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: 4.49). 12/2010; 101(23):9006-11. DOI: 10.1016/j.biortech.2010.06.150
Source: PubMed


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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Available from: Rémy Gourdon, Jan 23, 2015
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    • "Screenings will readily digest anaerobically with methane yields of around 0.3 m 3 CH 4 /kg VS applied (Le Hyaric et al., 2010; Cadavid and Horan, 2012). Nevertheless, given its heterogeneity and high content of sanitary items, it is an unsuitable feedstock for conventional mesophilic anaerobic digestion (MAD), a process commonly used at wastewater treatment plants, where it would cause solids accumulation, stratification and foaming (Le Hyaric et al., 2010). "
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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 · 5.53 Impact Factor
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    • "A number of investigations into the technical operation of municipal WWTPs have been reported. These include studies of plants using the traditional influent–effluent method and assessments of factors such as treatment efficiency, effluent quality, solid wastes, air emissions, and biogas production using life cycle assessment (LCA) (Arhoun et al., 2013; Björklund et al., 2001; Cakira and Stenstrom, 2005; Czepiel et al., 1993; Hyaric et al., 2010; Kumar et al., 2012; Othman et al., 2013). A handful of them were focused on the influence of different types of biogas–sludge use on energy consumption or environmental impact (Houillon and Jolliet, 2005; Pasqualino et al., 2009; Lundin et al., 2000; Pöschl et al., 2010). "
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    ABSTRACT: Wastewater treatment systems are increasingly designed for the recovery of valuable chemicals and energy in addition to waste stream disposal. Herein, the life-cycle energy production and emissions mitigation of a typical domestic wastewater treatment system were assessed, in which different combinations of biogas use and sludge processing lines for industrial or household applications were considered. The results suggested that the reuse of biogas and sludge was so important in the system's overall energy balance and environmental performance that it may offset the cost in the plant's installation and operation. Combined heat and power and household utilization were two prior options for net energy production, provided an ideal power conversion efficiency and biogas production. The joint application of household biogas use and sludge nutrient processing achieved both high net energy production and significant environmental remediation across all impact categories, representing the optimal tradeoff for domestic wastewater treatment.
    Bioresource Technology 07/2013; 144C:296-303. DOI:10.1016/j.biortech.2013.06.128 · 4.49 Impact Factor
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