Water and wastewater processes: the last (and next) 30 years
TASEEM is searching for a new waste disposal contractor. Just by thinking it, she asks her iCan to show her who would pay the best price for her family’s excretions. While she studies the options – with or without food waste, daily or weekly collection – she pops a capsule of coffee and another of water into the espresso machine. The nanoscopically-thin algal skins of the capsules dissolve as the temperature rises and Taseem savours the aroma. She checks the news headlines for 22 March. It’s World Water Day and there has been a further slight but patchy improvement in access to clean water supplies in the Global South, sometimes called the “Fourth World”, the First World now being the walled enclaves of the mega-rich.
As convenor of IChemE’s Water Special Interest Group (SIG), Taseem is well aware that this slow rate of change has persisted throughout its 60-year history, while technology has made astonishing advances alongside enormous geopolitical shifts. Taseem asks the iCan to display WET News 30, an archived Millennium edition of the SIG’s publication, and reads a piece from the then chairman.
Present day: how we got here
Just 17 years on since that piece, in this, the SIG’s 30th anniversary year, CDs, CDROMs and DVDs, while still common, have been superseded by high-speed digital downloads and streaming. Mobile phones are not only powerful computers but highly sophisticated navigation aids and a tool for immediate dissemination of information – and regrettably, also fake news and abuse.
In the first 30 years of the SIG, we have witnessed wide-ranging developments in water and wastewater treatment.
- One clear and obvious driver of water and wastewater process development has been legislation. The EC Directive on drinking water quality – enacted in 1989 in England and Wales – required water supplies to be improved, mainly for natural colour, iron and manganese, nitrate, lead, and pesticides; and the EC Urban Wastewater Treatment Directive 1991 and Water Framework Directive 2000 brought in more stringent standards for coastal sewage treatment and for nitrogen and phosphorus removal from inland discharges.
- The cryptosporidiosis outbreaks in Oxford, UK and Milwaukee, US, naturally led to great interest in treatment solutions, to complement catchment controls. As chlorination at practical levels was ineffective, a consistently high degree of particle removal was required and, once UK regulations had been amended to allow it, UV could also be used to further reduce risk and expensive monitoring requirements.
- Reports of terrible disease from high arsenic levels in water supply wells in India and Bangladesh led to a great deal of work on alternative treatments in the early 2000s.
- The rising cost of energy and the search for green power has been another major driver of treatment process and sewage sludge disposal choices. In particular, anaerobic digestion of sludge has been enhanced by hydrolysis pretreatments to increase the conversion of organics to methane.
- Membranes have become mainstream in drinking water and industrial water treatment, and have found valuable applications in wastewater treatment, particularly where space is tight or land is at a premium.
- The rising cost of water following water services privatisation in England and Wales, and water scarcity in many parts of the world, have increased interest in industrial water management and re-use, and in grey water supply.
- Doubling of the cost of phosphate has prompted the viable recovery of phosphorus from sewage sludge.
- The rapid development of computing has affected the water industry just like any other, giving us excellent and customisable process visualisation for operation and maintenance; easily programmable controllers; intelligent instrumentation; automation, telemetry and management reports; powerful modelling; and data mining tools.