Accelerating effect of hydroxylamine and hydrazine on nitrogen removal rate in moving bed biofilm reactor

Deciphering the evolution of the functional genes and microbial community of the combined partial nitritation-anammox process with nitrate build-up and its in situ restoration

“…In the rst period of in situ restoration stage from day 237 to 305, different dosages of NH 2 OH were added into the system obtaining the total concentrations of 5, 10 and 20 mgNH 2 OH L À1 in each SBR cycle (Fig. 2), which were close to the concentrations used by Zekker et al 11 and Kindaichi et al 23 No sludge was discharged for accelerating the enrichment of anammox microorganisms. The nitrate concentration decreased sharply to 106.9 mg L À1 on day 305, and the MRNN also declined to 13.12%, which was less than the normal value of 15% for the stable CPNA process.…”

“…8 To deal with the nitrate build-up problem and restore the nitrogen removal of the CPNA process, several countermeasures had been proposed in the previous papers, such as the re-inoculation, reduction of the air ow rate, using the intermittent aeration and introducing the hydrocyclone to remove the NOB-containing occular sludge, however, none of these methods were quite effective or time-efficient to solve the NOB overgrowth. 9 Based on the previous researches that dosing the hydroxylamine (NH 2 OH), an intermediate in both nitrica-tion and anammox, could not only promote the nitrite accumulation in the nitrifying system, 10 but also stimulate the anammox activity, 11 a novel in situ restoration strategy of combined NH 2 OH dosing and sludge retention time (SRT) control was developed in a lab-scale SBR, 9 through which the nitrate build-up problem could be overcome in the short term.…”

In-situ restoring nitrogen removal for the combined partial nitritation-anammox process deteriorated by nitrate build-up

“…During the first restoration section with NH 2 OH dosing and no sludge wasting, the growth rate of the anammox biomass was increased from 0.031 to 0.038 d −1 when the concentration of NH 2 OH dosed in the SBR was increased from 10 to 20 mgNH 2 OH L −1 in the SBR. These results confirmed that NH 2 OH could promote anammox bacteria growth and recover the anammox activity [17,29,30]. These growth rates of anammox bacteria were close to the results from the pilot and full-scale CPNA processes (0.025 and 0.045 d −1 ) reported by Joss et al [10], but still lower than the 0.06 d −1 (11 days of doubling time) reported in the lab and full-scale of single anammox processes [17,33].…”

“…In aerobic nitrifying granule system with DO > 5 mg L −1 , stable partial nitritation was successfully achieved at 10 mgN L −1 of NH 2 OH dosage [28]. Researches conducted with the anammox biomass also showed that NH 2 OH addition could stimulate the removals of ammonium and nitrite simultaneously, and recover the anammox activity [17,29,30]. Therefore, the authors supposed whether or not it was possible to develop an in-situ restoring strategy based on the NH 2 OH for the deteriorated CPNA process with high NOB population.…”

Assessment of bioremediation of aliphatic, aromatic, resin, and asphaltene fractions of oil-sludge-contaminated soil

“…This study focused on the bioremediation of various fractions such as aliphatics, aromatics, resins, and asphaltene of oil sludge in the soil. Oxygen, nutrients, and moisture which are essential components for well-biodegraded oil-contaminated soils (Braddock et al 1997;Dibble and Bartha 1979;Zekker et al 2012b) were considered in this study. Reduction of aliphatic and aromatic fractions was also analyzed.…”