Anaerobic digestion for wastewater treatment in Mexico: State of the technology

Due to the nascent wastewater treatment practice in Mexico there is great o pportunity to introduce anaerobic digestion as the core of the wastewater t reatment processes. Nevertheless, this requires an understanding of all the technical, economical and financial aspects that limit its development. Ac cording to the National Water Commission, in 1995 municipal and industrial wastewater were produced at rates of 232 and 168 m(3) s(-1) respectively, b ut only 20 and 12% of these volumes were treated, often with very low effic iencies. In order to increase the treatment capacity of the country, approx imately US$ 4515 million managed by the banks for development are supposed to be available to invest in environmental projects. Other financing mechan isms exist through treasury incentives and penalties. Within this situation , anaerobic digestion has grown although not at the required rate and bigge r investments are being made on conventional aerobic and physicochemical te chnologies. Presently there are in the country 85 anaerobic wastewater trea tment plants treating 216,295 m(3) d(-1) with an installed volume of 228,55 1 m(3). UASB reactors account for 74% of the installed volume and national companies have supplied 76% to the anaerobic market. Proper integration of the anaerobic digestion processes for water recycling and energy recovery h as not been achieved and there is a big need to demonstrate economic and ec ological sustainability. (C) 2000 Elsevier Science Ltd. All rights reserved .