Anaerobic digestion of aerobic granular biomass: effects of thermal pre-treatment and addition of primary sludge

2013 ◽  
Vol 89 (5) ◽  
pp. 690-697 ◽  
Author(s):  
Ángeles Val Del Río ◽  
Tania Palmeiro-Sanchez ◽  
Mónica Figueroa ◽  
Anuska Mosquera-Corral ◽  
José L Campos ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Primary Sludge ◽  
Granular Biomass ◽  
Pre Treatment

scholarly journals Evaluation of acidogenic sludge from anaerobic reactors running at low solids retention times to reduce sludge generation and enhance biogas production

Water SA ◽  
2019 ◽  
Vol 45 (4 October) ◽  
Author(s):  
Wilza Da Silva Lopes ◽  
Ysa Helena Diniz Morais de Luna ◽  
Jose Tavares de Sousa ◽  
Wilton Silva Lopes ◽  
Valderi Duarte Leite
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Kinetic Constant ◽  
Oxygen Demand ◽  
Gas Production ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Solids Retention ◽  
Improved Performance ◽  
Pre Treatment

ABSTRACT   Sludges generated in the biological processing of sewage are complex mixtures, the constituents of which pose risks to public health and the environment. Anaerobic digestion is considered the most sustainable option for treating sludge because it offers the possibility of generating biogas. The aim of this study was to compare the quantities, properties, biodegradabilities and biochemical methane potentials (BMP) of primary sludge (PS) generated by a primary decanter with acidogenic sludges produced by upflow anaerobic (UA) reactors operating at solids retention times (SRTs) of 2, 4, 6 and 8 days (Samples S2, S4, S6 and S8, respectively). Sludges from both pre-treatments were submitted to alkaline solubilization in order to determine the efficiency of the process in disrupting extracellular complexes. Based on the levels of total solids (TS) present, the primary decanter was found to generate higher quantities of excess sludge (yield of 3.1 gTS∙d-1) than UA reactors operating at low SRTs (yields in the range 1.69 to 0.64 gTS∙d-1). The concentrations of dissolved materials in PS and Samples S2 and S8 were considerably higher after alkaline solubilization, with respective increases of 8, 14 and 28-fold in dissolved organic carbon, 12, 20 and 40-fold in chemical oxygen demand, 25, 31 and 59-fold in proteins, and 17, 21 and 63-fold in carbohydrates. In addition, the BMP value for S8 was some 13% higher than that recorded for PS while the kinetic constant for gas production by S8 was 1.8-fold greater than that of PS. It is concluded that a pre-treatment combining anaerobic digestion at low SRT and alkaline solubilisation would lead to improved performance in subsequent stages of anaerobic digestion and, consequently, increased efficiency in biogas production.

Thermal pre-treatment of primary and secondary sludge at 70 °°C prior to anaerobic digestion

2005 ◽  
Vol 52 (1-2) ◽  
pp. 161-166 ◽  
Author(s):  
I.V. Skiadas ◽  
H.N. Gavala ◽  
J. Lu ◽  
B.K. Ahring
Keyword(s):  
Organic Matter ◽  
Anaerobic Digestion ◽  
Low Cost ◽  
Methane Recovery ◽  
Primary Sludge ◽  
Thermophilic Anaerobic Digestion ◽  
Secondary Sludge ◽  
Thermophilic Digestion ◽  
Pre Treatment ◽  
Digestion Step

In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion, mainly because of the lower energy requirements and higher stability of the process. However, the thermophilic anaerobic digestion process is usually characterised by accelerated biochemical reactions and higher growth rate of microorganisms resulting in an increased methanogenic potential at lower hydraulic retention times. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization and could be realized at relatively low cost especially at low temperatures. The present study investigates the effect of the pre-treatment at 70 °C on thermophilic (55 °C) anaerobic digestion of primary and secondary sludge in continuously operated digesters. Thermal pre-treatment of primary and secondary sludge at 70 °C enhanced the removal of organic matter and the methane production during the subsequent anaerobic digestion step at 55 °C. It also greatly contributed to the destruction of pathogens present in primary sludge. Finally it results in enhanced microbial activities of the subsequent anaerobic step suggesting that the same efficiencies in organic matter removal and methane recovery could be obtained at lower HRTs.

Two combined techniques to enhance anaerobic digestion of sludge

2002 ◽  
Vol 46 (10) ◽  
pp. 167-172 ◽  
Author(s):  
G. Moeller-Chávez ◽  
S. González-Martínez
Keyword(s):  
Anaerobic Digestion ◽  
Yeast Extract ◽  
Methane Production ◽  
Influencing Factor ◽  
Removal Rates ◽  
Primary Sludge ◽  
Methanogenic Activity ◽  
Iron Nickel ◽  
Pre Treatment ◽  
Treatment Procedures

The rate-limiting step during anaerobic digestion is the hydrolysis of the particulate organic matter and methanogenesis. Certain elements, such as iron, nickel and cobalt and some growth factors such as coenzymes are needed for the adequate growth of the organisms. The main objective of this research was to enhance anaerobic digestion of primary sludge combining thermal and alkaline pre-treatment with stimulation of the methanogenic activity by adding yeast extract. Primary sludge was exposed, separately, to alkaline and thermal pre-treatment procedures. After this pre-treatment, different amounts of yeast extract were added to the sludge. The best COD, TSS and VSS removal rates were observed without pre-treatment and with the addition of 0.1% in weight of yeast extract. The highest specific methane production was obtained with thermal pre-treatment and 0.1% yeast addition. A second experimental stage was run for a closer analysis of the preliminary results. Thermal pre-treatment and 0.1% yeast addition was tested. The best results regarding both COD, TSS and VSS removal rates and methane production were obtained without thermal pre-treatment and with addition of yeast extract. The calculated F-values for the ANOVA-test show that the main influencing factor was the addition of yeast extract where the Biochemical Methane Production was doubled compared with the blank. The highest values for the hydrolysis constants were obtained at hydraulic retention times of six days after adding 0.1% of yeast extract.

Anaerobic Digestion of Primary Sludge Containing Iron Phosphate

1973 ◽  
Vol 8 (1) ◽  
pp. 91-109 ◽  
Author(s):  
M.E. Jack ◽  
G.J. Farquhar ◽  
G.M. Cornwall
Keyword(s):  
Anaerobic Digestion ◽  
Phosphorus Removal ◽  
Municipal Wastewater ◽  
Iron Phosphate ◽  
Chemical Precipitation ◽  
Task Group ◽  
Iron Compounds ◽  
Primary Sludge ◽  
Group Report ◽  
Aluminum Compounds

Abstract The importance of phosphorus as a nutrient in the eutrophication of lakes and rivers has been well established (Fruh 1967). It has been shown in addition that a significant amount of this phosphorus arises from the discharge of treated and untreated municipal wastewater (Task Group Report 1967). Consequently, measures are being taken, notably in the Province of Ontario, for removal of phosphorus from wastewater by means of chemical precipitation. Chemicals exhibiting satisfactory phosphorus removal include lime, iron compounds and aluminum compounds (Leckie and Stumm 1970; Schmid 1968; Wuhrman 1968).

scholarly journals Efficiency of integrated electrooxidation and anaerobic digestion of waste activated sludge

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
J. A. Barrios ◽  
A. Cano ◽  
F. F. Rivera ◽  
M. E. Cisneros ◽  
U. Durán
Keyword(s):  
Anaerobic Digestion ◽  
Current Density ◽  
Methane Production ◽  
Energy Recovery ◽  
Energy Analysis ◽  
Mathematical Optimization ◽  
Waste Activated Sludge ◽  
Bdd Electrode ◽  
Vs Removal ◽  
Pre Treatment

Abstract Background Most of the organic content of waste activated sludge (WAS) comprises microbial cells hard to degrade, which must be pre-treated for energy recovery by anaerobic digestion (AD). Electrooxidation pre-treatment (EOP) with boron-doped diamond (BDD) electrode have been considered a promising novel technology that increase hydrolysis rate, by the disintegrating cell walls from WAS. Although electrochemical oxidation could efficiently solubilize organic substances of macromolecules, limited reports are available on EOP of WAS for improving AD. In this endeavour, the mathematical optimization study and the energy analysis of the effects of initial total solids concentrations [TS] of WAS and current density (CD) during EOP on the methane production and removal of chemical oxygen demand (COD) and volatile solids (VS) were investigated. Because limited reports are available on EOP of WAS for improving biogas production, it is not well understood; however, it has started to attract interest of scientists and engineers. Results In the present work, the energy recovery as biogas and WAS conversion were comprehensively affected by CD and [TS], in an integrated EOP and AD system. When working with WAS at 3% of [TS] pre-treated at current density of 24.1 mA/cm2, the highest COD and VS removal were achieved, making it possible to obtain the maximum methane (CH4) production of 305 N-L/kg VS and a positive energy balance of 1.67 kWh/kg VS. Therefore, the current densities used in BDD electrode are adequate to produce the strong oxidant (hydroxyl radical, ·OH) on the electrode surface, allow the oxidation of organic compounds that favours the solubilization of particulate matter and VS from WAS. Conclusions The improvement of VS removal and COD solubilization were due to the effects of pre-treatments, which help to break down the microbial cells for faster subsequent degradation; this allows a decomposition reaction that leads to biodegrade more compounds during AD. The balance was positive, suggesting that even without any optimization the energy used as electricity could be recovered from the increased methane production. It is worth noting that this kind of analysis have not been sufficiently studied so far. It is therefore important to understand how operational parameters can influence the pre-treatment and AD performances. The current study highlights that the mathematical optimization and energy analysis can make the whole process more convenient and feasible.

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.

Sign in / Sign up

Export Citation Format

Share Document