As a part of a massive expansion plan for Chhatrapati Shivaji International Airport located in Mumbai, India, a wastewater recycle project was contracted in 2011 to cater to the growing requirements of the expanded airport.

Due to increasingly strict environmental regulations, the treatment of raw sewage wastewater is required before it is allowed to flow into the natural ecological system. As the airport has a lack of fresh water availability for its needs, it now recycles and reuses the treated sewage water for its operations, such as toilet flushing, horticulture, and HVAC cooling makeup water.

One unique and challenging aspect of the wastewater recycle plant project was that the plant must cover a very limited footprint in order to accommodate all needed components of the airport expansion project. The plant successfully met this small footprint requirement due to innovative engineering designs. QUA’s Q-SEP modules successfully fit the plant’s requirements due to their large surface area and high operating efficiency. The ultrafiltration system follows a Sequencing Batch Reactor (SBR) process and precedes a reverse osmosis treatment system for tertiary treatment. The feed and treated water quality analysis is shown below.

Location: Mumbai International Airport, Mumbai, India
Product: Q-SEP 6008
Capacity: 3 x 440 gpm (3 x 100 m³/hr)
UF Product Water: Turbidity < 0.04 NTU, SDI < 3
Application: Sewage Wastewater Recycle

Feed Water Quality
pH 6.7 – 8.1
Turbidity (NTU) Variable Up To 12
TDS (mg/l) 700
BOD (mg/l) < 20
COD (mg/l) < 60
Temp Design Max 250
UF Treated Water Quality
Flow Rate (3 Total Trains) 1320 gpm (300 m³/hr)
Turbidity (NTU) < 0.04
SDI15 <3

Process Flow Diagram

UF Solution

MIAL evaluated both UF and conventional media filtration for pretreatment to their RO system. Since the water feeding the pretreatment system was sewage wastewater, the pretreatment step needed to be designed to handle variable water qualities and extremely high turbidity levels. This required careful consideration and planning to assure the right equipment was selected.

The primary goal of the RO pretreatment system was to reduce the silt density index (SDI) and turbidity of the water feeding the RO to a point where RO cleaning would be minimized. Media filtration was unable to meet this requirement so MIAL focused their evaluation of several UF membrane suppliers.

Ultrafiltration was selected as the pretreatment of choice to the RO plant. QUA’s Q-SEP was specifically chosen as the ultrafiltration solution for the MIAL project due to its high water quality output compared to other UF membrane suppliers. The ultrafiltration system consists of three trains operating at a flow rate of 440 gpm each and with a backwash flux of 200 l/m2/hr. The chemical enhanced backwash (CEB) is designed to use sodium hypochlorite, sodium hydroxide and hydrochloric acid. The backwash and CEB system is common for all the UF streams.