Pilot-scale anaerobic digestion of screenings from wastewater treatment plants

University of Lyon, INSA of Lyon, Lab. LGCIE, 20 av. A. Einstein, F-69621 Villeurbanne cedex, France.
Bioresource Technology (Impact Factor: 5.04). 12/2010; 101(23):9006-11. DOI: 10.1016/j.biortech.2010.06.150
Source: PubMed

ABSTRACT The anaerobic digestion of screenings from a municipal wastewater treatment plant was studied in a 90 L pilot-scale digester operated at 35 degrees C under semi-continuous conditions. In the first 4 weeks, a dry solids residence time of 28 days was applied, but the installation of inhibitory conditions was observed. Feeding was therefore suspended for 4 weeks to allow the digester to recover from inhibition, and then progressively increased up to a constant load of 6 kg of raw waste per week, corresponding to an average residence time of about 35 days of dry solids. At this stage, biogas production stabilized between 513 and 618 Nl/kg VS(added) per week, with methane contents around 61% v/v. The results of this work thereby supported the feasibility of (co-)digestion as a potential alternative treatment of screenings from municipal wastewater treatment plants.

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    ABSTRACT: Screenings recovered from the inlet works of wastewater treatment plants were digested without pre-treatment or dilution using a lab-scale, leach-bed reactor. Variations in recirculation ratio of the leachate of 4 and 8 l/lreactor/day and pH values of 5 and 6 were evaluated in order to determine the optimal operating conditions for maximum total volatile fatty acids (VFA) production. By increasing the recirculation ratio of the leachate from 4 to 8 l/lreactor/day it was possible to increase VFA production (11%) and soluble COD (17%) and thus generate up to 264 g VFA/kg-dry screenings. These VFA were predominantly acetic acid with some propionic and butyric acid. The optimum pH for VFA production was 6.0, when the methanogenic phase was inhibited. Below pH 5.0, acid-producing fermentation was inhibited and some alcohols were produced. Ammonia release during the hydrolysis of screenings provided adequate alkalinity; consequently, a digestion process without pH adjustment could be recommended. The leach-bed reactor was able to achieve rapid rates of screenings degradation with the production of valuable end-products that will reduce the carbon footprint associated with current screenings disposal techniques.
    Water Research 05/2014; 60C:242-249. DOI:10.1016/j.watres.2014.05.001 · 5.32 Impact Factor
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    ABSTRACT: Anaerobic digestion is one of the oldest and preferred processes for the stabilization of waste-activated sludge produced from treating urban and industrial wastewater. Although there is no clear agreement on when to clean the anaerobic digester tanks, regular cleaning has proved to enhance the efficiency of the system, to reduce mechanical problems, and to avoid a decrease in their useful volumes. This paper describes the use of the hydrocyclone technology as an alternative for desludging. The coarse fraction recovered before the hydrocyclone plant contained potentially biodegradable matter that could be used as soil amendment, with low concentrations of heavy metals. This fraction had the highest mass loss in the thermogravimetric analysis (78%), thus showing the presence of calcium stearate as the major component. This was further demonstrated by Fourier transform infrared spectroscopy analysis. The hydrocyclone system showed time-dependent separation ability for all types of solids, with concentration factors that were higher for fixed (12 ± 1 g/g) than for total (6 ± 1 g/g) or volatile (2 ± 1 g/g) solids, being always higher for the warm than for the cold season. The X-ray diffraction analysis showed the presence of quartz in fine and underflow fractions. The formation of struvite was observed with the increase in phosphorus and magnesium especially in the fine fraction, with higher levels of chromium than the influent sludge, albeit without ever exceeding the maximum limited values admitted by most European countries.
    Journal of Cleaner Production 01/2015; 87:550-557. DOI:10.1016/j.jclepro.2014.10.064 · 3.59 Impact Factor
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    ABSTRACT: Being utilized to produce biogas in anaerobic sludge digestion reactors in wastewater treatment facilities, sludge can also be defined as a carbon neutral biomass and is an effective resource that can be used in preventing global warming. On the other hand, hydrogen production from sludge is a highly noteworthy topic due to hydrogen’s quality of being the clean energy carrier of tomorrow and its production can be achieved through the fermentation of sludge. In this chapter, biogas and hydrogen production potentials of the municipal wastewater treatment facilities in Turkey are evaluated on the basis of sludge generation, and the impact of the developed hydrogen production models on global warming is set forth.
    Causes, Impacts and Solutions to Global Warming, 09/2013: chapter Assessment of Sewage Sludge Potential from Municipal Wastewater Treatment Plants for Sustainable Biogas and Hydrogen Productions in Turkey; Springer.


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Jan 23, 2015