectively. The results also showed the highest COD, VS and TS removal with a percentage ratio of FW: VG at 80:20, while the single vetiver grass digestion was the lowest COD, VS and TS removal. VFAs/Total alkalinity ratio of all ratio of food waste to vetiver at digestion time 40 d remained in 0.0895±0.0007 to 0.1944±0.0027 were steadied for this digester. It can be concluded that co-digestion of food waste and vetiver improve the biogas yield and degradation efficiency.

Alkali pre-treatment of Sorghum Moench for biogas production

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Karina Michalska ◽  
Stanisław Ledakowicz
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Total Phenolic ◽  
Methane Generation ◽  
Pre Treatment ◽  
Alkali Hydrolysis ◽  
Almost All

AbstractThis work studies the influence of the alkali pre-treatment of Sorghum Moench — a representative of energy crops used in biogas production. Solutions containing various concentrations of sodium hydroxide were used to achieve the highest degradation of lignocellulosic structures. The results obtained after chemical pre-treatment indicate that the use of NaOH leads to the removal of almost all lignin (over 99 % in the case of 5 mass % NaOH) from the biomass, which is a prerequisite for efficient anaerobic digestion. Several parameters, such as chemical oxygen demand, total organic carbon, total phenolic content, volatile fatty acids, and general nitrogen were determined in the hydrolysates thus obtained in order to define the most favourable conditions. The best results were obtained for the Sorghum treated with 5 mass % NaOH at 121°C for 30 min The hydrolysate thus achieved consisted of high total phenolic compounds concentration (ca. 4.7 g L−1) and chemical oxygen demand value (ca. 45 g L−1). Although single alkali hydrolysis causes total degradation of glucose, a combined chemical and enzymatic pre-treatment of Sorghum leads to the release of large amounts of this monosaccharide into the supernatant. This indicates that alkali pre-treatment does not lead to complete cellulose destruction. The high degradation of lignin structure in the first step of the pre-treatment rendered the remainder of the biomass available for enzymatic action. A comparison of the efficiency of biogas production from untreated Sorghum and Sorghum treated with the use of NaOH and enzymes shows that chemical hydrolysis improves the anaerobic digestion effectiveness and the combined pre-treatment could have great potential for methane generation.

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