Aerobic granular sludge (AGS) is an innovative biotechnology extensively applied for treating municipal wastewater, and it can potentially treat sugar industry wastewater. Glucose is a prevalent substrate in sugar industry wastewater; nevertheless, the effect of glucose on AGS systems remains unexplored. In this study, an AGS reactor using glucose as the sole carbon source was operated in anaerobic-aerobic cycles. The system maintained a solids retention time (SRT) of 10 days, resulting in good granulation and enhanced biological phosphorus removal (EBPR) performance. The glucose fed was rapidly taken up within 10 minutes, with a portion stored as intracellular polymers such as glycogen and poly-hydroxy-alkanoates (PHAs), while another portion underwent anaerobic fermentation to lactate and formate. The carbon balance was not completely closed, with 16% of the carbon speculated to be utilized for the production of an unidentified polymer. The microbial community consisted of diverse organisms, with Micropruina identified as the most abundant genera and Ca. Accumulibacter (a typical type of PAOs) as the second most abundant genera based on metagenomic analysis. A batch test was conducted by adding an excess of glucose, lactate, and formate, revealing that lactate was the probable substrate utilized by PAOs. Additionally, Micropruina was hypothesized to be involved in glucose consumption, glycogen storage, and lactate production. Micropruina and Ca. Accumulibacter collaborate in utilizing glucose, providing them with a significant competitive advantage within the system. Due to their slow growth rate, these bacteria play a crucial role in achieving favorable granulation when supplied with glucose. Promoting the growth of these organisms can be a valuable strategy in engineering applications.

Poly-hydroxy-alkanoate (PHA) is an intracellular polymer that can be used as an energy and carbon source by microorganisms. Measuring PHA is important for understanding the microbial metabolism of enhanced biological phosphorus removal (EBPR) and aerobic granular sludge (AGS) systems. There is a commonly used method to measure PHA, which is based on organic solvent extraction and gas chromatography (GC). However, there are different versions of the same method with different parameters, but the role of some of these parameters is unclear. When different types of biomass are analyzed, there is a requirement to understand the parameters and obtain an optimal protocol. In this study, the effect of various digestion times, different alcohols and organic solvents, and acid concentrations were tested to obtain the optimal protocol. The results showed that a minimum digestion time was required to get the maximum yield of PHA, and the time might differ when using different types of biomass. Methanol was shown to be better for GC separation than propanol. Using different organic solvents didn’t affect the final concentration, and an optimal acid concentration was required to determine by comparison. The GC temperature program optimization showed that lower oven temperature in GC is more beneficial for peak separation. From the analysis, it would be suggested to use methanol and chloroform for digestion and keep the digestion time for 24 hours.