While most scientific articles about MBR systems suggest membrane surface fouling as being the main operational limitation for the technology, it is widely recognised by practitioners that clogging phenomena – possibly related to inefficient pre-treatment – are at least as important. It is also recognised that clogging takes different forms...
This feature summarises recent research into a new membrane bioreactor technology applied for water reuse (NEWater, Singapore) with reference to energy demand. Reducing aeration demand for membrane air scouring combined with a high flux has been shown to significantly reduce energy demand.
Biological nitrogen removal from wastewater typically happens through aerobic nitrification (from ammonia to nitrate) and anoxic denitrification (nitrate to nitrogen gas). This is usually carried out in two separate process tanks other than in a sequencing batch reactors (SBRs). However, it is more energetically efficient to convert ammonia directly to nitrogen gas, since it requires less oxygen.
The non-Newtonian nature of sewage sludge means that its measured viscosity µs varies with shear rate due to the shear-dependent deformation of the flocculant solids (Yang et al, 2009). Viscosity affects the shear at the membrane interface, shear being a key parameter in promoting flux, and the dependency of apparent viscosity on temperature may then also be significant in determining flux.
Aquaculture is the fastest growing agriculture worldwide, supplying a substantial amount of seafood consumed today. The ‘recirculating aquaculture system’ (RAS) is an upcoming production system in intensive fish production, where over 90% of the water is recycled for production of live feed, larvae and fry and on-growing fish.
The Arenales del Sol WWTP in Spain combines biological treatment with nutrient removal with a submerged MBR system fitted with flat sheet (FS) ultrafiltration membranes, with an average treatment capacity of 10,000 m3/d (10 MLD). The plant provides high quality treatment to highly variable seasonal sewage inflow due to the nature of this popular coastal region.