scholarly journals Nitrogen in the Process of Waste Activated Sludge Anaerobic Digestion

2014 ◽  
Vol 40 (2) ◽  
pp. 123-136 ◽  
Author(s):  
Jan Suschka ◽  
Klaudiusz Grübel

Abstract Primary or secondary sewage sludge in medium and large WWTP are most often processed by anaerobic digestion, as a method of conditioning, sludge quantity minimization and biogas production. With the aim to achieve the best results of sludge processing several modifications of technologies were suggested, investigated and introduced in the full technical scale. Various sludge pretreatment technologies before anaerobic treatment have been widely investigated and partially introduced. Obviously, there are always some limitations and some negative side effects. Selected aspects have been presented and discussed. The problem of nitrogen has been highlighted on the basis of the carried out investigations. The single and two step - mesophilic and thermophilic - anaerobic waste activated sludge digestion processes, preceded by preliminary hydrolysis were investigated. The aim of lab-scale experiments was pre-treatment of the sludge by means of low intensive alkaline and hydrodynamic disintegration. Depending on the pretreatment technologies and the digestion temperature large ammonia concentrations, up to 1800 mg NH4/dm3 have been measured. Return of the sludge liquor to the main sewage treatment line means additional nitrogen removal costs. Possible solutions are discussed.


2002 ◽  
Vol 46 (10) ◽  
pp. 173-179 ◽  
Author(s):  
S. Tanaka ◽  
K. Kamiyama

Effects of a thermochemical pretreatment on the anaerobic digestion of waste activated sludge (WAS) was investigated by semicontinuously-fed digesters operated at 37¡C. WAS from a return sludge line of a municipal sewage treatment plant was pretreated by autoclaving at 130°C for 5 minutes after adding 0.3g NaOH/g VSS. Solids of WAS were thermochemically solubilized to one half and then 60% or more were in totality solubilized in anaerobic digesters fed with pretreated WAS at 2-8 days of hydraulic retention times (HRT), while only 16-36% were solubilized in digesters fed with raw WAS. The adverse effect of the set temperature (130°C) on the biodegradability of protein was not found. As a result, removal rates of COD in digestion was increased from 38% to 57% at 8 days HRT by the pretreatment. A specific methane production rate in the pretreated process was three times as high as the normal process. The thermochemical pretreatment was found to be very effective to enhance biodegradability as well as solubilization of WAS in anaerobic digestion.





2013 ◽  
Vol 20 (1) ◽  
pp. 587-594 ◽  
Author(s):  
Serkan Şahinkaya ◽  
Mehmet Faik Sevimli


2014 ◽  
Vol 52 ◽  
pp. 242-250 ◽  
Author(s):  
Yinghong Feng ◽  
Yaobin Zhang ◽  
Xie Quan ◽  
Suo Chen


2021 ◽  
Author(s):  
Suleman Khan

The effects of hydrothermal pre-treatment on the production of methane and biogas on thickened waste activated sludge was investigated. This paper reviews the anaerobic digestion process and its complexities, provides an overview of the different stages of the anaerobic digestion process, different kinds of feedstocks and the essential and influential operating parameters such as temperature, pH, organic loading rate, solid retention time and particle size. This paper also demonstrates an overview of the natural and anthropogenic sources contributing to methane in the atmosphere. It further provides a recommendation on essential practices and methods required to enhance methane capture in the atmosphere. Furthermore, an experimental setup consisting of batch anaerobic digestion was employed for the sample analysis the purpose of this experimental research was to conduct a comprehensive assessment of the effect of the hydrothermal pre-treatment on thickened waste activated sludge and to determine the most optimum conditions to produce methane. Keywords: Anaerobic digestion, Thickened waste-activated sludge, Hydrothermal Pre-treatment



The increased demand for advanced techniques in anaerobic digestion over the last few years has led to the employment of various pre-treatment methods prior to anaerobic digestion to increase gas production. These pre-treatment methods alter the physical and chemical properties of sludge in order to make it more readily degradable by anaerobic digestion. Although the thermal pre-treatment presents high energy consumption, the main part of this energy to heat can be recovered from the biogas produced in the anaerobic process. In this research a mixture of primary and waste activated sludge was thermally pretreated at 100, 125, 150, 175 and 200 oC in order to determine the reaction kinetics for the increase of soluble organic fraction (expressed as CODs and VFAs). Experimental results proved that the solubilization of sludge is a 1st order reaction with respect to both CODs and VFAs, KCODs (reaction rate constant of CODs solubilization) increased from 4.59*10-3 (min-1) to 7.55*10-3 (min-1) as the temperature increased from 100 to 200 oC, with a reaction activation energy of 7447.21 (J/mole) and frequency factor of 0.051 (min-1), While KVFAs (reaction rate constant of VFAs solubilization) increased from 5.33*10-3 (min-1) to 7.97*10-3 (min-1) for the same increase in temperature, with a reaction activation energy of 5947.22 (J/mole) and frequency factor of 0.0364 (min-1).



Author(s):  
Aparna Garg ◽  
H. David Stensel ◽  
Bob Bucher ◽  
Pardi Sukapanpotharam ◽  
Mari K. H. Winkler


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