THE ÁGUA DOCE PROGRAM

THE ÁGUA DOCE PROGRAM (PAD) USES DESALINATION TECHNOLOGY TO PROVIDE QUALITY WATER TO RURAL COMMUNITIES IN THE SEMI-ARID REGION OF NORTHEASTERN BRAZIL

By Dr. Emilio Gabbrielli

The Água Doce Program (PAD) is an initiative of the Federal Government of Brazil, which is coordinated by the Ministry of Regional Development in partnership with federal, state, municipal and civil society institutions. It aims at establishing a permanent public policy of access to quality water for human consumption in the Brazilian semi-arid region through desalination systems using reverse osmosis technology.

This region, which spans over 10 of the 27 States of Brazil, is characterized by thousands of sparse low-income rural communities, some founded by escaping slaves hundreds of years ago. The groundwater, which is the main source of water, is brackish and salinities found cover the whole spectrum of brackish water up to values in the range of sea water. Due to geological characteristics, the production capacity of deep wells is small. In most cases it is just enough to produce water for personal consumption, cooking and bathing of infants.

The PAD has proven incredibly successful and resilient. It has already achieved having 811 plants in operation serving 320,000 people. Unless delays occur due to the Covid-19 pandemic, it aims at reaching the landmark figure of 1000 operating plants by the end of the current year. This success is against all odds given the disadvantaged context, the high level of analphabetism and limitations of local government. The

key to success has been some key differentials which have meant strong social mobilization and buy-in. management of the desalination systems, with effective participation by communities and representatives of municipalities, states and the federal government. In each community, “shared management agreements” are built and signed. These instruments define the management responsibilities of the parties, with the key responsibility resting with the community itself. The capital investment for the plant and its periodic maintenance, including chemical analysis of raw water and permeate, comes from the Federal Government, but the cost of running the plant on a day to day bases has to be met by the community.

Another differential of the PAD is the environmentally appropriate destination of the effluent generated in the desalination process. Whenever possible, depending on the physical and chemical characteristics of the concentrate, this is taken advantage of for other uses such as animal feed, growing fish of the Tilapia species and irrigation for biosaline agriculture. Crops produced are normally of Atriplex Nummularia, which is used as fodder to grow sheep and goats. When reuse is not possible, which is not frequent, the effluent is released into a containment tank for evaporation, preventing soil degradation.

There are ten agreements in execution, one for each one of the States of the Brazilian semi-arid region, with an investment of approximately R$ 260 million (around US$ 50 million) to supply quality water to 1,200 communities. Since the beginning of implementation, 3,378 communities in 270 of the most critical municipalities were diagnosed. Approximately 2,400 operators, all from the communities to be served, were trained.

The desalination systems built so far have an installed capacity to produce around 3.2 million liters of drinking water per day. Considering the minimum reference

flow rate of a deep well of the PAD, which is approximately 1,000 l/h and is typical of a large part of the wells located in the Brazilian semi-arid region, a system has normally the potential to produce safely 4,000 l/day of desalinated water according to a day-time production schedule established. The recovery is always kept low to minimize use of pretreatment and the risk of fouling of the membranes. This amount allows one well to supply 400 people with 10 l/day of drinking water per person.

The biggest challenge has been to secure continuous supply of electric power, both because of unreliability of supply and its cost. With a view to overcome it, the PAD has started introducing the use of solar energy to feed the desalination systems. The first pilot project using photovoltaic panels has been implemented in the municipality of João Câmara, Rio Grande do Norte, followed by a few more. The 2020-2025 work plan includes an ambitious program to introduce solar energy in many other plants. 1500 photovoltaic solar systems are expected to be installed to serve the PAD desalination plants.

About

The IDA acknowledged the success and contribution of the PAD with a Presidential Award at the IDA World Congress in São Paulo, Brazil, in 2017. The PAD was also recognized as an initiative which adopts an integrated approach to sustainable development and fight to poverty in a parallel event to the UN Economic and Social Council held in New York in May

2017.

the Author

Emilio Gabbrielli h a s a d e g r e e i n C h e m i c a l E n g i n e e r i n g ( 1 9 7 2 ) a n d a P o s t - D e g r e e C e r t i f i c a t e ( 1 9 7 3 ) f r o m t h e B o l o g n a U n i v e r s i t y , I t a l y . H e h a s 4 5 y e a r s ’ w o r l d w i d e e x p e r i e n c e i n w a t e r a n d i s n o w o p e r a t i n g a s a n i n d e p e n d e n t c o n s u l t a n t. H i s m a i n a r e a s o f e x p e r t i s e a r e d e s a l i n a t i o n a n d r e u s e a n d w a t e r u t i l i t i e s . B e t w e e n 2 0 0 3 a n d 2 0 0 8 h e w a s t h e C E O o f t h e G l o b a l W a t e r P a r t n e r s h i p , t h e I G O p r o m o t i n g s u s t a i n a b l e m a n a g e m e n t o f w a t e r r e s o u r c e s . H e h a s s e r v e d t h e I D A a s a d i r e c t o r f o r s e v e r a l t e r m s a n d a s P r e s i d e n t i n 2 0 1 5 - 2 0 1 7. H e i s a m e m b e r o f t h e I D A H o n o r a r y C o u n c i l a n d V P o f t h e I D A F o u n d a t i o n . H e i s a n H o n o r a r y G l o b a l A m b a s s a d o r o f t h e A u s t r a l i a n W a t e r A s s o c i a t i o n .