Sabesp - Lagoon WWTP Upgrade Case Study

Sabesp is a Brazilian water and waste management company owned by São Paulo state. It is the largest waste management company in the world by market capitalization, providing water services to 26.7 million residential, commercial and industrial users in São Paulo and in 363 of the 645 municipalities in São Paulo State. It provides basic sanitation services, which include all phases (abstraction, treatment, processing, distribution), and the collection, treatment and reuse of sewage. A significant proportion of the Wastewater Treatment Plants (WWTPs) operated by Sabesp are designed for secondary treatment only. Recently the State of Sao Paulo has suffered from water shortages, as a response to this crisis the government has introduced new, stricter legislation to protect receiving water bodies. As a result, it will be necessary to upgrade many existing lagoons to achieve tertiary treatment standards.

Solution

Sabesp was intrigued by the potential of the Membrane Aerated Biofilm Reactor (MABR), a ground-breaking technology for the aerobic biological treatment of wastewater, as a drop-in solution to existing tanks and in particular lagoons. The MABR system can increase capacity and achieve simultaneous nitrification and denitrification while at the same time reduce energy demand. In particular, the flexibility of deploying the MABR as a standalone system or directly into an existing lagoon or Activated Sludge tank, along with the high removal rates that can be achieved, make it an ideal technology for upgrading a WWTP.

In 2016 Sabesp, The Dow Chemical Company and OxyMem began a collaboration to test the potential of using an MABR to upgrade an existing lagoon from secondary treatment only to tertiary treatment. Aruja plant located near São Paulo Brazil was selected as the test location. This plant is designed for secondary treatment only and meets all its current requirements. The MABR was seen as an ideal technology for any future potential upgrades.

The OxyMem MABR has been demonstrated as a robust, flexible, compact, low sludge production and low energy system. The MABR installed in Aruja achieved high COD loading and removal rates when operated in drop-in mode. This makes the OxyMem MABR system ideally suited for upgrading existing plants to increase their capacity or those that need to be upgraded to achieve a higher effluent quality. The MABR units can be “dropped” directly into existing tanks to instantaneously increase capacity without the need for onsite civil work.

When operated in biofilm mode the MABR system achieved a very high effluent standard. Particularly impressive was the very low effluent TSS concentrations achieved without any additional solids separation device. The high effluent quality and low energy use, (with an SAE of 15 kg O2/kWh possible with high-efficiency blower), combined with a compact biological tank and no separate settler makes the MABR system an ideal financially competitive and technically proven solution for greenfield applications.