Outdoor phycoremediation and biomass harvesting optimization of microalgae Botryococcus sp. cultivated in food processing wastewater using an enclosed photobioreactor.

Microalgae cultivation is well known as a sustainable method for eco-friendly wastewater phycoremediation and valuable biomass production. This study investigates the feasibility and kinetic removal of organic compounds and nutrients from food processing wastewater (FPW) using Botryococcus sp. in an enclosed photobioreactor. Simultaneously, response surface methodology (RSM) via face-centered central composite design (FCCCD) was applied to optimize the effects of alum and chitosan dosage and pH sensitivity on flocculation efficiency. The maximum growth rate of Botryococcus sp. cultivated in FPW was 1.83 mg day-1with the highest removal of chemical oxygen demand (COD), total organic carbon (TOC), and total phosphorus (TP) after 12 days of phycoremediation of 96.1%, 87.2%, and 35.4%, respectively. A second-order polynomial function fits well with the experimental results. Both coagulant dosage and pH significantly (p < 0.05) affect the flocculation efficiency of Botryococcus sp. biomass cultivated in FPW. The highest flocculation efficiency (92.4%) was obtained at a dosage of 166 mg L-1and pH 12 for alum coagulant, while 94.9% flocculation efficiency was achieved with optimum chitosan dosage and pH of 30 mg L-1and 5.54, respectively. In general, Botryococcus sp. shows a great removal efficiency of FPW contamination, whereas RSM provides excellent analysis for biomass harvesting optimization using a flocculation technique.

Eutrophication is caused by an overabundance of organic compounds and nutrients such as chemical oxygen demand, total nitrogen, phosphorus and total organic carbon in food processing wastewater (FPW) that is discharged into natural water systems. Although, there has been few research on the phycoremediation using Botryococcus sp. in wastewater treatment. Hence, the current study was carried out to investigate Botryoccocus sp. biomass harvesting efficiency using alum and chitosan as flocculants after the nutrients and organic compounds removal were analyzed during phycoremediation. The use of response surface methodology also offers excellent statistical analysis for flocculation optimization.

Emergence of nanomaterials as potential immobilization supports for whole cell biocatalysts and cell toxicity effects.

The traditional approach of fermentation by a free cell system has limitations of low productivity and product separation that need to be addressed for production enhancement and cost effectiveness. One of potential methods to solve the problems is cell immobilization. Microbial cell immobilization allows more efficient up-scaling by reducing the nonproductive growth phase, improving product yield and simplifying product separation. Furthermore, the emergence of nanomaterials such as carbon nanotubes, graphene, and metal-based nanomaterials with excellent functional properties provides novel supports for cell immobilization. Nanomaterials have catalytic properties that can provide specific binding site with targeted cells. However, the toxicity of nanomaterials towards cells has hampered its application as it affects the biological system of the cells, which cannot be neglected in any way. This gray area in immobilization is an important concern that needs to be addressed and understood by researchers. This review paper discusses an overview of nanomaterials used for cell immobilization with special focus on its toxicological challenges and how by understanding physicochemical properties of nanomaterials could influence the toxicity and biocompatibility of the cells.