USING pH AS A REAL-TIME CONTROL PARAMETER FOR WASTEWATER TREATMENT AND SLUDGE DIGESTION PROCESSES

Abstract

The alternating aerobic-anoxic (AAA) process offers many advantages for wastewater treatment and sludge digestion. Laboratory scale experiments were conducted to investigate the feasibility of using pH as a realtime control parameter for this process. Several well defined control points on the pH curve were identified, e.g., ammonia valley and nitrate apex. These points were directly related to the alternating nitrification and denitrification reactions in the process, and were found to be consistent with those previously identified using ORP. Although both pH and ORP can be used as real-time control parameters, pH provides several additional advantages over ORP. Based on these findings, real-time control strategies (fixed pH setpoints and dynamic pH control) were developed and tested. Results from laboratory scale AAA sludge digestion using fixed pH setpoints (6-8) indicated that 36% MLVSS reduction, 39% TN reduction and almost 48% saving in aeration energy was achieved after 300 hrs of digestion.

Process Control of an Alternating Aerobic‐Anoxic Sequencing Batch Reactor for Nitrogen Removal via Nitrite

“…The pH approached a low level of 6.0-6.1 without an ammonia valley, as suggested in the literature [20] and DO tended to be constant at a high level. Therefore, the pH and DO-time characteristics indicated that nitrification was inhibited due to the lack of alkalinity, (arrow B in Fig.…”

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

“…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-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)(8)(9). According to these control points, the flexible hydraulic retention time (HRT) from cycle to cycle was obtained and a high and stable removal rate of nitrogen and energy saving were achieved using a real-time control strategy.…”

Effectiveness of Oxidation-Reduction Potential and pH as Monitoring and Control Parameters for Nitrogen Removal in Swine Wastewater Treatment by Sequencing Batch Reactors

“…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)(6)(7)(8)(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.…”