scholarly journals Effect of micro-aerobic process on improvement of anaerobic digestion sewage sludge treatment: flow cytometry and ATP assessment

RSC Advances ◽  
2020 ◽  
Vol 10 (59) ◽  
pp. 35718-35728
Author(s):  
Reza Barati rashvanlou ◽  
Abbas Rezaee ◽  
Mahdi Farzadkia ◽  
Mitra Gholami ◽  
Majid Kermani

Micro-aeration as a pretreatment method improves the efficiency of anaerobic digestion of municipal sewage sludge and consequently promotes the methane production.

2001 ◽  
Vol 44 (10) ◽  
pp. 163-169 ◽  
Author(s):  
T. Lendormi ◽  
C. Prévot ◽  
F. Doppenberg ◽  
M. Spérandio ◽  
H. Debellefontaine

Wet oxidation (WO) in subcritical conditions is a new alternative to usual routes for sewage sludge treatment that complies with environmental standards. This paper presents tests carried out using a batch reactor and continuous pilot and industrial units, treating municipal sewage sludge. The main products after oxidation are CO2, water, VFA and ammonia. The results highlight the considerable influence of the treatment temperature and of the type of sewage sludge which is treated. At temperatures around 240°C, VFA fraction present in WO supernatant is limited to 50% because of the presence of non-degraded fatty compounds and surfactants. Moreover, the COD reduction is limited to 70%. On the contrary, at 300°C, COD removal efficiencies greater than 80% are achieved without any catalyst addition and, in addition, only highly biodegradable compounds remain in the oxidised liquor. In order to treat the residual ammonia nitrogen by biological processes, it is therefore necessary to obtain a VFA fraction as high as possible for achieving denitrification and then to operate the WO process at high temperature and without catalyst addition.


2006 ◽  
Vol 53 (11) ◽  
pp. 221-226 ◽  
Author(s):  
M. Minamiyama ◽  
S. Ochi ◽  
Y. Suzuki

Many environmental problems caused by endocrine disruptors (EDs) have been reported. It is reported that EDs flow into sewage treatment plants, and it has been pointed out that these may be shifted from the wastewater treatment process to the sludge treatment process. Little is known about the fate of EDs accumulated in sewage sludge, so we carried out a study to clarify the fate of EDs in sewage sludge treatment processes, especially in an anaerobic digestion process. In this study, nonylphenol (NP) was selected as a target ED. Nonylphenol ethoxylates (NPnEO) or nonylphenoxy acetic acids (NPnEC), which were the precursor of NP, were added to an anaerobic digestion process, and mass balance was investigated. The following results were obtained from the anaerobic digestion experiments. (1) NP1EO was injected to an anaerobic digestion testing apparatus that was operated at a retention time of approximately 28 d and a temperature of 35 °C with thickened sludge sampled from an actual wastewater treatment plant. Approximately 40% of the injected NP1EO was converted to NP. (2) NP1EC was injected to an anaerobic digestion testing apparatus with thickened sludge. As a result, almost all injected NP1EC was converted to NP. When NP2EC was injected, NP2EC was not converted to NP until the 20th day.


1992 ◽  
Vol 26 (9-11) ◽  
pp. 2465-2468 ◽  
Author(s):  
K. Sugrue ◽  
G. Kiely ◽  
E. McKeogh

With up to 100 tonnes/day of municipal sewage sludge, the municipality of Cork County Council had a problem of disposal. Spreading on agricultural land was the most common method of disposal until the 1986 EC Directive 86/278/EEC imposed severe restrictions on such a method. For industry in the county, the method of disposal was sometimes landfilling, but more often disposal at sea. The Helsinki Agreement terminates sea disposal. An evaluation of treatment and disposal means identified anaerobic digestion as an alternative to land and sea disposal. After anaerobic digestion, the sludge is sufficiently sti ilised to spread on land. A pilot project using a 20m3 reactor was studied for one year, using a fixture of municipal sewage sludge, yeast from a citric acid industry and abattoir waste (including blood, paunch contents and sheep's offal). The results were impressive; input sludge of 10% dry matter was reduced to 2%; the COD reduction approached 90%; in the mesophylic temperature range, the sludge was stabilised after an HRT of 29 days. The sludge after anaerobic digestion satisfies the EC limits for landspreading.


Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 590
Author(s):  
Marcin Zieliński ◽  
Marcin Dębowski ◽  
Joanna Kazimierowicz

The present study aimed to determine the effect of a 17.6 mT static magnetic field (SMF) on the efficiency of anaerobic digestion (AD) of municipal sewage sludge (MSS). The SMF had a significant impact on methane (CH4) production efficiency, the levels of fermentation rate (ηFMSS) vs. removal rate (ηVS), and the structure of the anaerobic bacteria consortium, but it did not affect cumulative biogas production. The highest CH4 yield (431 ± 22 dm3CH4/kgVS) and the highest methane content in the biogas (66.1% ± 1.9%) were found in the variant in which the SMF exposure time was 144 min/day. This variant also produced the highest ηFMSS and ηVS values, reaching 73.8% ± 2.3% and ηVS 36.9% ± 1.6%, respectively. Longer anaerobic sludge retention time in the SMF area significantly decreased AD efficiency and caused a significant reduction in the number of methanogens in the anaerobic bacteria community. The lowest values were observed for SMF exposure time of 432 min/day, which produced only 54.8 ± 1.9% CH4 in the biogas. A pronounced reduction was recorded in the Archaea (ARC915) and Methanosaeta (MX825) populations in the anaerobic sludge, i.e., to 20% ± 11% and 6% ± 2%, respectively.


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