El Ser

Articulo 1
Reuse of treated water by membrane bioreactor (MBR)
Abstract
It shows an overview and update of the use of membrane bioreactors (MBR) to obtain purified water suitable for reuse. Whereas the existing rules, we compare the physicochemical and biological quality of the effluent from these systems in relation to more conventional treatments. Considering the suitabilityof the MBR technology to kill pathogens, has paid particular attention to the disinfection process and the mechanisms that govern it. The results show water quality MBR treated with equal or superior to that obtained with conventional treatment (activated sludge supplemented with tertiary treatment for disinfection by the addition of bactericides.)
Keywords:
Activates sludge, membrane bioreactor (MBR), waterreuse, disinfection, treated water, regenerated water, fouling.
Introduction
Currently, the use of treated water from wastewater treatment plants (WWTP) is a promising solution to the problem of lack of water resources faced by many countries. However, it is necessary to consider the possible risks that could lead to their use to regulate their field of use and quality required. Therefore, it isimportant to establish standard limits of the various chemical and biological parameters to be controlled.
In 1991, the European economic community develop a policy for the collection, treatment and discharge of urban sewage and some industrial sectors, which already contemplated the possibility of reuse of treated water whenever appropriate. In 2000, the European Union met and adapts differentpolicies and established the legislative framework in the field of water policy. Guidelines were established based on physicochemical parameters, biological and hydro morphological to ensure water quality. From this directive, countries like Spain and Italy have drafted their own legislation, which set out the quality criteria for reclaimed water use by applications.
Specifically, in Spain, the RD1620/2007 provides treated water to five types of different uses: urban, agricultural, industrial, recreational and environmental. It defines the limit values ​​of quality parameters and criteria to mark the Spanish legislation in terms of water use.
Similarly, in the United States Environmental Protection Agency (EPA) drafted in 2004 the Guidelines for Water Reuse (EPA/625/R-04/108), which outlinesthe different risks, the potential uses of water from stations purification and quality criteria in each state.
In this sense, the World Health Organization (WHO) presented a guide for 4 years in the recommended limit values ​​for a number of biological parameters (bacteria, viruses, nematodes, etc.) Ensure that there is no risk health by reusing treated water. Due to the limits set by law andtaking into account the quality of treated water leaving the secondary treatment and the inclusion of tertiary treatment to obtain water that can be reused.
MBR technology
Among the various processes that have been developed in recent years to achieve the quality required for reuse of water, membrane bioreactor MBR special interest due to the combined action of the reactor biological treatmentand membrane filtration.Depending on the pore size of the separation process in the membrane is accomplished by microfilm (MF) and ultrafiltration (UF).
This technology is similar to conventional activated sludge system with the difference that the solid / liquid separation is performed by membrane filtration and not by sedimentation in a secondary clarifier.
There are two different systemsdepending on their configuration: external membrane bioreactor, in which the membrane module is outside the reactor and submerged membrane bioreactor, in which the module is immersed in a reactor biological or annex into a tank.
The main advantages of an MBR system compared to conventional activated sludge systems are:
• Need to lower reactor volume due to the higher concentration of mixed liquor...