Pars Energy & Environmental (PEN) Group registered under the trade name of 'Zist Energy Pars" in Iran, is an independent, non-governmental, private section, and limited liability company with special corporation engaged in variety of projects in Iran. PEN has been established in order to provide services in the field of civil engineering and environmental studies, management and planning. Protecting, maintaining and improving the environmental status of development projects, services and infrastructure with a sustainable development perspective are one of the major goals of department of environmental studies. Civil department also focuses on designing water and wastewater treatment plans, landfills and urban projects. The points of view of PEN senior management are active and dynamic ever since, and it has always attempted to introduce the best available techniques (BATs) to develop the best environmental performance (BEP) in development projects.