Biorefinery of cellulosic primary sludge towards targeted Short Chain Fatty Acids, phosphorus and methane recovery

Abstract

Cellulose from used toilet paper is a major untapped resource embedded in municipal wastewater which recovery and valorization to valuable products can be optimized. Cellulosic primary sludge (CPS) can be separated by upstream dynamic sieving and anaerobically digested to recover methane as much as 4.02 m/capita·year. On the other hand, optimal acidogenic fermenting conditions of CPS allows the production of targeted short-chain fatty acids (SCFAs) as much as 2.92 kg COD/capita·year. Here propionate content can be more than 30% and can optimize the enhanced biological phosphorus removal (EBPR) processes or the higher valuable co-polymer of polyhydroxyalkanoates (PHAs). In this work, first a full set of batch assays were used at three different temperatures (37, 55 and 70 °C) and three different initial pH (8, 9 and 10) to identify the best conditions for optimizing both the total SCFAs and propionate content from CPS fermentation. Then, the optimal conditions were applied in long term to a Sequencing Batch Fermentation Reactor where the highest propionate production (100-120 mg COD/g TVS·d) was obtained at 37 °C and adjusting the feeding pH at 8. This was attributed to the higher hydrolysis efficiency of the cellulosic materials (up to 44%), which increased the selective growth of Propionibacterium acidopropionici in the fermentation broth up to 34%. At the same time, around 88% of the phosphorus released during the acidogenic fermentation was recovered as much as 0.15 kg of struvite per capita·year. Finally, the potential market value was preliminary estimated for the recovered materials that can triple over the conventional scenario of biogas recovery in existing municipal wastewater treatment plants.

Validated innovative approaches for energy-efficient resource recovery and re-use from municipal wastewater: From anaerobic treatment systems to a biorefinery concept

“…For instance, acetate and butyrate are preferred for polyhydroxybutyrate (PHB) production, while propionate is required when producing polyhydroxyvalerate (PHV) (Shen et al 2014;Peces et al 2016). In addition, some important characteristics such as higher flexibility, low stiffness and brittleness, and higher tensile strength and toughness are highlighted to promote the production of co-polymers using VFAs with higher propionate/acetate ratio (Frison et al 2015;Crutchik et al 2018). However, establishing consistence VFA concentrations and proportion remains a significant challenge.…”

“…biodegradation of cellulose is comparatively difficult and depends on many factors (Ruiken et al 2013;Crutchik et al 2018). On the other hand, cellulose fibres hold a great potential as a resource which can be recovered from wastewater by sieving (Ruiken et al 2013).…”

“…The CPS can then be anaerobically digested to produce biogas, or, under optimal acidogenic fermenting conditions it produces VFAs. Here the propionate content can be more than 30% and can optimize the enhanced biological phosphorus removal (BPR) processes (Crutchik et al 2018). Long-term operation indicated that anaerobic alkaline fermentation for VFA production from sewage sludge is both technically and economically feasible (Liu et al, 2018).…”

Sistematska Analiza Mogucnosti Tretmana I Procena Količina Otpadnog Mulja Iz Komunalnih Otpadnih Voda

“…Kristalizacija je postupak koji se koristi za povraćaj fosfora iz PPOV u obliku struvita (NH 4 MgPO4). U istraživanju [10], pozivajući se na komunalnu otpadnu vodu sa TSS od 26 -30 kg/ES/god. i tečnu frakciju iz primerne fermentacije celuloidnog mulja, procenjeno je da se može proizvesti 0,07 -0,15 kg/ES/god.…”

Intensification of Short Chain Fatty Acid Production during the Alkaline Pretreatment of Fine-Sieving Fractions

“…In this sense, the maximum recovery of organics in raw sewage has become a research hotspot [11][12][13], with specific attention on fine-sieving utilization, for instance. Ruiken recovered the particulates via a fine sieve <350 µm with an average removal efficiency of 35% of the total COD [12].…”