Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Current Issue

The use of bioreactors at sewage treatment plants solves an environmental problem at water utilities in the Udmurt Republic, as sludge beds are overflowing due to the fact that tens of tons of sewage sludge have been stored on sludge beds every day since the 1980s and amount to hectares of land.

The results of experimental studies on the processing of wastewater sludge in the Biotechnology laboratory were analyzed to improve the efficiency of the technological process for the disposal of organic waste using a biogas plant and a process activator.

The methodology for preparing a biogas plant for entering the operating mode and further operation is presented. An algorithm for experimental studies using a biogas plant and obtaining biogas from organic waste is presented.

The article presents an analysis of the results of experimental studies of sewage sludge treatment under periodic psychrophilic and, subsequently mesophilic operating conditions of the bioreactor in relation to the climatic conditions of the Udmurt Republic. The results of experimental studies in the article are presented in the form of graphical dependencies of the volume of produced biogas on the temperature and duration of the process.

The article presents the dynamics of changes in the volume of produced biogas depending on the increase in temperature and duration of the process under the mesophilic operating mode of the bioreactor. On the first day of the experiment under the mesophilic mode in the bioreactor, the volume of produced biogas was 2.15% (7.41 g) at a temperature of 32°C; with increasing temperature, the volume of produced biogas increased. The maximum biogas production was observed on the fifth day of the experiment under the mesophilic mode and amounted to 7.66%, which corresponds to 26.41 g.

The recommended loading volume of biomass into the bioreactor is 80 liters. In accordance with the actual conditions of the sewage treatment facilities, the volume of biogas produced will be 26.000 m³ of methane daily during the period of anaerobic fermentation in the bioreactor. To solve the environmental problem, it is necessary to install a complex of bioreactors at the water utilities of the Udmurt Republic.

Recently, abundant agricultural solid waste has been utilized as sustainable biosorbents for removing heavy metals from aqueous solutions. However, the influence of the carbonization parameters on the specified biosorbent performance has not been well discussed. In this study, we developed the removal efficiency (RE) of Exhausted Kahwa Coffee (EKC) as a low-cost and high-efficiency biosorbent for Cd (II) under various carbonization temperatures (300 – 600°C) and time (1- 4 h).

The batch biosorption test showed that the EKC biochar with a carbonization temperature of 500˚C and time of 4 h removed 97% of Cd (II) from the solution. The biosorption performance was further investigated by integrating the physicochemical changes in the surface and functional groups of the EKC biochar at different temperatures using BET, SEM, and FT-IR instruments.

The FT-IR showed alterations in the functional groups, while the BET data and SEM images demonstrated that the porous surface of the biochar developed as the temperature increased. Furthermore, the biosorption test data was plotted in the Langmuir and Freundlich isotherm models, where the Langmuir isotherm model showed the better fit of EKC biochar. The maximum biosorption capacity of the EKC biochar on Cd (II) was calculated at 3.41 mg/g by fitting the equilibrium data to Langmuir isotherm equations.

It was found that the kinetic data fitted well with Pseudo-Second-Order (PSO) with a correlation coefficient of R² = 0.99. These findings imply the influence of the carbonization parameter on the potential biosorption of the EKC biochar on Cd (II).

Centrifugal pumps are key equipment used for fluid transfer in the chemical industry. During the start-up process of high-speed centrifugal pumps, the hydraulic characteristics such as flow rate and head will change significantly, and the optimization of the pump start-up process can improve its stability and service life, which will make centrifugal pumps more efficient in chemical production.

Achieving a fast and stable startup process has always been a goal in the engineering application of high-speed centrifugal pumps.

First, the mathematical relationship between the torque and speed of the centrifugal pump is established. Then, based on the physical characteristics of the DC motor and considering the centrifugal pump torque as the load, a mathematical model of the high-speed DC centrifugal pump is developed. A fuzzy PI controller for the high-speed DC centrifugal pump is designed by integrating traditional PI control methods with fuzzy control theory to manage the startup process. Optimization algorithms are employed to optimize the parameters of the fuzzy PI controller.

Before optimization, the settling time was 0.33 s, the motor speed overshoot was 7.69%, the head overshoot was 3.77%, and the flow rate overshoot was 7.69%. After optimization, the settling time improved to 0.25 s, the motor speed overshoot was reduced to 6.3%, the head overshoot to 3.1%, and the flow rate overshoot to 6.3%.

A comparison of simulation results before and after parameter optimization demonstrates that the optimized fuzzy PI control yields better dynamic performance during the startup process of the high-speed DC centrifugal pump.