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.

Nutrient and trace element supply in anaerobic digestion plants and effect of trace element application

2012 ◽  
Vol 66 (9) ◽  
pp. 1923-1929 ◽  
Author(s):  
H. Lindorfer ◽  
D. Ramhold ◽  
B. Frauz
Keyword(s):  
Fatty Acids ◽  
Trace Elements ◽  
Anaerobic Digestion ◽  
Chemical Composition ◽  
Trace Element ◽  
Volatile Fatty Acids ◽  
Bacterial Biomass ◽  
Substrate Feeding ◽  
Macro And Micronutrients ◽  
Process Disturbances

To investigate process behaviour and process disturbances in anaerobic digestion (AD) plants, samples of more than 1500 main digesters were taken and concentrations of macro- and micronutrients as well as volatile fatty acids were analyzed. Out of these samples, 600 digesters using energy crops only and 80 digesters using waste substrates were selected to compare the chemical composition as a result of different substrate feeding. High variations in element concentrations were found in both groups. In 60 plants with low micronutrient levels, trace elements were added and process changes were observed. A significant decrease of volatile fatty acids and an increase in digester performance were measured after trace element application. Furthermore, an increase of bacterial biomass could be detected.

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.

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.

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 Biodrying process: a sustainable technology for treatment of municipal solid wastes organic fraction

2018 ◽  
Author(s):  
Nabil Kechaou ◽  
E Ammar
Keyword(s):  
Organic Matter ◽  
Moisture Content ◽  
Energy Recovery ◽  
Pollution Source ◽  
Solid Wastes ◽  
Waste To Energy ◽  
Organic Fraction ◽  
Municipal Solid Wastes ◽  
Moisture Contents ◽  
Forced Aeration

The Municipal Solid Waste of Agareb (Sfax –Tunisia), characterized by high organic fraction and moisture contents is the most worrying pollution source that must be managed by innovative treatment and recycling technologies. Bio-drying, as a waste to energy conversion technology, aims at reducing moisture content of this organic matter. This concept,  similar to composting, is accomplished by using the heat generated from the microbial degradation of the waste matrix, while forced aeration is used. The purpose of this work was to reduce the moisture content of the waste, by maximizing drying and minimizing organic matter biodegradation, in order to produce a solid recovered fuel with high calorific value.Keywords: Municipal solid wastes; organic matter; biodrying; composting; energy recovery.

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