The use of algae as a feedstock for biofuels production has drawn considerable attention due to their high biomass yield, their ability to be cultivated using degraded water on nonarable land, and their ability to recover nutrients from wastewater. Although algae have the potential to provide biomass for biofuels, some challenges remain and the limitations may be overcome by improving algal growth rates together with lipid synthesis. To achieve this, scientific researchers have focused on isolating and screening algal strains with better growth rates and lipid synthesis capabilities, bioengineering, and optimizing culture systems. The present review focuses on the biophotonic-based manipulations that can be applied to optimize solar-powered photobioreactors (PBRs).Hence, three different types of solar filters are reviewed herein, that is, the colored glass, thin-film, and thermochromic filters. This review provides evidence that bright red-colored glass filters can lower the spectral intensity of solar radiation from 1982.13 to 393.71 μmol m −2 s −1 , which is preferable for improved biomass productivity. Changing filter color, once the desired biomass concentration has been amassed, to medium blue or bright pink further improves lipid yield. A 34% improvement in biomass productivity was observed for Chlorella vulgaris cultured under thin-film filters. Thin-film filters are also effective in regulating PBR temperature within the 24-31 C range, which is tolerable for most algal species. Furthermore, this study highlights that the applicability of thermochromic filters in PBR designs is still yet to be investigated. Thermochromic filters are reflective and absorptive under high and low temperatures, respectively, a technology that can be a solution to the overheating challenge of PBRs. This review recommends the coupling of these light

Microalgae are increasingly being preferred as sustainable biomass feedstock for biofuels production due to their high growth rate and lipid yield. However, optimal production requires the use of economical native microalgal species which are well adapted to local climatic and ecological conditions. Therefore, this study's main objective was to isolate and select local microalgal species for prospective biofuels production. Serial dilution and streak plate techniques were used to isolate four species: Chlorella, Scenedesmus, Oscillatoria and Microcystis from Manyame River, Zimbabwe. The isolates were evaluated for their biomass and lipid productivity under artificial lighting (8:16 h light/dark cycle) and a temperature of 25 ± 3°C. Lipid quantification was done gravimetrically, using hexane as an extraction solvent. Each isolate's performance was compared against that of an imported Chlorella vulgaris strain. Amongst the isolates, Chlorella sp. exhibited a highly competitive growth rate of 0.26 d −1 and lipid yield of 37.16% dry cell weight. In comparison, the imported C. vulgaris had a growth rate of 0.226 d −1 and lipid yield of 35.74% dry cell weight. Although findings suggest that the native Chlorella sp. is the ideal candidate, growth enhancement and genetic engineering techniques may be used to further improve its biomass and lipid yield.

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Contamination of aquatic environments by pollutants of emerging concern (PEC) creates new public health and environmental threats. Over the years, Africa has struggled to adequately treat wastewater before discharged into the environment. The situation is expected to be worsened by the more challenging to treat PEC like pharmaceuticals, endocrine disrupters, microplastics, surfactants, cyanotoxins, radioactive and flame retardants. Generally, the pollution of aquatic environments will have serious negative impacts on organisms that depend on the affected sources. Elsewhere, a number of research studies have reported the occurrence of these pollutants and in some cases exceeding the recommended levels. However, in Africa and other developing countries, a few studies have focused on PEC in aquatic resources. In this review, discussions are centered on the: (i) occurrence of PEC in African aquatic environments, (ii) potential risks to aquatic ecosystems and human health, and (iii) current chemical and biological monitoring techniques. There is need to include PEC in the research studies and routine environmental monitoring programmes particularly before the urban wastewater is discharged into the environment. Passive biomonitoring through using biomarkers like oxidative stress proteins and gonadal histopathology may be more informative and cheaper way of monitoring PEC than chemical analysis.