A review: factors affecting excess sludge anaerobic digestion for volatile fatty acids production

2015 ◽  
Vol 72 (5) ◽  
pp. 678-688 ◽  
Author(s):  
Dong Zhang ◽  
Xiaoshuai Li ◽  
Shuting Jia ◽  
Lingling Dai ◽  
Jianfu Zhao ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Optimal Operation ◽  
Excess Sludge ◽  
Treatment Methods ◽  
Factors Affecting ◽  
Time Control ◽  
Solids Retention ◽  
Pre Treatment

This paper presents a review of methods that improve the production of volatile fatty acids (VFA) from excess sludge during the anaerobic digestion process. These methods are mainly divided into two approaches. The first approach is located in the pre-treatment methods, which change the properties of the substrates, such as thermal pre-treatment, alkaline pre-treatment, microwave pre-treatment and ultrasonic pre-treatment. The other approach is found in the fermentation process control methods, which influence the environment of anaerobic digestion for the production of VFA, such as pH, temperature, mixing, additives and solids retention time control. In the text recent research studies of each method are listed and analyzed in detail. Comparably, microwave and ultrasonic pre-treatment methods are considered emerging and promising technologies due to their efficiency and environmentally friendly characteristics. However, the microwave pre-treatment has high electricity demand, which might make the process economically unfeasible. In order to calculate optimal operation, further studies still need to be done.

scholarly journals A review on strategies to optimize metabolic stages of anaerobic digestion of municipal solid wastes towards enhanced resources recovery

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Edwin N. Richard ◽  
Askwar Hilonga ◽  
Revocatus L. Machunda ◽  
Karoli N. Njau
Keyword(s):  
Fatty Acids ◽  
Trace Elements ◽  
Activated Carbon ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Solid Wastes ◽  
Municipal Solid Wastes ◽  
Ammonia Inhibition ◽  
Moisture Contents ◽  
Pre Treatment

AbstractRecently, there are increased efforts by municipals and researchers to investigate the potential of utilizing municipal solid wastes (MSW) for resources recovery. In many parts of developing countries, MSW is mostly collected for disposal with little emphasis on resources recovery. However, the MSW has high organic and moisture contents, and are suitable substrates for anaerobic digestion (AD) process to recover biogas for energy and digestate which can be used as fertilizers or for soil amendments. Resources recovery from the AD process consists of four metabolic stages; hydrolysis, acidogenesis, acetogenesis, and methanogenesis. These metabolic stages can be affected by several factors such as the nature of substrates, accumulation of volatile fatty acids, and ammonia inhibition. In this review, different optimization strategies towards resources recoveries such as pre-treatment, co-digestion, trace elements supplementation, optimization of key parameters and the use of granular activated carbon are discussed. The review reveals that the currently employed optimization strategies fall short in several ways and proposes the need for improvements.

Influence of hydrothermal pretreatment conditions, typology of anaerobic digestion system, and microbial profile in the production of volatile fatty acids from olive mill solid waste

2021 ◽  
Vol 9 (2) ◽  
pp. 105055
Author(s):  
Yasmim Arantes da Fonseca ◽  
Nayara Clarisse Soares Silva ◽  
Adonai Bruneli de Camargos ◽  
Silvana de Queiroz Silva ◽  
Hector Javier Luna Wandurraga ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Solid Waste ◽  
Volatile Fatty Acids ◽  
Hydrothermal Pretreatment ◽  
Microbial Profile ◽  
Olive Mill Solid Waste ◽  
Pretreatment Conditions ◽  
Olive Mill

Increasing 2 -Bio- (H2 and CH4) production from food waste by combining two-stage anaerobic digestion and electrodialysis for continuous volatile fatty acids removal

2021 ◽  
Vol 129 ◽  
pp. 20-25
Author(s):  
Gamal K. Hassan ◽  
Rhys Jon Jones ◽  
Jaime Massanet-Nicolau ◽  
Richard Dinsdale ◽  
M.M. Abo-Aly ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Two Stage ◽  
Ch4 Production

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.

Determination of soluble carbohydrates, lactic acid and volatile fatty acids in soils and biological media

1929 ◽  
Vol 19 (4) ◽  
pp. 649-655 ◽  
Author(s):  
V. Subrahmanyan
Keyword(s):  
Fatty Acids ◽  
Lactic Acid ◽  
Volatile Fatty Acids ◽  
Soluble Carbohydrates ◽  
Biological Media ◽  
Factors Affecting

Methods for extraction, concentration and determination of minute quantities of soluble carbohydrates, lactic acid and volatile fatty acids have been described. Different factors affecting the accuracy of the determinations have been studied and corrections, where necessary, have been suggested.

scholarly journals Control and estimation of anaerobic digestion processes using hydrogen and volatile fatty acids measurements

2018 ◽  
Vol 78 (10) ◽  
pp. 2027-2035 ◽  
Author(s):  
M. Sbarciog ◽  
G. Giovannini ◽  
R. Chamy ◽  
A. Vande Wouwer
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Hydrogen Concentration ◽  
Volatile Fatty Acids ◽  
Control Structure ◽  
Tight Control ◽  
Detailed Model ◽  
Control Scheme ◽  
Estimation And Control ◽  
And Control

Abstract The anaerobic digestion (AD) technology is widely used in the treatment of waste and wastewater. To ensure the treatment efficiency and to increase the production of biogas, which can be reused as a renewable energy source, a good understanding of the process and tight control are needed. This paper presents an estimation and control scheme, which can be successfully used in the operation of the AD process. The process is simulated by the ADM1 model, the most complex and detailed model developed so far to characterize AD. The controller and the observer, which provides estimates of the unmeasurable variables needed in the computation of the control law, are designed based on a simplified model developed in a previous work. Since it has been shown that hydrogen concentration is an accurate and fast indicator of process stability, it was chosen as controlled variable. Aside from the hydrogen concentration, the only measurement employed by the proposed control structure is the volatile fatty acids concentration. Simulation results prove the effectiveness of the proposed control structure.

scholarly journals Recent Approaches for the Production of High Value-Added Biofuels from Gelatinous Wastewater

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4936
Author(s):  
Ahmed Tawfik ◽  
Shou-Qing Ni ◽  
Hanem. M. Awad ◽  
Sherif Ismail ◽  
Vinay Kumar Tyagi ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Energy Recovery ◽  
Protein Concentration ◽  
Volatile Fatty Acids ◽  
Low Cost ◽  
Large Fraction ◽  
Value Added ◽  
Organic Loading Rate ◽  
Simultaneous Treatment ◽  
Factors Affecting

Gelatin production is the most industry polluting process where huge amounts of raw organic materials and chemicals (HCl, NaOH, Ca2+) are utilized in the manufacturing accompanied by voluminous quantities of end-pipe effluent. The gelatinous wastewater (GWW) contains a large fraction of protein and lipids with biodegradability (BOD/COD ratio) exceeding 0.6. Thus, it represents a promising low-cost substrate for the generation of biofuels, i.e., H2 and CH4, by the anaerobic digestion process. This review comprehensively describes the anaerobic technologies employed for simultaneous treatment and energy recovery from GWW. The emphasis was afforded on factors affecting the biofuels productivity from anaerobic digestion of GWW, i.e., protein concentration, organic loading rate (OLR), hydraulic retention time (HRT), the substrate to inoculum (S0/X0) ratio, type of mixed culture anaerobes, carbohydrates concentration, volatile fatty acids (VFAs), ammonia and alkalinity/VFA ratio, and reactor configurations. Economic values and future perspectives that require more attention are also outlined to facilitate further advancement and achieve practicality in this domain.

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