Sewage and Waste Water Treatment
Removal of contaminants, micro-organisms, and any other type of pollutant in huge volumes of wastewater before pumping it in rivers, streams and oceans prevents damage to environment and also greatly helps in preservation of water sources.
With the increase in scarcity of water, we can say that wastewater in an untapped resource. Today’s technological developments allow us to realize this and offer advanced wastewater treatment processes.

Membrane Bio Reactor

Application

The Membrane Bio Reactor (MBR) process is a process for treating sewage and industrial waste water using air and bacteria. Waste waters contain organic material and this is measured by the Bio-chemical Oxygen demand (BOD) and Chemical Oxygen Demand (COD) of the waste water and the MBR process is used to bring down the level of BOD and COD in the waste water for further use or for discharge. The MBR process is a combination of micro or ultrafiltration Membranes with a suspended growth bio-reactor thus enabling operation at high levels of bio-mass in the Mixed liquor (typically in the range of 11000 to 12000 mg/l). Hence the MBR generally require less space than an activated sludge process (ASP) because the biomass is highly concentrated. Also the outlet quality due to a physical membrane separation process results in a much better quality of effluent compared to the conventional ASP. There are two designs of MBRs’ – an internal submerged design and an external side-stream design. The membrane configurations are flat sheet or hollow fiber.

Operation

Submerged / Internal

The membrane modules are installed in either the main bioreactor vessel or in a separate tank. The membranes can be flat sheet or tubular, and can incorporate an online backwash system which reduces membrane surface fouling by pumping membrane permeate back through the membrane. Where the membranes are in a separate tank to the bioreactor, individual trains of membranes can be isolated to undertake cleaning regimes incorporating membrane soaks, however the biomass must be continuously pumped back to the main reactor to limit MLSS concentration increase. Air scouring of the membranes is also done to reduce fouling. Where the membranes are installed in the main reactor, membrane modules are removed from the vessel and transferred to an offline cleaning tank.

Sidestream / External

The filtration elements are installed outside the reactor. The biomass is either pumped directly through a number of membrane modules and back to the bioreactor, or the biomass is pumped to a bank of modules, from which a second pump circulates the biomass through the modules. Cleaning and soaking of the membranes can be done in place with use of an installed cleaning tank, pump and pipework.