Who we are

Yellow Tree is passionate about the environment and about serving others. We are a team of engineers and environmental scientists that specialise in stack emissions testing, and we love our work.

Who we are

Our awesome staff are here to serve.

Jess Ritten

Jess Ritten

Financial Manager

BSc Genetics, Hon Finance

Jess is a gem! Her intellect, incredible work ethic and care for people make her an asset. She oversees Yellow Tree’s finances and HR, but also has extensive knowledge of the Air Quality Legislation and supports the consulting team.

Matthew Mwepu

Matthew Mwepu

Lead Scientist

NDip Mech Eng

Matt is our most experienced stack tester. With a wealth of knowledge spanning the testing of all emissions from particulate matter through to dioxins and furans, Matt is our guy! We love his confidence and bold leadership!

Rumbi Zireva

Rumbi Zireva

Air Quality Consultant

BSc Chem Eng, MSc Med

Rumbi is both incredibly bright and dedicated. As a talented chemical engineer (with a Masters degree) she heads up our consulting department doing AEL applications, carbon tax consulting, and NAEIS submissions, and pursuing our ISO 17025.

Alen Siwela

Alen Siwela

Assistant Scientist

NDip Chem Eng

Alen’s life is characterised by perseverance and his story is inspirational. Having lost his parents at a young age, Alen fought to put himself through higher education. He is bright and has the courage that makes a stack scientist exemplary.

David Makalu

David Makalu

Assistant Scientist

NDip Chem Eng

David is gentle and his words are well considered. He is methodical in his stack testing work and he provides great support to Khumbu In our Johannesburg team.

Bertus Bonthuys

Bertus Bonthuys

General Manager

BSc Mech Eng

Bertus is a great leader! As General Manager he oversees the team, assists key clients, and maintains the high energy environment and client-centric approach that we feel characterises Yellow Tree.

Luka Mayekiso

Luka Mayekiso

Lead Scientist

NDip Chem Eng

Luka is our bright new star! His energy, charisma and outstanding communication make him an asset on site where conditions can be tough and optimism is essential. We are so grateful to have him in the team!

Thanushri Pather

Thanushri Pather

Commercial Manager

BSc Chem Eng

Nush’s energy is contagious. As our Commercial Manager, she engages with clients to establish their needs and to issue proposals. She also seeks out new business and is a technical sounding board.

Sean Charteris

Sean Charteris

Managing Director

PR Chem Eng

Sean is a professionally registered Chemical Engineer with a wealth of experience in combustion, energy generation and industrial emissions. He is passionate about the environment and loves people.

Ray Slinger

Ray Slinger

Operations Manager

BSc Environmental Science

Ray is effervescently joyful. As Operations Manager, he manages Yellow Tree’s three stack testing teams and health & safety. They say that one should lead with the heart of a servant, and serve with the heart of a king. That is Ray!

Caitlin Morris

Caitlin Morris

Environmental Engineer

BSc Chem Eng, LLM in progress

Cait is a superb chemical engineer! She is incredibly bright and her work is flawlessly accurate. Cait has extensive knowledge of the legislation and air pollution abatement. She writes superb reports and helps our clients.

Khumbu Badantswana

Khumbu Badantswana

Lead Scientist

NDip Chem Eng

Khumbu is our genius. He is the first to solve a problem when testing a boiler or process stack. His quietness belies his confidence and his friendliness. We are blessed to have him head up our Johannesburg team.

Sakhumzi Baliso

Sakhumzi Baliso

Lab and QC Manager

NDip Analytical Chemistry

Sakie is one of our best! With years of emissions testing experience, he now oversees our laboratory, our field equipment and adherence to US EPA methods. His smile is contagious and lights up the room!

Mdu Mpikwa

Mdu Mpikwa

Assistant Scientist

NDip Chem Eng

Mdu faces the toughest stack testing circumstances with a smile and a steady hand. Even the most challenging 12 hour day can not get him down. He is an asset to our team, and a delight to work with.

Peter Frost

Peter Frost

Engineer

Mechatronics Engineering

Peter has bucketloads of energy! He is in his final year of Mechatronics Engineering at UCT. At Yellow Tree he is working on a zero-emissions electric tuk tuk project. We are so excited that he has joined our team.

Monique

Monique

Admin, Health, and Safety

NDip Health and Safety

Monique is passionate about safety and about protecting the people that work at Yellow Tree. She has always protected others and placed the needs of others above her own. She is loyal and kind and we are excited about her future.

NLA Certified

We are certified with the National Laboratory Association of South Africa. This ensures that we are accredited to test your stack emissions. If you would like to learn more, visit the NLA website here.