scholarly journals Acidogenesis of dairy wastewater at various pH levels

2002 ◽  
Vol 45 (10) ◽  
pp. 201-206 ◽  
Author(s):  
H.-Q. Yu ◽  
H.H.P. Fang
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biomass Yield ◽  
Oxygen Demand ◽  
Dairy Wastewater ◽  
Alcohol Production ◽  
Mixed Liquor ◽  
Influence Of Ph ◽  
Fatty Acids And Alcohols

Continuous experiments were conducted to study the influence of pH in the range 4.0–6.5 on the acidification of dairy wastewater at 37°C with 12 hours of hydraulic retention in an upflow reactor. Results showed that degradation of dairy pollutants increased with pH from pH 4.0 to 5.5. At pH 5.5, 95% of carbohydrate, 82% of protein and 41% of lipid were degraded. Based on chemical oxygen demand (COD), 48.4% of dairy pollutants were converted into volatile fatty acids and alcohols in the mixed liquor, 6.1% into hydrogen and methane in biogas, and the remaining 4.9% into biomass. The biomass yield at pH 5.5 was estimated as 0.32 mg-VSS/mg-COD. Further increase of pH, up to 6.5, increased degradation of carbohydrate, protein and lipid only slightly, but resulted in the lowering of overall acid and alcohol production due to their increased conversion into methane. Acetate, propionate, butyrate and ethanol are the main products of acidogenesis. Productions of propionate and ethanol were favored at pH 4.0−4.5, whereas productions of acetate and butyrate were favored at pH 6.0−6.5.

scholarly journals Effect of Hydrothermal Pretreatment on Volatile Fatty Acids Production from Source-Separated Organics

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 576 ◽  
Author(s):  
Farokh laqa Kakar ◽  
Ehssan Hosseini Koupaie ◽  
Hisham Hafez ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Soluble Substance ◽  
Pretreatment Temperature

The current study investigates the effect of hydrothermal pretreatment (HTP) on acidification of source-separated organics (SSO) in terms of volatile fatty acids (VFAs) production and solubilization. Temperature and retention time for HTP of SSO ranged from 150 to 240 °C and 5 to 30 min, respectively. The soluble substance after hydrothermal pretreatment initially increased, reaching its peak at 210 °C and then declined gradually. The highest overall chemical oxygen demand (COD) solubilization of 63% was observed at “210 °C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210 °C-20 min” compared to 768 mg VFAs/g VSS for raw SSO. Intensification of hydrothermal pretreatment temperature beyond 210 °C resulted in the mineralization of the organics and adversely affected the process.

scholarly journals Characterization of Leachate from a Woodwaste Pile

2005 ◽  
Vol 40 (4) ◽  
pp. 476-483 ◽  
Author(s):  
Wendong Tao ◽  
Ken J. Hall ◽  
Arash Masbough ◽  
Kevin Frankowski ◽  
Sheldon J.B. Duff
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Inorganic Nitrogen ◽  
Oxygen Demand ◽  
Aquatic Life ◽  
Temperature And Precipitation ◽  
Lower Oxygen ◽  
Late Closure ◽  
Leachate Quality

Abstract Leachate was generated when precipitation percolated through a pile of woodwaste, including trimmings, off-specification wood chips, shredded bark and roots, and sawdust from several cedar processing mills. The “young” woodwaste leachate produced in the pile's placement period was amber, acidic (pH 3.4–3.7), nutrient-poor (inorganic nitrogen 1.4–3.2 mg L-1, orthophosphate 3.3–4.3 mg P L-1), of very high oxygen demand (chemical oxygen demand 12,559–14,254 mg L-1, tannin and lignin 3066–5150 mg L-1 as tannic acid, volatile fatty acids 1564–2132 mg L-1), and very toxic to aquatic life (96-h median lethal concentration of 0.74% leachate). The leachate at 1.5 years old in the closure period had lower oxygen demand and higher ammonia, and became less acidic and darker. The leachate had a 5-day biochemical oxygen demand to chemical oxygen demand ratio of 0.33 in the placement period and 0.14 in the late closure period. Volatile fatty acids accounted for 6 to 34% chemical oxygen demand, varying as the pile developed and with woodwaste age. Tannin and lignin accounted for 33 to 45% chemical oxygen demand. More than 98% contaminants were in dissolved form. The monthly variation of leachate quality was likely a result of both temperature and precipitation. pH was significantly correlated to chemical oxygen demand, tannin and lignin, and volatile fatty acids.

Riboflavin boosts fermentative valeric acid generation from waste activated sludge

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3962-3969
Author(s):  
Binfang Shi ◽  
Jingang Huang ◽  
Zhenjiang Yin ◽  
Wei Han ◽  
Shanshan Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Acid Production ◽  
Volatile Fatty Acids ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Valeric Acid ◽  
Waste Activated Sludge ◽  
Acid Generation

Fermentative valeric acid production is a promising way to recycle valuable resources from waste activated sludge (WAS). This study investigated the feasibility of using riboflavin (RF) to enhance volatile fatty acids (VFAs) production, especially valeric acid production from WAS coupled with solid reduction. The results indicated that RF (0.5 mM) promoted the VFAs production by up to 41.0%. Valeric acid accounted for the most abundance within the VFAs components. When RF dosages were 0.05 to 5.0 mM in the WAS fermentation systems, the chemical oxygen demand fractions of valeric acid to the total VFAs were 41.0% to 62.8%, which were much higher than those using other chemical supplements. Moreover, RF enhanced the reduction of mixed liquor volatile suspended solids (MLVSS). When RF dosage was 0.2 mM, MLVSS reduction achieved a maximum at 47.4%, compared to that in the RF-free control (33.9% reduction). Riboflavin in this study was considered as a feasible chemical to enhance the fermentative valeric acid generation coupled to MLVSS reduction, realizing the reduction of solids and the reutilization of valuable resources from WAS.

Anaerobic Co-digestion of Fruit and Vegetable Waste and Sewage Sludge

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Maria Cristina Rizk ◽  
Rosangela Bergamasco ◽  
Célia Regina Granhen Tavares
Keyword(s):  
Fatty Acids ◽  
Sewage Sludge ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Organic Load ◽  
Vegetable Waste ◽  
Fruit And Vegetable ◽  
The World ◽  
Vegetable Wastes

Fruit and vegetable wastes are generated in large quantities around the world. This kind of residue constitutes a source of nuisance in municipal landfills because of its high biodegradability. Another residue that is generated in large quantities around the world and also constitutes a source of nuisance is the sewage sludge. Both residues can be treated together by the anaerobic co-digestion process. In this sense, the aim of the present study was to evaluate the anaerobic co-digestion of fruit and vegetable waste and sewage sludge, in order to monitor the waste stabilization time and the biogas generation, among others. The study was conducted in a 70 litter stainless steel anaerobic reactor, with no mixing system, at room temperature (25±5ºC), during a period of 105 days. The fruit and vegetable wastes were collected in a central distribution market for food, and were shredded and blended before the experiment. The seed inoculum was collected in an anaerobic domestic sewage station of treatment. The parameters analyzed were: chemical oxygen demand, C/N and C/N/P ratios, pH, alkalinity, volatile fatty acids, and biogas generation. The results showed that the chemical oxygen demand was reduced around 20%. The parameters, pH, alkalinity and volatile fatty acids were stabilized, but the C/N wasn’t stabilized. The final value obtained for C/N ratio was around 20/1. The biogas generation was around 331 litters and most of the biogas production occurred during the first month of the experiment. The low chemical oxygen demand removal, the high C/N ratio and the biogas generation almost always in the first few days of the experiment probably indicate that this residue, although being organic, presents difficulties in its degradation, maybe because of the high organic load that was applied to the reactor. The fact of the reactor being disproved by a mixing system can also have contributed to the low residue degradation.

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.

scholarly journals Volatile Fatty Acids and Biomethane Recovery from Thickened Waste Activated Sludge: Hydrothermal Pretreatment’s Retention Time Impact

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1580
Author(s):  
Farokh laqa Kakar ◽  
Ahmed El Sayed ◽  
Neha Purohit ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Optimum Conditions ◽  
Pretreatment Temperature ◽  
Biomethane Production

The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.

scholarly journals Valorization of Glucose-Based Wastewater Through Production of Hydrogen, Volatile Fatty Acids and Alcohols

10.5772/67101 ◽  
2017 ◽  
Author(s):  
Eduardo Lucena Cavalcante de Amorim ◽  
Leandro Takano Sader ◽  
Lucas Rodrigues Ramos ◽  
Edson Luiz Silva
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Production Of Hydrogen ◽  
Fatty Acids And Alcohols

Saving phosphorus removal at the Henderson NV plant

2012 ◽  
Vol 65 (7) ◽  
pp. 1318-1322 ◽  
Author(s):  
J. Barnard ◽  
D. Houweling ◽  
H. Analla ◽  
M. Steichen
Keyword(s):  
Fatty Acids ◽  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
Biological Phosphorus Removal ◽  
Case Histories ◽  
Mixed Liquor ◽  
Removal Process ◽  
Low Levels ◽  
Anaerobic Zone ◽  
Biological Phosphorus

While the mechanism of biological phosphorus removal (BPR) and the need for volatile fatty acids (VFA) have been well researched and documented to the point where it is now possible to design a plant with a very reliable phosphorus removal process using formal flow sheets, BPR is still observed in a number of plants that have no designated anaerobic zone, which was considered essential for phosphorus removal. Some examples are given in this paper. A theory is proposed and then applied to solve problems with a shortage of VFA in the influent of the Henderson NV plant. Mixed liquor was fermented in the anaerobic zone, which resulted in phosphorus removal to very low levels. This paper will discuss some of the background, and some case histories and applications, and present a simple postulation as to the mechanism and efforts at modelling the results.

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