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In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene.

A halo-tolerant bacterial consortium comprised of Pseudomonas pseudoalcaligenes strain R1, Bacillus subtilis subsp. inaquosorum R2 and Shewanella chilikensis strain AM1 were isolated and used as inoculums in a moving bed bioreactor for treatment of a saline petrochemical wastewater. Observations demonstrated the halo-tolerant capability of isolated strains up to around 3.2%. The influence of varying organic loading rates and TDS concentrations were evaluated on bioreactor efficiency and biokinetic coefficients. A COD removal of 77% was observed for organic loading rate of less than 2.7 kg COD m-3 d-1 and TDS concentrations of 25,000 and 30,000 mg L-1. Growth yield (Y) varied from 0.178 to 0.129 mg VSS mg COD-1 in different TDS concentrations. Results indicated that the biokinetic coefficients were in the range close to typical ranges reported for similar industrial wastewaters, except that of the half saturation constant (Ks). [ABSTRACT FROM AUTHOR]

Treatment of a saline petrochemical wastewater with BOD 5 /COD ratio of less than 0.1 was investigated using a consortium consisted of three isolated salt-tolerant bacteria namely, Kocuria turfanesis , Halomonas alkaliphila and Pseudomonas balearica . Selected bacteria were isolated from petrochemical wastewater containing mineral salt mediums of 3% salinity. A lab-scale activated sludge bioreactor was used for startup in batch mode operation and after obtaining the MLSS concentration of about 3000 mg/L, the operation was changed to continuous flow mode to determine the biokinetic coefficients under different organic loading rates of 0.33–1.21 kg CODm −3 d −1 . The COD removal efficiency of 78.7%–61.5% was observed for treatment of real saline wastewater with a decreasing trend along with increasing the organic loading rate. In addition, results of kinetic investigation demonstrated that the yield(Y), endogenous decay coefficient (k d ), maximum reaction rate (K max ), maximum specific growth rate ( μ max ) and saturation constant ( K s ) were 0.54 mg VSS mg COD −1 , 0.014 day −1 , 1.23 day −1 , 0.66 day −1 , and 1315 mg L −1 , respectively. [ABSTRACT FROM AUTHOR]

A lab-scale cross flow membrane bioreactor (CF-MBR) was operated to determine the biokinetic coefficients under MLSS concentrations of 5000 and 3000 mg/L. The investigation showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μm) and the saturation constant (KS) were 0.276 mg/mg, 0.07 /day, 0.653 /day, and 396.62 mg COD/L respectively for MLSS 5000 mg/L, and 0.222 mg/mg, 0.09 /day, 1.2 /day, and 659.45 mg COD/L for MLSS 3000 mg/L. The values of kinetic coefficients were within the normal range of the activated sludge process found in the literature, except the values of Y. However, value of Y increased with the increase of MLSS. Kinetic parameters determined from CF-MBR process were used to simulate the effluent COD. The simulation study showed good agreement between model prediction and experimental data. Sensitivity analysis was carried out to determine influence of biokinetic parameters on the effluent substrate concentration. From the analysis, it was evident that kd and KS were directly proportional to the effluent substrate concentration, while μm was inversely proportional. [ABSTRACT FROM AUTHOR]

Biokinetic coefficients and efficiency for three activated sludge processes including conventional, extended aeration, and contact stabilization were determined in pilot-scale for six months in Isfahan south municipal wastewater treatment plant. These systems were operated under two different MLSS concentrations in aeration tank. For each MLSS, five periods were considered in base of flow rate and sludge retention time (SRT). The samples from the influent wastewater, reactor and effluent were collected periodically and experimented by the Standard Methods. The data were analyzed by the Excel and SPSS softwares. The investigation showed that the yield coefficient (Y), decay coefficient (kd), maximum specific growth rate and saturation constant (Ks) for conventional activated sludge process were in the range of 0.48-0.8 mgVSS/mg sCOD, 0.0189-0.026 1/day, 0.95-0.98 1/day and 52-71 mg sCOD/L, extended aeration: 0.6174-1.2512 mgVSS/mg sCOD0.0198-0.0309˓ 1/day 1.96-3.17 ˓ 1/day and 311.7-508 mg sCOD/L and for contact stabilization: 0.6322-0.713 mgVSS/mg sCOD1 0.0172-0.0387 ˓/d0.23-1 0.42/d and 13.8-50.8 mg sCOD/L, respectively. In the conventional and contact stabilization processes values of the coefficients were within the range of those reported in the literature. However, in the extended aeration process, values of Ks and Y in MLSS of 5000mg/L were out of ranges. The sensitivity analysis of changes in the biokinetic coefficients showed direct relationship of kd and Ks with the concentration of the effluent substrate. Whereas µmax is inversely related to concentration of the effluent substrate. In addition, regardless of the type of substrate and MLSS concentration, the effluent substrate concentration is more sensitive to µmax than kd and Ks. The results also showed a COD removal efficiency ranging for conventional process between 83 and 92.5%, for extended aeration process between 88 and 93.8%, and for contact stabilization process 77 and 92%. The effluent COD was simulated using the biokinetic coefficients determined during the study. [ABSTRACT FROM AUTHOR]

• Quantity and quantify of foaming were evaluated at different SRTs and OLRs. • Protein content of EPS can lead to more foam formation than carbohydrate. • Foaming phenomenon can be controlled by optimizing OLR values. • More OLR is not providing higher values of maximum specific growth rate (μm). This work aims to control foaming in a submerged membrane bioreactor (SMBR) by optimizing the organic loading rate (OLR) and sludge retention time (SRT) values to decrease the extracellular polymeric substance (EPS) production used for the pharmaceutical wastewater treatment. Four lab-scale SMBRs were operated for a period of more than 8 months to determine the biokinetic coefficients and optimize the SMBR systems operation under the SRT of 5, 10, 15, 20, 25 days and OLRs of 0.03-0.32 gCOD/L.day. The investigation revealed that the lowest foaming quantity was at an organic loading rate of 0.32 gCOD/L.day and a sludge retention time of 15 days related to few protein concentration of EPS. The results also showed that the foaming quality at the OLR of 0.03 gCOD/L.day was higher compared to the greater OLRs in all SRTs. It was found that the yield (Y), the endogenous decay coefficient (k d), the maximum specific growth rate (μ max), and the saturation constant (K s) of four SMBRs were in the range of 0.073-0.310 mg/mg, 0.985-3.119 day−1, 1.249-3.672 day−1, and 2.63-106.671–232.55 mg/mg, 1–3.156 day mgCOD/L, respectively. Furthermore, the most appropriate operating condition to activated sludge among the SMBRs was the OLR of 0.1 gCOD/L.day and SRT of 15 days. Under these optimum conditions, a 92.8 % COD removal efficiency and 3.708 1/day μ max were achieved. [ABSTRACT FROM AUTHOR]

The halotolerant bacteria including Pseudomonas stutzeri strain Ahv‐S12, Bacillus vietnamensis strain Ahv‐Q1 and Brevibacterium sediminis strain Ahv‐Z20 were used as inoculums in an integrated powder activated carbon/activated sludge bioreactor. The influence of organic loading rates (OLRs) and total dissolved solids (TDS) concentrations on chemical oxygen demand (COD) removal efficiency was evaluated. Furthermore, biokinetic coefficient was evaluated under TDS variation. Results showed that the COD removal value of 68.32% was observed in OLR of 0.4 kg COD m−3 day−1 and TDS concentrations of 20,000 mg L−1. Higher OLR and TDS concentration led to lower COD removal efficiency. On the other hand, the biodegradation function of isolated salt tolerant strains was much more affected by salinity rather than OLR. Results of biokinetic coefficient determination showed that yield value (Y), kd, K, and μmax were 0.199–0.274 mgVSS mg COD−1, 0.016–0.038 day−1, 0.48–0.922 day−1 and 0.097–0.244 day−1, respectively. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13088, 2019 [ABSTRACT FROM AUTHOR]