aerobic granules

granulation

tapioca processing wastewater

sequencing batch airlift reactor

organic substance removal

sequencing batch airlift reactor (SBAR) sequencing batch airlift reactor (SBAR)

Biological and chemical treatment

Wastewater engineering

This study evaluated performance and granule features of a sequencing batch airlift reactor (SBAR) to treat tapioca-processing wastewater. The effect of organic loading rate (OLR) on the stabilization of aerobic granules was also investigated by increasing the OLR gradually from 2.5 kgCOD/m³.day to 10 kgCOD/m³.day. The results indicated that clear boundary granules were formed after a two-week cultivation period. The aerobic granules’ average diameter increased according to rise in OLR and got a stable value of 2.5 mm at an OLR of 7.5 kgCOD/m³.day. The mature granules consisted of a dark core (anoxic) and yellow sludge surroundings (aerobic). The higher OLR led to forming granules of diameter 3-4 mm which were then broken due to substrate diffusion limitation. Aerobic granules could successfully treat organic substances, NH₄⁺-N, and phosphorus with high removal efficiencies of 93.9-96.3%, 79.7-82.6%, and 80-95%, respectively. We observed that the aerobic granular sludge has good settling ability with a sludge volume index (SVI) lower than 50 mL/g, and is able to withstand high OLR. The experimental findings created a new prospect for granulation and employment of aerobic granules to treat industrial wastewater.