Submerged Aerated Fixed Films (SAFF) Technology

One of the cost-effective methods of waste water treatment and sewage management that is primarily used in residential and commercial complexes is Submerged Aerobic Fixed Film Reactor (SAFF). It technology is part of sewage treatment plant (STP). This technology mainly has three stages that are Primary Settlement, Secondary Treatment and Final Settlement / Clarification.

Primary Settlement: Here, larger solids get settled at the bottom of the primary tank and are removed periodically as sludge. Other buoyant material which floats upwards are usually removed by a scraping/screening method.

Secondary Treatment: Where the biodegradable Organic Matter is degraded by the biomass on the SAFF media.

Final Settlement / Clarification: Where degraded solids are settled out of the biologically treated effluent.

Submerged Aerated Fixed Films (SAFF) technology is a process used to reduce the organic loading of residential and commercial sewage / waste water. The process works towards the reduction of Biological Oxygen Demand (BOD) and a significant quantity of Suspended Solids (SS) which if otherwise untreated would contaminate river and other water outlets. In simple words, SAFF process is used to substantially improve effluent discharge quality. 

In the wastewater industry, SAFF Technology is seen as the simple and cost-effective method of commercial and residential sewage sanitation/waste water treatment, particularly for small to medium sized treatment plants where available land is limited, and where full time operational manning would be uneconomical. A well designed Submerged Aerated Filter plant has no moving parts within its process zones, any serviceable items will be positioned to access easily without disrupting the ongoing treatment.

Advantages

i)              Deep reactors enabling small space requirements

ii)             No sludge re-circulation is required to maintain MLSS as in the case of conventional aeration system.

iii)           Can be designed to any size to deal with larger flow and loads.

iv)           Modular design allows easy installation.

v)            Use of fine bubble diffused aeration generally reduces the energy requirements as compared to surface aerators.

vi)           Ability to effectively treat dilute domestic wastewater.

vii)          Low & stabilized sludge production eliminating the need for sludge digestion.

viii)         Higher loading of BOD on the media enables to reduce the aeration tank size. SAFF requires 25-40% lesser tank volume as compared to activated sludge process.

ix)           SAFF process able to achieve 95-98% BOD reduction.

x)            High MLSS – Less Space required for the treatment.

xi)           Less susceptible to upsets due to flow variations.

xii)          SAFF supports low sludge generation, low Odour and low visual impact.

xiii)         Maintenance requirements are simple.

   

Disadvantages

i)              High reliance on external energy input.

ii)             Clogging of reactor due to absence of primary sedimentation.

iii)           Requires skilled manpower.

iv)           Reliance on proprietary filter media.