Mr Guah holds both the Master of Engineering and Bachelor of Engineering (Hons) Degrees in Civil Engineering from the Nanyang Technological University, Singapore.

In 2018, Mr Guah and Samwoh formed a joint venture, SG Enviro Pte. Ltd., focusing on emerging sustainable environmental technologies suitable for application in the regional countries. He was invited to join the Board as a Director of Samwoh Holdings Pte. Ltd. in 2020.

Mr Guah has more than 20 years of experience with various organisations in engineering, sales, business development and directorship, including his first stint with Samwoh from 2003 to 2009 as the Head of Business Development.

Being a passionate green activist, Mr Guah is deeply associated with the solid waste management profession in Singapore and the region. He has been serving the Waste Management and Recycling Association of Singapore (WMRAS) since 2006 and assuming the role of Chairman from 2009 to 2012. He was subsequently inducted as a lifetime Honorary Member upon his retirement as Chairman. He was also elected to the Board of International Solid Waste Association (ISWA) from 2010 to 2012.