4-chlorophenol removal by air lift packed bed bioreactor and its modeling by kinetics and numerical model (artificial neural network).

4-chlorophenol (4-CP) is a hazardous contaminant that is hardly removed by some technologies. This study investigated the biodegradation, and physical 4-CP removal by a mixed microbial consortium in the Airlift packed bed bioreactor (ALPBB) and modeling by an artificial neural network (ANN) for first the time. The removal efficiency of ALPBB was investigated at 4-CP(1-1000 mg/L) and hydraulic retention time (HRT)(6-96 hr) by HPLC. The results showed that removal efficiency decreased from 85 at 1 to 0.03% at 1000 mg/L, with increasing 4-CP concentration and HRT decreasing. BOD5/COD increased with increasing exposure time and concentration decreasing, from 0.05 at 1000 to 0.96 at 1 mg/L. With time increasing, the correlation between COD and 4-CP removal increased (R2 = 0.5, HRT = 96 h). There was a positive correlation between the removal of 4-CP and SCOD by curve fitting was R2 = 0.93 and 0.96, respectively. Moreover, the kinetics of 4-CP removal follows the first-order and pseudo-first-order equation at 1 mg/L and other concentrations, respectively. 4-CP removal modeling has shown that the 2:3:1 and 2:4:1 were the best structures (MSE: physical = 0.126 and biological = 0.9)(R2allphysical = 0.999 and R2testphysical = 0.999) and (R2allbiological = 0.71, and R2testbiological = 0.997) for 4-CP removal. Also, the output obtained by the ANN prediction of 4-CP was correlated to the actual data (R2physical = 0.9997 and R2biological = 0.59). Based on the results, ALPBB with up-flow submerged aeration is a suitable option for the lower concentration of 4-CP, but it had less efficiency at high concentrations. So, physical removal of 4-CP was predominant in biological treatment. Therefore, the modification of this reactor for 4-CP removal is suggested at high concentrations.

Effect of land use on cultivable bioaerosols in the indoor air of hospital in southeast Iran and its determination of the affected radius around of hospital.

This study aimed to evaluate the effect of land use on hospital bioaerosols and determine the effective radius. The concentration of fungi and bacteria in indoor and outdoor air was determined by the 0800NIOSH. Then land uses were determined by Google earth within a range of 0.5-5 km around three hospitals. Data were analyzed by using Spearman correlation, and a t test was used to determine differences between groups. Data were recorded in Excel and entered into Matlab2018 for analysis. The results of the study showed that the concentration of fungi and bacteria was higher in the indoor and outdoor hospital B (bacteria = 343-43, fungi = 106-291 CFU/m3) (P = 0.04). Maximum land use was also found in hospitals A and B related to urban and bare, while in hospital C, they were urban and bare. Mathematical modeling has shown that the trend of land-use variation over different radii consisted of the Gaussian model (in hospital B) and Fourier series (in hospitals A and C). Besides, there was a positive correlation between the bare and fungal and bacterial concentrations. Finally, the most effective bare radius of application on the indoor and outdoor fungi was 4 and 5 km, respectively (R2 = 0.99). The effective radius for reducing fungi and bacteria by creating green space was 0.5 and 3 km from the hospital center (R2fungi = - 0.99, R2bacteria = - 0.8). Based on these results, land use is an effective factor in airborne fungi and bacteria in hospitals. Therefore, their control and management of land use during 5 km is necessary to reduce pollution.

Effects of Er,Cr:YSGG Laser Treatment on Human Gingival Fibroblast Attachment, Viability and Morphology of Root Surface: An In Vitro Study.

Rehabilitation of periodontal support is the main goal of therapies for periodontitis. Hand instrumentation with curettes, piezoelectric ultrasonic scalers and lasers, such as Er,Cr:YSGG, are used for this purpose. This study was designed to evaluate human gingival fibroblast viability attachment to root surfac after modification with the mentioned therapeutic alternatives. Lasers showed significantly lower cell viability after 72 hours compared to hand instrumentation and ultrasound, probably due to more irregular root surfaces after treatment.