Iranian Journal of Chemical Engineering (IJChE)

Abstract This study evaluates the effectiveness of the aluminum sulfate coagulation in treating the wastewater from thermal power plants to efficiently remove pollutants. Key operational parameters—the pH of the wastewater (5 to 9), dosage of coagulant (10 to 40 mg/L), and mixing time (10 to 30 minutes)—were systematically investigated for their impact on the removal of chemical oxygen demand (COD) and total dissolved solids (TDS). The coagulation mechanism involves the hydrolysis of aluminum sulfate, generating charged species that neutralize particle charges, followed by adsorption, bridging, and floc formation, which together promote the aggregation and sedimentation of pollutants. Utilizing the response surface methodology (RSM) with the Design Expert software, the process was optimized, revealing that a pH near 7.4, dosage of approximately 40 mg/L of the coagulant, and mixing time of around 22 minutes maximize the treatment efficiency. Under these conditions, the removal of COD and TDS reached 71.1% and 97.3% respectively, demonstrating the potential of this approach for the sustainable and cost-effective wastewater treatment in thermal power plant operations.

Abstract Dialysis is a membrane based separation process in which the concentration gradient across the membrane is the driving force resulting in a flow of material from one side of the membrane to the other. In this study membranes (Accurel, Celgard, GVHP, PM30 and PTHK) with different pore sizes were employed to characterise the transport of lithium ion in various (0.01, 0.1, 0.5, 1 and 2.5 w/v percent) initial feed concentrations via the dialysis process. This may be considered as a basis for wastewater treatment containing metal ions. The results show that low initial feed concentration causes less passage of ions through the membrane due to low driving force i.e. concentration gradient across the membrane. The investigation of the effect of membrane pore size on ion transport revealed that large pore size membranes provide less penetration of the metal ions through the membrane. These reproducible results, which are not expected, have been explained by the transport mechanism. Two types of mechanisms (extensive versus intensive) have been suggested for metal ion transport through different membranes. If the mechanism of ion transport is intensive, more ions pass through the membrane. Extensive mechanism results in lower ion transport through the membrane.

Abstract Surfactants are one of the major components (10- 18%) of detergents and household cleaning products and are used in high volumes in developed countries. In the present research work, the ability of rice husk as a low cost adsorbent for anionic and nonionic surfactants in wastewater has been studied.
The maximum removal efficiency for anionic surfactants was 97%, in an aqueous solution that contains 10mg/lit sodium linear alkyl benzene sulphonate in pH 2 and for nonionic surfactants was up to 75% in an aqueous solution that contains 20mg/lit nonyl phenol ethoxylate in pH 6-7.
The mechanism of surfactant removal by rice husk was attributed to the physicochemical characteristics of rice husk. In addition, the size of micelles and critical micelle concentration are two important factors in the removal yield.
 
 
 
 

Abstract Recently, use of naturally-occurring low-cost and harmless material for removal of trace contaminants from colored wastewater has attracted extensive attention. In this study, silkworm pupa has been used as a basic dye adsorbent. Adsorption capacity and isotherms have been assessed. Results show that adsorption isotherms can be expressed well by Langmuir equation. The effects of parameters such as pH, temperature, agitation time and speed on the adsorption efficiency were investigated. It was found that among those factors the pH is the most pronounced one. Also the adsorption capacity of pupa towards the various cationic dyes is changed as follows: basic blue >basic yellow >basic red.