Ricerc@Sapienza

Polyhydroxyalkanoates (PHAs) production at pilot scale has been recently investigated
and carried out exploiting different process configurations and organic wastes. More in
detail, three pilot platforms, in Treviso (North-East of Italy), Carbonera (North-East of Italy)
and Lisbon, produced PHAs by open mixed microbial cultures (MMCs) and different
organic waste streams: organic fraction of municipal solid waste and sewage sludge
(OFMSW-WAS), cellulosic primary sludge (CPS), and fruit waste (FW), respectively.

The aim of this work is to give a practical example of a possible integration of organic waste management and wastewater treatment through a multi-step process for biowaste conversion into biopolymer, more specifically Polyhydroxyalkanoates (PHA). A further valorization of the overflows via anaerobic digestion is also proposed, but still at preliminary stage. Due to their thermoplastic properties and biodegradability, PHA are considered one of the most promising biopolymers to replace part of the synthetic materials.

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).

This study analyses the bacterial population dynamics of a mixed microbial community (MMC) selected in a pilot plant producing polyhydroxyalkanoate (PHA) from the fermentation of the organic fraction of urban waste (OFMSW) and sewage sludge (SS). 16S rRNA gene high-throughput sequencing revealed the occurrence of a variety of PHA accumulating bacteria that ensured a stable PHA production in an open system operating with real substrates and without temperature control.

Olive oil mill wastewaters (OMW) cause serious environmental pollution problems due to their high level of production and specific chemical characteristics. An innovative disposal treatment and simultaneous valorization technology consists of using OMW as a no-cost substrate for mixed microbial culture (MMC)-based polyhydroxyalkanoates (PHAs) production process. Here, an MMC multi-stage process was developed in which after acidogenic fermentation, OMW was subjected to a solid liquid separation step by centrifugation.