[Effect of Influent Ammonia Concentration on a Biological Phosphorus Removal Granules System].

Mature biological phosphorus removal granules were inoculated into a SBR. The effect of the ammonia concentration on biological phosphorus removal granules system was investigated by increasing the concentration of ammonia in the influent. The ability of the system to withstand ammonia loading was determined. The results showed that when the influent ammonia concentration was below 45 mg·L-1, the biological phosphorus removal granule system showed good performance. The TP removal efficiency was above 96%, the COD removal efficiency was over 89%. The effluent TP concentration and COD concentration were 0.4 mg·L-1 and 25 mg·L-1 respectively. The particle size was above 950 µm and the SVI was below 45 mL·g-1. When the influent ammonia concentration was 60 mg·L-1, the removal efficiency of TP was more than 95%. The effluent TP concentration was below 0.5 mg·L-1, the particle size was 760 µm, and the SVI was 56 mL·g-1. Furthermore, the biological phosphorus removal granules partially disintegrated and the metabolism and growth of PAOs began to be inhibited in the system. When the influent ammonia concentration reached 70 mg·L-1, the removal efficiency of TP was 70%, the effluent TP concentration was about 3 mg·L-1, the particle size was 570 µm, the SVI was 75 mL·g-1, and the value of PN/PS was about 7.50. The biological phosphorus granules severely disintegrated and the metabolism and growth of PAOs was severely inhibited in the system. Moreover, as the influent ammonia concentration increased, the protein increased and polysaccharide decreased from the microbial secretion of biological phosphorus removal granules. Moreover, the value of PN/PS increased, the biological phosphorus removal granules disintegrated, the particle size decreased, the SVI increased, and the structure and function of the biological phosphorus removal granules were destroyed.

[COD Requirement for Biological Phosphorus Removal Granule System Under Different Phosphorus Concentrations].

In this study, the effect of COD loading on a biological phosphorus removal granule system under different phosphorus concentrations was investigated by changing the concentration of total phosphorus (TP) and COD in the influent. The lowest concentration of COD for good performance of the biological phosphorus removal system under different phosphorus concentrations was obtained. The results show that when the concentration of TP was 10 mg·L-1 in the influent, the lowest concentration of COD for good performance of the biological phosphorus removal system was 175 mg·L-1. The concentration of TP in the effluent was below 0.5 mg·L-1; the particle size and SVI were 1020 µm and 36 mL·g-1, respectively; and the contents of PN and PS (by MLSS) were 78 mg·g-1 and 39 mg·g-1, respectively. Furthermore, the PN/PS was lower and the granules had good structure and performance. When the concentration of TP was 6 mg·L-1 in the influent, the lowest concentration of COD for good performance of the biological phosphorus removal system was 150 mg·L-1. The concentration of TP in the effluent was below 0.3 mg·L-1; the particle size and SVI were respectively 960 µm and 35 mL·g-1; and the contents of PN and PS were 75 mg·g-1 and 35 mg·g-1, respectively. Moreover, the PN/PS was lower and the granules had good structure and performance. The removal efficiency of COD was above 83% and the concentration of COD in the effluent was below 25 mg·L-1 throughout the operational process. Under different the influent phosphorus concentrations, the contents of PN and PS decreased, PN/PS increased, particle size decreased, SVI increased, and the structure and performance of the biological phosphorus removal granules deteriorated as the COD concentration decreased.

[Effect of Aerobic/Phosphorus Granules on Start-up of Partial Nitrification Granular Sludge].

The different effects of additional aerobic granules (AGs) and phosphorus removal granules (PRGs) on the start-up and stable operation of partial nitrification granular sludge (PNGS) were compared at room temperature(22-28℃). The results showed that in the first stage (days 0-22), partial nitrification was accomplished on day 19 for the three reactors (R1, R2, and R3). In the second stage (days 23-56), 20% AGs and 20% PRGs were added to R2 and R3 to induce PNGS. The start-up of the granules of the three reactors was successfully achieved. The mean particle sizes of R1, R2, and R3 reached 412 µm at day 76, 468 µm at day 42, and 400 µm at day 56. In the third stage (days 57-108), because the influent ammonia load increased from 0.4 kg·(m3·d)-1 to 0.5 kg·(m3·d)-1 and the COD load increased from 0.2 kg·(m3·d)-1 to 0.5 kg·(m3·d)-1, the mean particle sizes of R1 and R2 increased significantly. The average particle sizes of R1 and R2 reached 689 µm and 893 µm by the end of the operation (day 108), but sludge expansion occurred in R3. The inoculation of either AGs or PRGs could quickly achieve granulation, but the PNGS inoculated with the AGs could adapt to higher C/N and be more tolerable to shock loads and long-term stable operation.