More than 12000 Ganesh and Gauri idols were immersed on 4th day of Ganpati Visarjan at various visarjan sites in Pune yesterday. At the various ghats, families performed the final rituals before immersing the idol. Visarjan process was going on even after midnight. Environment conscious devotees were seen opting for tank immersions. <br/>'<br/>Pune Municipal Corporation deployed staff along the rivers' ghats to help immerse the idols in tanks placed by the banks. The civic body had set up the tanks in an effort to avoid pollution of water bodies but a few people went ahead and immersed the idol in the river.<br/>'<br/>Huge containers were also placed along the ghats to collect the nirmalya, which would later be composted into manure.