Simultaneous treatment and single cell protein production from agri-industrial wastewaters using purple phototrophic bacteria or microalgae – A comparison

Abstract

Resource recovery, preferably as high value products, is becoming an integral part of modern wastewater treatment, with conversion to heterotrophic or phototrophic/photosynthetic microbes a key option to minimise dissipation, and maximise recovery. This study compares the treatment capacities of purple phototrophic bacteria (PPB) and microalgae of five agri-industrial wastewaters (pork, poultry, red meat, dairy and sugar) to recover carbon, nitrogen, and phosphorous as a microbial product. The mediators have different advantages, with PPB offering moderate removals (up to 74% COD, 80% NH-N, 55% PO-P) but higher yields (>0.75 gCOD gCOD) and a more consistent, PPB dominated (>50%) product, with a higher crude protein product (>0.6 gCP gVSS). The microalgae tests achieved a better removal outcome (up to 91%COD, 91% NH-N, 73%PO-P), but with poorer quality product, and <30% abundance as algae.

Utilization of Vegetable Waste Juice by Purple Non-Sulfur Bacterium (&lt;i&gt;Afifella marina&lt;/i&gt; Strain ME) for Biomass Production

“…The possibility of insufficient nutrient in PVJ might be the cause of growth inhibition in which it requires to dilute the pure vegetable juice for satisfactory growth of bacteria. PNSB can utilize the wider range of nutrition that allows them to grow on virtually any organic materials and are efficient, dominant mediators for organic and nutrient removal from poultry, red meat, pork, and to a lesser extent, dairy and sugar wastewater [19]. Yeast extract is an important source of nitrogen and thiamine for the synthesis of amino acids and nucleic acids in bacterial cells [20].…”

Distributed parameter modelling of phototrophic bioreactor systems

“…In addition to the removal of wastes, there has been increased interest in the production of high value products by purple bacteria [30]. The pigments associated with purple phototrophic bacteria are high in protein, which can be used for either animal or possible human feed [31,32] or they can be used for pharmaceutical and cosmetic products [33]. They are resilient under favourable radiative conditions, quickly out-competing other non-photosynthetic organisms [34].…”

Photosynthetic biodegradation of domestic and agroindustrial wastewater

“…Indeed, these microorganisms are unique in their ability to employ all known modes of metabolism to assimilate carbon ( Figure 5) (Puyol et al, 2017). In addition to the obvious function of providing carbon for cell material construction, CO2 assimilation and organic carbon oxidation play a central role in maintaining the redox balance of PPB (Hunter et al, 2009).…”

“…The genes for nitrate assimilation are expressed when ammonia and other forms of fixed nitrogen are limiting and nitrate is available. PPB are also able to fix N2 (Hunter et al, 2009). The three main mechanism involved in nitrogen removal are reviewed in the following sections.…”

“…The ability to fix dinitrogen is found only among representatives of two of the primary kingdoms of living organisms: prokaryotic archaea and bacteria. The reduction of nitrogen gas to ammonium requires 8 electrons as shown in equation [11] ( Hunter et al, 2009).…”