Experiment of treating polluted wastewater resulting from petroleum refineries using pyramid solar still distillation system to eliminate hydrocarbon toxicity

The current research contributes to addressing the exploitation of the abundance of solar energy in providing potable water treatment and reviewed a green and inexpensive mechanism for treating wastewater from the petroleum oil refinery industries that is contaminated with organic polluting hydrocarbon compounds that are harmful to the environment. The experiment was conducted in the city of Samawah in Iraq during the month of January for the treatment of petroleum wastewater by using a local pyramidal solar distillation system aided with a filtration basin made of recycled materials at varying weights of charcoal (100–2,000 g), time (1–18 h), pH (6–7), and temperature (28°C–88°C). The results showed a high performance of the passive solar system in treating wastewater from pollutants corresponding to 99.5% biological oxygen demand removal efficiency at optimum conditions of pH (6), 2,000 g of charcoal, 18 h contact time, and internal and external temperatures of 28°C and 48°C, respectively. The statistical test confirmed that the pH and weight of charcoal have a significant effect on the overall performance of the pyramidal solar distillation system at a 95% confidence interval (p-value < 0.05). The key characteristics of the finished waterfalls are within the minimum permissible limits for safe and clear water discharge.