Oxidation-reduction potential (ORP) as a control parameter in a single-stage partial nitritation/anammox process treating reject water

Abstract

BACKGROUND: Redox potential value (or pE) can be used as a monitoring parameter for deammonification processes treating reject water. In this study its use as a control parameter was investigated. Experiments were carried out with a one-stage partial nitritation/anammox process in a 200 L moving bed biofilm reactor (MBBR) with 40% filled Kaldnes biofilm carriers. RESULTS:Tests on different combinations of nitrogen loads (1.8-3.3 gN m −2 d −1 ) and pE values (−1, 0, 1) revealed that process performance was stable and nitrogen removal efficiency >80% was achieved at all tested pE values except pE= − 1. A value close to pE=0 was the most suitable in terms of process performance at 25 ∘ C at all tested pE values. With a fixed redox potential value (pE=0) used in the system, the air supply adjusted automatically under different nitrogen loads and maintained a high nitrogen removal efficiency. Theoretical calculations showed that pE >0.15 (at pH=7) provides conditions for nitrite conversion into nitrate at 25 ∘ C. CONCLUSION: Redox control turned out to be a suitable control parameter for operation of a partial nitritation/anammox process. A redox value of 0 was a suitable value under different nitrogen loads in this pilot-scale study.

Assessment of Water Quality Using Chemometrics and Multivariate Statistics: A Case Study in Chaobai River Replenished by Reclaimed Water, North China

“…DO content was more than 5 mg/L except the one in November. Additionally, the oxidizing environment contributes to nitrification [78]. The decrease in November probably was due to low temperature and less aquatic plants [49,79].…”

“…The decrease in November probably was due to low temperature and less aquatic plants [49,79]. pH also played an important role in nitrogen transformation, and the double influences of pH and the redox environment could be evaluated by the pH-pE plot [78]. Therefore, samples of reclaimed water and river water were projected into Figure 10.…”

“…All samples were located around the NO3 − line, where the stable nitrogen form was nitrate (NO3 − , +5). High DO value of reclaimed water (7.33 ± 1.75) and river water (6.20 ± 2.47) showed the oxidizing water environment, which was beneficial for nitrate stable and nitrification [78,80].…”

Anammox and partial denitrification coupling: a review

“…123 The ORP provides reliable control operating parameters for the stable operation of the anammox and partial denitrication coupling process. 124 4.1.3 C/N and NO 2 À /NH 4 + . C/N is the key to start an anammox and partial denitrication coupling reactor, and it is also an important control parameter to maintain stable reactor operation and efficient nitrogen removal.…”

The Improvement of Pollutant Removal in the Ferric-Carbon Micro-Electrolysis Constructed Wetland by Partial Aeration

“…Though aeration was imported to strengthen the ammonia oxidation, excess aeration could inhibit the following denitrification process, which should be accurately adjusted. ORP, oxidation-reduction potential, reflects the concentration of oxidizing substance and the activity of organisms in the systems, which has also been used to monitor nitrification and denitrification processes [29]. In 0-10 cm, ORP declined in four systems because of the oxidation of Fe and NH 4 + -N by DO.…”