Effectiveness of oxidation-reduction potential and pH as monitoring and control parameters for nitrogen removal in swine wastewater treatment by sequencing batch reactors

Abstract

Two bench-scale sequencing batch reactors (SBRs) were operated in a fixed hydraulic retention time study to investigate the effectiveness of oxidation-reduction potential (ORP), pH and dissolved oxygen as parameters for indicating denitrification followed by nitrification in SBRs for swine wastewater treatment. The ORP and pH profiles were monitored and evaluated under different denitrification and nitrification conditions with and without a supplemental carbon source. With a low C/N ratio, and using a suitable C/N ratio adjustment control, ORP and pH could be used as monitoring and control parameters in both the anoxic and oxic phases for practical swine wastewater treatment. High-level accumulation of nitrate was observed without any C/N ratio adjustment. In this case, ORP and pH were not useful for monitoring denitriiication followed by nitrillcation in SBRs. According to our research, with regard to N removal, it would be better to use pH as a parameter during the oxic phase and ORP as a parameter during the anoxic phase. Using a suitable adjustment of a C/N ratio in the influent by adding swine slurry, a high total nitrogen removal efficiency of up to 95.5% was reached. It was found that, in this case, the use of ORP and pH as parameters for real-time control processes was possible in swine wastewater treatment.[Key words: oxidation-reduction potential (ORP), pH, real-time control, sequencing batch reactor (SBR), nitrogen removal, swine wastewater] Animal manure is widely used as a fertilizer in many countries, since animal waste contains nutrients such as nitrogen and phosphorus (1, 2). While land application of swine manure may be an economical and easy method to manage waste, this treatment causes many environmental problems such as contamination of groundwater and eutrophication of surface waters (3). In addition, with the present trend toward raising large herds of livestock in smaller areas, it is becoming difficult to apply all of the waste to cropland (4). Therefore, it is necessary to develop an alternative cost-effective waste treatment system and an enhanced treatment system for nutrient removal.In recent years, real-time control processes using oxidation-reduction potential (ORP), pH and dissolved oxygen (DO) as parameters to control the oxic and anoxic cycles of sequencing batch reactor (SBR) systems, have received much attention (5-9). Many researchers have shown that the ORP and pH pattern in a given wastewater treatment process can be used successfully to identify specific control points. In particular, in biological nitrogen removal proc-* Corresponding author. e-mail: j-kim@kankyou.pref.saitama.jp phone: +81-(0)480-73-8369 fax: +81-(0)480-70-2031 esses, several investigators have identified the "nitrate knee" in ORP profiles and the "nitrate apex*' in pH profiles which indicate the end of denitrification (5, 6), and the "nitrogen break point" or the "DO elbow" in ORP profiles and the "ammonia valley" in pH profiles, which indicate the end of nitrification (7-9). According to these control ...

Reactores discontinuos secuenciales: Una tecnología versátil en el tratamiento de aguas residuales.

“…Para optimizar el desempeño y mejorar el control del proceso se deben implementar estrategias de control y realizar mediciones de parámetros en tiempo real. Algunos de los más utilizados son el potencial de oxidoreducción (ORP, por sus siglas en inglés), pH y el oxígeno disuelto (OD) [22][23].…”

Water Quality Dynamic Monitoring Technology and Application Based on Ion Selective Electrodes

“…When the ORP is positive, it means that the oxidation ability of water body is strong, that is the ability of the recursive organism which handles the biological metabolism is strong. If the pH, DO and temperature are suitable, the pollutants in the water will be decomposed fast and effectively [28] . The principle of ORP measurement is similar with the measuring of pH, which based on the selectivity of H + by glass electrode, while the principle of ORP measurement refers to the electrons' acceptance or release of noble metal electrode.…”

Foaming control by automatic carbon source adjustment using an ORP profile in sequencing batch reactors for enhanced nitrogen removal in swine wastewater treatment

“…Run A1 was operated using a suitable organic load and C/N ratio (approximately 3.1 of BOD 5: TN), while runs A2, B1 and B2 were operated using a low C/N ratio (average BOD/ TN ratio between 1.3 and 1.8) in the influent. The reactor was constructed of Plexiglas and had a working volume of 9 L, as described in our previous papers [21,22]. The reactors had the following five sequences ( Fig.…”

“…It was found that the use of external carbon sources [20][21][22][23] in the reactor was a viable method of enhancing sequencing batch reactor (SBR) performance. In this study, the relationship between incomplete denitrification caused by a low C/N ratio and sludge foaming was investigated.…”