Study on the Balance of Oxygen in Supply and Demand in Wastewater Treatment Plant

In order to accurately evaluate the comprehensive operation efficiency of aerobic biological treatment system in wastewater treatment plants (WWTPs), the process state aeration performance tester and the specific oxygen uptake rate online monitoring device were used to measure the oxygenation performance and the activated sludge performance in aeration tank, and the comprehensive operation efficiency of aerobic tank was evaluated by combining physical-chemical indexes and water quality analysis of the treatment system. The results showed that the oxygen transfer efficiency (OTE) of aerators under process state are reduced by 13.07% and 14.48% respectively compared with that in clean water in the No.3-tank and No.6-tank, and the aeration uniformity index (IAU) is 4.86 and 1.46 respectively. The oxygen uptake rate (OUR) in the third corridor decreased significantly, but dissolved oxygen (DO) was a high level. Oxygen in supply (Qs) was much greater than oxygen in demand (Cs), which have resulted a large waste of energy consumption. Finally, the subsection regulation strategy was proposed based on the principle of oxygen balance. The results of this study will not only help the WWTP to achieve energy-saving and consumption-reducing, but also stable operation.

Assessment of toxicity and kinetic effects of erythromycin on activated sludge consortium by fast respirometry method

Background: The present study aimed to assess the acute impact of erythromycin (ERY) as an inhibitor on peptone mixture utilization of activated sludge (AS) consortium. Methods: For this purpose, the inhibition of oxygen consumption was used based on the ISO 8192:2007 procedure. In this method, the AS consortium (10-day age) was extracted from lab-scale membrane bioreactor, then, percentage inhibition for total, heterotrophic, and nitrifying microorganisms, in separate batch respirometric tests were calculated in the absence and presence of N-allylthiourea (ATU) as a specific Nitrification inhibitor. Results: The obtained data showed that the height of oxygen uptake rate (OUR) profiles and amount of oxygen consumption reduced with increasing ERY dose. The half-maximal effective concentration (EC50) of ERY for heterotrophic and nitrifier microorganisms were 269.4 and 1243.1 mg/L, respectively. In Run 1, the kinetic coefficients bH, fA,H, YH, and µH were calculated as 2.61 d-1, 0.44, 0.4945 mg VSS/mg COD, and 0.047 d-1, respectively. Also, for maximum ERY concentration (1000 mg/L), the kinetic coefficients bH., fA,H, YH, and µH were calculated as 2.27 d-1, 0.3, 0.4983 mg VSS/mg COD, and 0.0049 d-1, respectively. Conclusion: The findings showed that the inhibitory impact of ERY was observed as a decrease in the amount of oxygen consumption by OUR profiles in rapid respirometric method (ISO 8192), which offered a novel insight for the acute inhibitory impact of this antibiotic. Also, chemical oxygen demand (COD) as an overall substrate parameter is most helpful in interpreting the behavior and the metabolic functions of AS systems.

Model Parameters for Aerobic Biological Sulfide Oxidation in Sewer Wastewater

Sulfide related odor and corrosion are two of the major problems associated with the operation and maintenance of sewer networks. The extent of the problems is governed by several complex and interrelated processes. Sulfide oxidation is typically the most important process for sulfide removal in wastewater from aerobic gravity sewers. Despite the significance of the process, little is known about the significance of the growth of sulfide oxidizing bacteria (SOB) during the transport of wastewater. Biological sulfide oxidation in wastewater from sewers was investigated in a series of oxygen uptake rate (OUR) experiments. The experiments showed that, for oxygen nonlimiting conditions, sulfate was produced, with elemental sulfur as an intermediate. During each experiment, the activity of the sulfide oxidizing bacteria increased significantly. This was interpreted as the result of bacterial growth related to the oxidation of intermediately stored elemental sulfur. A model concept describing biological sulfide oxidation, with intermediary storage of elemental sulfur and associated growth, was developed. The model was calibrated against the experimental results. The observed average growth rate and yield constant for the SOB were determined at 1.98 d−1 and 0.17 g Chemical Oxygen Demand (COD) per g sulfur, respectively. These values correspond to reported values for mixed cultures of autotrophic SOB.

Mathematical Analysis of Oxygen Uptake Rate in Continuous Process under Caputo Derivative

In this paper, the wastewater treatment model is investigated by means of one of the most robust fractional derivatives, namely, the Caputo fractional derivative. The growth rate is assumed to obey the Contois model, which is often used to model the growth of biomass in wastewaters. The characteristics of the model under consideration are derived and evaluated, such as equilibrium, stability analysis, and steady-state solutions. Further, important characteristics of the fractional wastewater model allow us to understand the dynamics of the model in detail. To this end, we discuss several important analyses of the fractional variant of the model under consideration. To observe the efficiency of the non-local fractional differential operator of Caputo over its counter-classical version, we perform numerical simulations.

A Single-Phase Modelling for the Oxygen Uptake Rate in Excess Post-Exercise Oxygen Consumption

A two-parameters [a rate constant k and a factor f (0≤f < 1)] modelling, describing satisfactorily the post-exercise oxygen uptake rate (VO2) as a function of the recovery time (t), is presented. f controls the rate equation dVO2/dt, particularly at t = 0 where (dVO2/dt)t=0 ∝ −k(1−f), a less abrupt decay than (dVO2/dt)t=0 ∝ −k expected from an exponential. Fitting the model to a set of experimental VO2 vs t data after a 3MT it was found a set of values with f close to 0 and another with f > 1/2, with a narrow distribution of values for the half-recovery time τ1/2=(1/k)ln[(2−f)/(1−f)] (〈τ1/2〉=0.641 min, σ = 0.062 min), very similar to that (T) found by fitting a model based on a logit transform (〈T〉 = 0.672 min, σ = 0.081 min). The parameter f is a reliable index of the initial acceleration of the oxygen uptake rate recovery (and likely of the heart rate recovery) and, together with the half-recovery time τ1/2, may be a useful method in characterizing and monitoring performs and exercise forms, very important in the physiology area.