Kulkarni PM. Effect of shock and mixed loading on the performance of SND based sequencing batch reactors (SBR) degrading nitrophenols.
WATER RESEARCH 2012;
46:2405-2414. [PMID:
22386885 DOI:
10.1016/j.watres.2012.02.008]
[Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 01/18/2012] [Accepted: 02/06/2012] [Indexed: 05/31/2023]
Abstract
The effect of nitrophenolic shock loads on the performance of three lab scale SBRs was studied using a synthetic feed. Nitrophenols were biotransformed by Simultaneous heterotrophic Nitrification and aerobic Denitrification (SND) using a specially designed single sludge biomass containing Thiosphaera pantotropha. Reactors R1, R2 and R3 were fed with 200mg/L concentration of 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,4,6-trinitrophenol (2,4,6-TNP) whereas reactor R was used as a background control. Three nitrophenolic shock loadings of 400, 600 and 800 mg/Ld were administrated by increasing the influent nitrophenolic concentration while keeping the hydraulic retention time as 48 h. The shocks were given continuously for a period of 4 days before switching back to normal nitrophenolic loading (200mg/Ld). The reactors were allowed to recover to normal performance level before administrating the next nitrophenolic shock load. The study showed that a nitrophenolic shock load, as high as 600 mg/Ld was completely degraded by the 4-NP & 2,4-DNP bioreactors while almost half degraded by the 2,4,6-TNP bioreactor without affecting the reactor's performance irreversibly. After resuming the normal nitrophenolic loading, it took almost 8-10 days for the reactors to recover from the shock effect. The study was further extended to evaluate the maximum possible mixed nitrophenolic loading (4-NP:2,4-DNP:2,4,6-TNP 1:1:1) to which a reactor (R3) containing 2,4,6-TNP acclimated single sludge biomass can be exposed without hampering the reactor performance irreversibly. The reactor was able to achieve pseudo-steady-state at a mixed nitrophenolic loading of 300 mg/Ld with more than 90% removal of all the three nitrophenols, but could remove half of the mixed nitrophenolic loading of 600 mg/Ld.
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