Phenol contaminated petroleum refinery wastewater presents a great threat on water resources safety. This study investigates the effect of microwave irradiation on removal of different concentrations of phenol in an attempt for petroleum refinery wastewater treatment. The obtained results show that the MW output power and irradiation time have a significant positive effect on the removal efficiency of phenol. The kinetic reaction is significantly affected by initial MW output power and initial phenol concentrations. Response surface methodology (RSM) was employed to optimize and study the interaction effects of process parameters: MW output power, irradiation time, salinity, pH, and H₂O₂ concentration using central composite design (CCD). From the CCD design matrix, a quadratic model was considered as an ultimate model (R² = 0.75) and its adequacy was justified through analysis of variance (ANOVA). The overall reaction rates were significantly enhanced in the combined MW/H₂O₂ system as proved by RSM. The optimum values for the design parameters of the MW/H₂O₂ process were evaluated giving predicted phenol removal percentage of 72.90% through RSM by differential approximation and were confirmed by experimental phenol removal of 75.70% in a batch experiment at optimum conditions of 439 W MW power, irradiation time of 24.22 min, salinity of 574 mg/L, pH 5.10, and initial H₂O₂ concentration of 10% (v/v).

The research presents an overview on sludge types, characteristics, and methods of treatment. Additionally, using the sludge as an energy source for future plans was studied as well. The paper focused mainly on analyzing different sludge characteristics based on the previous studies. Wastewater sludge produced from the primary, secondary, and tertiary treatment processes was analyzed. It was mainly composed of many organic and inorganic materials. Some of the materials were removed by physical and other required chemical or biological processes. Most of the sludge was solid, semi-solid, and muddy with the harmful substances such as proteins, phenols, and hazardous materials. The study explained different methods of energy production as well. At the end, it was concluded that every type of sludge could provide energy and be a basic financial product for the selected area, and keep environment safely and healthy as well. The calculated quantity of dry sludge for 1,000,000 inhabitants in Erbil City, Kurdistan Region-Iraq, was 50,000 kg/d, which produced calorific value of 9.5 · 107 K. cal./day. Furthermore, the essential area for under drain sand bed area was 5,100 m2.

Currently, the primary source of pollution is crude oil production. Crude oil production has dramatic consequences for farmlands, communities, and in terms of the construction materials required for earthworks. The main aims of the present study were to reduce the level of pollution caused by oil production in the Khurmala soil and then reuse it as a construction material. Soil remediation using the solidification/stabilization method was applied in the field using Portland limestone cement (CEM II). The performance of using CEM II in the remediation process was then investigated in the laboratory by taking the natural, contaminated, and treated soils from the Khurmala site. Furthermore, the results of the soils were compared with their corresponding soil samples using ordinary Portland cement (OPC). The comparison was performed by investigating the physical, chemical, and mechanical properties of the soils. The discussion was supported using the scanning electron microscopy (SEM) results. Chemical and SEM results revealed that there were fourfold and tenfold decreases in the percentage of oil and grease using OPC and CEM II, respectively, confirming the higher performance of using CEM II over OPC. The values of the coefficient of permeability, shear strength parameters, and California bearing ratio of the treated soils were significantly improved, compared to those of the contaminated soils.

Concrete is one of the most reliable, durable, and desired construction materials. It became the second most used material after water in the world. Many studies and investigations reported that the amount of CO2 released into the atmosphere is nearly 1 ton in the production of 1 ton of cement, which contributes to 5-7 % of total CO2 emissions worldwide. Geopolymer concrete (GPC) is a new development in the world of concrete, which does not need to use cement. The most used materials in geopolymer are by-products such as fly ash, ground granulated blast furnace slag, silica fume, etc. Industrial waste materials are a great problem for human health, environment, and scarcity of land, therefore, reusing them in GPC manufacturing can be seen as a great advantage. Fortunately, most of the recent research concludes that most by-products exhibit similar or better durability, mechanical and physical properties when compared to ordinary concrete. Therefore, GPC became a good sustainable engineering material with many advantages over conventional concrete, such as high early strength, excellent resistance to chemical attacks and steel reinforcement corrosion, elimination of water curing, low cost, etc. This paper reviews the process of geopolymer concrete, constituents, types, properties, durability, and particular applications.