Hydrothermal, acidic, and alkaline pretreatment of waste flower-mix for enhanced biogas production: a comparative assessment

Abstract Biogas yield obtained from anaerobic digestion of swine wastewater (SWW) needs to be increased to produce electrical energy. To enhance biogas and prevent pollution, use of mixed culture microalgae grown in wastewater (MWW) with SWW has attracted a lot of interest. This research was focused on the possibility of utilizing MWW. Six experiments using raw SWW and MWW, and their co-digestion were conducted on a laboratory scale in one-litre reactors with the ratio of inoculum and substrate of 70:30 under without and with alkaline pretreatment (using 3% NaOH for pH adjustment every 15 min at pH 11 for 3 h). The results showed that co-digestion had the major effect on increasing biogas and methane yields (0.735 and 0.326 m3/kg of volatile solids (VS) removed), and the highest chemical oxygen demand and VS removal (60.29% and 63.17%). For pretreatment, the effect of ammonia inhibition at a high pH of 11 had more influence on biodegradation than the effect of destruction of MWW's cell walls, resulting in a low biogas production of pretreated MWW and pretreated co-digestion. These findings affirm the potential of co-digestion, and the possibility of using both single and co-substrate MWW. Pretreatment could be improved at a lower alkaline pH condition. A pilot scale of co-digestion should be performed.

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Effect of Thermo-Chemical Pretreatment of Kenyan Market Waste on Mesophillic Biogas Production

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset2182103 ◽

2021 ◽

pp. 22-31

Author(s):

Kamau J. M ◽

Mbui D. N ◽

Mwaniki J. M ◽

Waswa G. A.

Keyword(s):

Acid Hydrolysis ◽

Large Scale ◽

Biogas Production ◽

Alkaline Pretreatment ◽

Chemical Pretreatment ◽

Chemical Methods ◽

Thermochemical Pretreatment ◽

Naoh Pretreatment ◽

Chemical Pretreatments ◽

Vegetable Market Waste

Effects of pretreatment on the anaerobic digestion of waste fruit and vegetable market waste were investigated in biogas production by batch experiments. The pretreatment was NaOH and HCl thermochemical, thermal and chemical methods. The wastes were chopped and blended before loading to the digester. Acid hydrolysis was done by adding 20ml 0.1M HCl with thorough mixing before purging with CO2 and sealing. Alkaline pretreatment was done using 1M NaOH. In both cases, the setups were exposed to heat at 1000C for 12hours, after which they were allowed to cool for 3 hours. The pH was modified to 6.7 – 7.2 before loading the inoculum and studying biogas generation. The large-scale setups with 1.0l, 1.5l, 5l and 10l capacity were studied for biogas generation. The results obtained show that thermochemical pretreatment results in more cumulative biogas production at 6200ml, followed by thermal at 4900ml and then chemical pretreatments at 3750ml for 500g mixed fruits and vegetable market wastes. Alkaline pretreatment is more efficient compared to acidic hydrolysis though highly influenced by proximate properties of the wastes and operation pH. The large-scale pretreatment resulted in 34500ml and 31400ml cumulative biogas from HCl and NaOH pretreatment. In conclusion, thermochemical pretreatment of market waste results in increased biogas generation resulting from hemicellulose breakdown and disrupting lignin-hemicellulose ether bonds in acid hydrolysis. In contrast, alkaline pretreatment leads to swelling of lignocelluloses and partial lignin solubilization lignin breakdown. The overall biogas generation depends on proximate waste matter and digester operation pH.

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Enhanced Biogas Production and Dewaterability from Sewage Sludge with Alkaline Pretreatment at Mesophilic and Thermophilic Temperatures

Water Air & Soil Pollution ◽

10.1007/s11270-018-3726-0 ◽

2018 ◽

Vol 229 (3) ◽

Cited By ~ 4

Author(s):

Tianfeng Wang ◽

Bingqing Xu ◽

Xinyun Zhang ◽

Qiyong Yang ◽

Bingjie Xu ◽

...

Keyword(s):

Sewage Sludge ◽

Biogas Production ◽

Alkaline Pretreatment

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Biogas Production from Sunflower Head and Stalk Residues: Effect of Alkaline Pretreatment

Molecules ◽

10.3390/molecules25010164 ◽

2019 ◽

Vol 25 (1) ◽

pp. 164 ◽

Cited By ~ 2

Author(s):

Marinela Zhurka ◽

Apostolos Spyridonidis ◽

Ioanna A. Vasiliadou ◽

Katerina Stamatelatou

Keyword(s):

Biogas Production ◽

Liquid Fraction ◽

Alkaline Pretreatment ◽

Second Phase ◽

Lignocellulosic Substrate ◽

Stirred Tank Reactors ◽

Batch Tests ◽

Volatile Solids ◽

Negative Effect ◽

Whole Slurry

Sunflower residues are considered a prominent renewable source for biogas production during anaerobic digestion (AD). However; the recalcitrant structure of this lignocellulosic substrate requires a pretreatment step for efficient biomass transformation and increased bioenergy output. The aim of the present study was to assess the effect of alkaline pretreatment of various parts of the sunflower residues (e.g., heads and stalks) on their methane yield. Experimental data showed that pretreatment at mild conditions (55 °C; 24 h; 4 g NaOH 100 g−1 total solids) caused an increase in the biochemical methane potential (BMP) of both heads and stalks of the sunflower residues as determined in batch tests. The highest methane production (268.35 ± 0.11 mL CH4 g−1 volatile solids) was achieved from the pretreated sunflower head residues. Thereafter; the effect of alkaline pretreatment of sunflower head residues was assessed in continuous mode; using continuous stirred-tank reactors (CSTRs) under two operational phases. During the first phase; the CSTRs were fed with the liquid fraction produced from the pretreatment of sunflower heads. During the second phase; the CSTRs were fed with the whole slurry resulting from the pretreatment of sunflower heads (i.e., both liquid and solid fractions). In both operating phases; it was observed that the alkaline pretreatment of the sunflower head residues had a negligible (phase I) or even a negative effect on biogas production; which was contradictory to the results of the BMP tests. It seems that; during alkaline pretreatment; this part of the sunflower residues (heads) may release inhibitory compounds; which induce a negative effect on biogas production in the long term (e.g., during continuously run digesters such as CSTR) but not in the short-term (e.g., batch tests) where the effect of the inoculum may not permit the inhibition to be established.

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Synergistic effect of alkaline pretreatment and magnetite nanoparticle application on biogas production from rice straw

Bioresource Technology ◽

10.1016/j.biortech.2018.12.051 ◽

2019 ◽

Vol 275 ◽

pp. 288-296 ◽

Cited By ~ 22

Author(s):

Muhammad Junaid Khalid ◽

Zeshan ◽

Adeel Waqas ◽

Ismat Nawaz

Keyword(s):

Synergistic Effect ◽

Rice Straw ◽

Biogas Production ◽

Alkaline Pretreatment ◽

Magnetite Nanoparticle

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Improving biodegradability and biogas production of miscanthus using a combination of hydrothermal and alkaline pretreatment

Industrial Crops and Products ◽

10.1016/j.indcrop.2019.111985 ◽

2020 ◽

Vol 144 ◽

pp. 111985 ◽

Cited By ~ 9

Author(s):

Yanwen Xue ◽

Qi Li ◽

Yu Gu ◽

Hancheng Yu ◽

Yalei Zhang ◽

...

Keyword(s):

Biogas Production ◽

Alkaline Pretreatment

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