Microalgae are well known for their ability to accumulate lipids intracellularly, which can be used for biofuels and mitigate CO emissions. However, due to economic challenges, microalgae bioprocesses have maneuvered towards the simultaneous production of food, feed, fuel, and various high-value chemicals in a biorefinery concept. On-line and in-line monitoring of macromolecules such as lipids, proteins, carbohydrates, and high-value pigments will be more critical to maintain product quality and consistency for downstream processing in a biorefinery to maintain and valorize these markets. The main contribution of this review is to present current and prospective advances of on-line and in-line process analytical technology (PAT), with high-selectivity - the capability of monitoring several analytes simultaneously - in the interest of improving product quality, productivity, and process automation of a microalgal biorefinery. The high-selectivity PAT under consideration are mid-infrared (MIR), near-infrared (NIR), and Raman vibrational spectroscopies. The current review contains a critical assessment of these technologies in the context of recent advances in software and hardware in order to move microalgae production towards process automation through multivariate process control (MVPC) and software sensors trained on "big data". The paper will also include a comprehensive overview of off-line implementations of vibrational spectroscopy in microalgal research as it pertains to spectral interpretation and process automation to aid and motivate development.
Ponds are probably the most common technology used for treatment of municipal, agricultural, and aquacultural wastewaters in the US. Compared to mechanical treatment technologies, ponds remove oxygen demand and suspended solids with low cost and energy consumption. However, nutrient removal is an increasingly common regulatory requirement, and conventional ponds are not well suited for nitrogen and phosphorus removal. Newer pond technologies (e.g., paddle wheel-mixed high rate ponds and newer variants of aerated lagoons) have advanced the reliability, effectiveness, and geographical range of pond treatment. This paper reports on results of pilot studies that have the goal of developing operational methods for high rate ponds (HRPs) that will allow them to consistently meet typical total suspended solids (TSS) secondary treatment discharge limits through bioflocculation, without chemical coagulants, and to allow them to remove nutrients to meet concentration or mass load discharge limits. The research was conducted in model 5-m 2 (50-ft 2 ) HRP tanks fed municipal wastewater. Unlike other Cal Poly HRP studies in which the ponds are operated at a 30-cm depth (1 ft) to optimize solar exposure of the algal cells and sparged with CO 2 to balance carbon:nutrient ratios, the present studies were conducted in 68-cm deep ponds without CO 2 addition, to better mimic existing full-scale wastewater treatment HRPs. Hydraulic residence times of 3 to 5 days were tested, and nighttime aeration was provided to some ponds. The studies demonstrated the ability to maintain bioflocculated algal cultures, with settling of algal biomass to achieve typical effluent discharge limits for pond suspended solids (40-60 mg/L). Total ammonia nitrogen removal during summer was >90%, and during winter it averaged 73%. Soluble carbonaceous BOD 5 was <10 mg/L, and total BOD 5 after effluent settling was <50 mg/L. These results are promising steps towards developing a low-cost, energy-efficient pond technology that, in suitable climates, can meet modern discharge standards.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.