A Novel Method for Determining Microbial Kinetics

Understanding microbial growth is essential to any research conducted in the fields of microbiology and biotechnology. Current methods of determining growth characteristics of microbes involve subjective graphical interpretations of linearized logarithmic data. Reducing error in logistical data decreases disparity between graphical and analytical predictions of microbial characteristics. In this study, a method has been developed to calculate the kinetics of microbial characteristics utilizing a modified Maclaurin series. Convergence of this series approaches the true kinetic value of microbial characteristics to include specific growth rates. In this research, a modified Maclaurin series is used to evaluate microbial kinetics in comparison to graphical determinations.

Effect of endogenous hydrogen utilization on improved methane production in an integrated microbial electrolysis cell and anaerobic digestion： Employing catalyzed stainless steel mesh cathode

Improving the production of methane, while maintaining a significant level of process stability, is the main challenge in the anaerobic digestion process. Recently, microbial electrolysis cell(MEC) has become a promising method for CO_2 reduction produced during anaerobic digestion(AD) and leads to minimize the cost of biogas upgrading technology. In this study, the MEC-AD coupled reactor was used to generate and utilize the endogenous hydrogen by employing biocompatible electrodeposited cobalt-phosphate as catalysts to improve the performance of stainless steel mesh and carbon cloth electrodes. In addition, the modified version of ADM1 model(ADM1 da) was used to simulate the process. The result indicated that the MEC-AD coupled reactor can improve the CH_4 yield and production rate significantly. The CH_4 yield was enhanced with an average of 48% higher than the control. The CH_4 production rate was also increased 1.65 times due to the utilization of endogenous hydrogen.The specific yield, flow rate, content of CH_4, and p H value were the variables that the model was best at predicting(with indexes of agreement: 0.960/0.941, 0.682/0.696, 0.881/0.865, and 0.764/0.743) of the process with SSmeshes 80/SS-meshes 200, respectively. Employing the catalyzed SS mesh cathode, in the MEC-AD coupled reactor, could be an effective approach to generate and facilitate the utilization of endogenous hydrogen in anaerobic digestion of CH_4 production technology, which is a promising and feasible method to scale up to the industrial level.

Determination and discussion hydraulic retention time in membrane bioreactor system

Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K , saturation constant K s, maintenance coefficient m , maximum specific growth rate μ m and observed yield coefficient Y obs . Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ=1.1(1/β-1)(K s +S)/KX 0, for petrochemical wastewater treatment K and K s equaled 0 185 and 154.2, respectively.

Microbial insecticide model and homoclinic bifurcation of impulsive control system

A new microbial insecticide mathematical model with density dependent for pest is proposed in this paper.First,the system without impulsive state feedback control is considered.The existence and stability of equilibria are investigated and the properties of equilibria under different conditions are verified by using numerical simulation.Since the system without pulse has two positive equilibria under some additional assumptions,the system is not globally asymptotically stable.Based on the stability analysis of equilibria,limit cycle,outer boundary line and Sotomayor's theorem,the existence of saddle-node bifurcation and global dynamics of the system are obtained.Second,we consider homoclinic bifurcation of the system with impulsive state feedback control.The existence of order-1 homoclinic orbit of the system is studied.When the impulsive function is slightly disturbed,the homoclinic orbit breaks and bifurcates order-1 periodic solution.The existence and stability of order-1 periodic solution are obtained by means of theory of semi-continuous dynamic system.