The ECs 1991 directive on wastewater quality has far-reaching implications. By the end of the year 2000, every town with a sewage load equivalent to 15,000 or more people must be equipped with a waste water treatment plant. By 2005 this requirement will extend to villages with more than 2,000 inhabitants.
The resulting growth in the number of small wastewater treatment plants raises challenges for the instruments used to monitor the quality of the water entering and leaving the plants. Quantities to be monitored include nitrogen compounds, phosphorus, suspended solids and the loading of organic substances - measured as total organic carbon (TOC), biological oxygen demand (BOD) and chemical oxygen demand (COD).
Existing monitors for organics, nitrogen, phosphorus and other contaminants in industrial wastewater and municipal sewage are bulky and expensive. The partners in this project set out to build a simpler, cheaper analyzer suitable for small treatment plants.
A French University led the project with support from a French spectrophotometer manufacturer and Universities in the Balearic Islands and Greece. The instrument they developed uses a newly-designed ultra-violet spectrophotometer and some innovative techniques for wet chemical analysis.
The instrument developed is now available on a commercial scale. It can be used accurately with or without calibration, and because the detector is small and the deconvolution algorithms are relatively simple, the spectrophotometer needs only a standard microprocessor to run it.