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.

Evolution of adsorption process for manganese removal in water via agricultural waste adsorbents.

Manganese has recently been a topic of interest among researchers, particularly when 1,752 million tonnes of manganese are expected to be produced by the steel industry in 2020. Manganese discharges from industrial effluents have increased manganese contamination in water sources. Its concentrations of more than 0.2 mg/L in the water sources could have negative impacts on human health and the aquatic ecosystem. Thereby, the available water treatment processes face challenges in effectively removing manganese at low cost. In response to these challenges, adsorption has emerged as one of the most practical water treatment processes for manganese removal. In particular, agricultural waste adsorbents received a lot of attention owing to their low cost and high efficiency (99%) in the removal of manganese. Therefore, this paper reviews the removal of manganese by adsorption process using agricultural waste adsorbents. The factors affecting the adsorption process, the mechanisms, and the performances of the adsorbents are elucidated in detail.

Growth of microalgae Botryococcus sp. in domestic wastewater and application of statistical analysis for the optimization of flocculation using alum and chitosan.

Microalga biomass has been recognized as a sustainable bio-product to replace terrestrial biomass in biofuel production. The microalga industry has high operating costs, specifically on harvesting and biomass recovery. Therefore, the development of an efficient harvesting method is crucial to the minimization of production cost. A statistical analysis through response surface methodology was used to investigate the optimization of harvesting efficiency using alum and chitosan as a coagulant. Growth rate and biomass productivity were also determined. This research revealed that the harvesting efficiency using alum was 99.3%, with optimum dosage and pH of 177.74 mg L-1 and 8.24, respectively. Chitosan achieved 94.2% biomass recovery at an optimal dosage of 169.95 mg L-1 at pH of 12. Moreover, Botryococcus sp. achieved the maximum growth of 0.7551 µmax d-1, with an average total biomass productivity of 9.81 mg L-1 d-1 in domestic wastewater. Overall, this study shows that both alum and chitosan coagulants have great potential for efficient microalgal biomass recovery. It suggests that domestic wastewater as a potential growth medium for the large-scale production of microalga biomass.