It has been a long day for Kevin Quinn, chief executive of Chemical Solutions Group (CSG), a low-profile, family-owned business which, over four decades, has quietly grown into a specialist supplier to the potable water, wastewater, environmental and hygiene sectors in Ireland — and, more recently, Britain. It is Tuesday evening, and the company, which employs 100 people in Shannon and Foynes and generates annual revenues of €65 million, has just closed its first significant acquisition since Quinn joined the firm in 2023. The target was Celtic Water Solutions, a business founded in 2000 by John O’Connor that counts more…