EGSB reactor;  glucose wastewater;  influent concentration;  Sludge granulation

Anaerobic expansion granular sludge bed (EGSB) was used to treat glucose wastewater to study the effect of influent COD concentration on sludge granulation. The experimental results show that as the COD concentration of the influent water increases from 2 000 mg/L to 10 000 mg/L, the amount of nutrients entering the particles during mass transfer gradually increases, which promotes the granulation of sludge and increases the particle diameter. The drastic change of the influent concentration has a great impact on the reactor, causing excessive bacterial growth, loose sludge structure, decreased sedimentation performance, and reduced COD removal rate and gas production rate.