Abstract:
The geographical location and the specific geological and weather conditions of Canary Islands archipelago have promoted the development of complex facilities and installations focused on water desalination and wastewater reuse. The artificial water cycle strongly depends on membrane technologies and therefore, research made in canary’s universities have taken a significant relevance in the last 20 years.
In this framework, membrane technologies for seawater desalination have been extensively applied in several of the Canary Islands, especially the Easter ones. In addition, membrane bioreactor and ultrafiltration membranes as advanced treatment, have been implemented in order to accomplish the high restrictive guidelines and laws for water reuse irrigation.
The research Group on Treatment and Water Reuse (TyRA in Spanish) from ULL has been involved and lead the main research project carried out about membrane ultrafiltration application at lab and pilot plant scale. The principal aims of these studies have been focused on membrane fouling characterization and its possible mitigation.
Recently, we have operated an anaerobic immersed hollow fiber membrane bioreactor under psychrophilic conditions at pilot scale feeding with domestic wastewater. In this study, a new module configuration of rotating membrane was successfully tested at highly fouling conditions. Nowadays, this module is being essayed for its possible application as a harvesting method of biomass developed in photomembrane bioreactors. The continuous and intermittent rotation as turbulence promoter will be compared in order to establish the advantage and disadvantages of the turbulences on biomass fractioning and fouling capacity.
the other hand, membrane bioreactor as tertiary treatment from old plants with poor performance by secondary clarifiers has been also studied. These old plants usually produce effluents with high ammonium contents compromising their secure discharge into water bodies and for irrigation purposes. In this sense, it must be noted that agriculture is a high water demanding sector and the water reuse system implemented in Tenerife island in 1993 depends on a closed pipeline of more than 60 km, where sulfide is developed. The partial nitrification results in an interesting way to avoid sulfate reduction and also a way to supply nitrate to crops. These studies provided the basis for the development of a new mode of operation of conventional membrane filtration in MBR, under not temporized cycles. In this mode filtration time is dynamic as a function of transmembrane pressure pre-fixed, a set-point to establish the level of allowed fouling.
