The new projects are apart from a £9m investment the company has made in recent years.
As part of the work, the company will replace its existing heavy fuel oil units with new gas boilers that will reduce carbon emissions at the site by 3,500 tonnes per year.
The company formed a partnership with Natural Resources Wales for the new effluent treatment plant. The investment plans also include enhancing capacity at the site to meet growing demand for the company's cheeses.
Meanwhile, the company is hiring for more milk in West Wales as part of this investment drive.
First Milk said that further investments at the creamery are currently being scoped out for 2014 and 2015.
