Ricerc@Sapienza

In this research Scenedesmus obliquus and Chlorella vulgaris growth was tested on digestate sludge obtained from the anaerobic co-digestion treatment of the organic fraction of municipal solid waste (OFMSW) together with waste activated sludge (WAS). Digestate was diluted 1:10 and tested in three batch experimental conditions: with no pre-treatments (noPT), after centrifugation (AC) and after filtration (AUF), in order to evaluate microalgae limiting growth factors. The best growth was obtained by C. vulgaris on digestate AC compared to S.

In this study, polyhydroxyalkanoates (PHAs) production integrated with the via-nitrite nitrogen removal from anaerobic reject water was investigated at pilot scale under long-term period.

This paper evaluates the effects of ultrasonication (US) applied, individually or in combination with a mechanical treatment, to the effluent of anaerobic digestion (AD) of lignocellulosic waste, on methane (CH4) production. US of the substrate downstream of AD is a relatively novel concept aimed at improving the degradation of recalcitrant components in order to enhance the overall energy efficiency of the process. US tests were carried out on real digestate samples at different energies (500−50,000 kJ/kg total solids (TS), corresponding to sonication densities of 0.08−0.45 W/ml).

Anaerobic digestion (AD) of organic waste, although widely practiced, may require suitable accompanying treatments to enhance the degradability of complex materials. Since these may require significant efforts in terms of energy and chemical demand, careful assessment of their overall environmental sustainability is mandatory to evaluate their full-scale feasibility. The study aims to represent the environmental profile of ultrasonication (US) applied as a post-treatment of anaerobic digestion of agro-industrial organic residues.

The effects of a mechanical process were determined on the solid fuel quality and anaerobic biodegradability of hazelnut and olive pruning. Both the feedstocks did not meet the specification for industrial and residential pellets given in the European Standard EN ISO 17225-2, because of too high ash and nitrogen content. The coarser products from processing were notable for the high reduction in both the ash and nitrogen content.

The effects of a mechanical pretreatment were determined on the methane yield of water hyacinth. The feedstock was pretreated using a two stages dry milling process and the experiments were performed at a mass flow rate of about 750 kg h -1 . Untreated and pretreated materials were both anaerobically digested in batch reactors under mesophilic conditions for 28 days. The cumulative biogas production from pretreated hyacinth exceeded 141.8 Nm 3 tr -1 of volatile solids, showing a +44.5% gain compared to the raw material.

The effects of an industrial scale, mechanical pretreatment were determined on the methane yield of Giant reed stems. The feedstock was pretreated using a two stages dry milling process and the experiments were performed for two different mass flow rates (600 and 900 kg h-1). Untreated and pretreated stems were both anaerobically digested in batch reactors under mesophilic conditions for 28 days. The cumulative biogas production from the pretreated materials exceeded 212 Nm3t-1of volatile solids, showing a 137% gain compared to the raw material.

The integrated-multistage process proposed herein is a practical example of a biorefinery platform in which the organic fraction of municipal solid waste (OFMSW) is used as valued source for polyhydroxyalkanoates (PHA) and biogas production. Technical and economical feasibilities of this approach have been demonstrated at pilot-scale, providing a possible upgrade to traditional biowaste management practices, presently based on anaerobic digestion (AD).

The updated Bioeconomy Strategy document “A sustainable bioeconomy for Europe: strengthening the connection between economy, society and the environment”, which was issued by the European Commission in October 2018, encourages the exploitation of organic wastes according to a pyramidal hierarchy in which the extraction of valuable biomolecules, which will be used as they are or as precursors of high-added-value compounds, is a priority in biofuel production.

A combined acidic fermentation and anaerobic digestion (AD) treatment has been developed on pilot scale for urban bio-waste conversion into volatile fatty acid (VFA) and biogas. The specific waste mixture was composed by the pre-treated organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS), both produced inside the Treviso (northeast Italy) municipality. The effect of temperature (37 °C and 55 °C) was investigated in both steps.