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Water reuse technologies in the Brazilian Semiarid region: Interview with George Lambais

For a long time, the population of the Brazilian Semiarid region has been practicing water reuse to deal with the irregularity of rainfall in the area. However, this reuse is not always done safely, especially for those who use these systems, and often there are gaps in data regarding the quality of the reused water. It is within this scenario that the multidisciplinary project for the improvement of the Graywater Reuse System by Dual Filtration intends to contribute.

With the participation of social organizations, universities, government agencies, and the third sector, the project aims to promote, safely, sanitation and quality reused water sources for agroecological production of families in the semiarid region. The System is one of several technologies that treats graywater – that used in household tasks at home, except for toilet water – and redirects it for the family’s agroecological production.

In an exclusive interview, INSA researcher George Lambais highlights the different phases of the project and comments on the advances in monitoring the systems that are serving 9 families today in three different regions of the state of Paraíba. A biologist with a master’s degree in Plant Physiology and Biochemistry and a PhD in Chemistry in Agriculture and Environment, Lambais emphasizes that the project has been seeking not only to validate the technology but also to gather robust data to support effective rural sanitation public policies. The logistical and communication challenges also indicate the complexity and scope of this initiative, which advances beyond the technical issue to encompass an expanded vision of community health and well-being.

How did your involvement with graywater reuse technologies begin?

I have been at the National Semiarid Institute (INSA) since 2016, completing 8 years in July. My coming to INSA was not only for research but also for the structuring of laboratories here. When I arrived, the institution was in a moment of setting up the laboratories. Thus, I was responsible for the structuring of the Environmental Microbiology laboratory, which was one of the first at INSA to operate through the implementation of specific methodologies in this area. Along with it, I was allocated as a researcher in the water resources nucleus and, when I arrived in the sector, we were at the beginning of a project with reuse technology. That’s where this trajectory began.

There are different graywater reuse technologies, right?

Yes. This first technology we were studying – and which is now called SARA – Environmental Sanitation and Water Reuse – involved the reuse of raw sewage for agricultural purposes. In 2017, we started monitoring the SARA technology, and by 2018, we already had a consistent base of results pointing to treatment efficiency. Until the end of 2018, we worked with the monitoring of reuse systems in the rural area of the municipality of Cubati, in Paraíba. Monthly, we collected water and evaluated the system’s performance mainly in the removal of pathogenic bacteria, such as Escherichia coli, which is an important indicator, both for drinking water and for reuse water. In parallel with this SARA technology, we also started working on monitoring the Bioagua technology. We took advantage of being in the same location where there were these two types of systems and started this monitoring. I classify this as a first major stage of the work.

What are the differences between these two types of water treatment systems?

With SARA, we worked with the total reuse of household water, including wastewater. And the other system, Bioagua, is a methodology for graywater reuse, meaning all household water except toilet water. Another difference is that SARA consists of an anaerobic reactor with a polishing pond, which allows it to treat all the family’s sewage. On the other hand, Bioagua involves physical and biological filtration of graywater through the composition of this treatment system. The reuse system we are currently working on with WTT, INSA, Patac, and other organizations is an adaptation of Bioagua, which we are calling Dual Filtration.

Dual Filtration Water Reuse System installed in the Benefício territory, in the municipality of Esperança (Paraíba). Photo: Camelo/ASP-TA Território da Borborema


How did you arrive at this Dual Filtration system that is being developed today with WTT and other partners?

In 2019, we met WTT at an event in São Paulo, and since then, we have been discussing research and technologies in the area of rural sanitation in the Brazilian semiarid region. Since then, they challenged us to gather information about reuse technologies available in the literature to seek validation and scaling. At this stage of the project (2022), the technology survey conducted by INSA researchers, Mateus Mayer and Rodrigo Barbosa, both colleagues from the Water Resources Center, was crucial. They dedicated themselves to this initial stage of literature review of available and published technologies to identify some promising technologies for experimentation with WTT. We went to the Santa Rosa Quilombo, in Boa Vista, Paraíba, already within this project with WTT, and monitored three reuse technologies for six months. Of these three, the Dual Filtration system had the best performance. The technology proved to be very promising; the water had no odor, and there was a significant reduction in the amount of E. coli, which is an important pathogen indicator. In summary, all monitored variables had excellent results for this technology.

What is the difference between the types of reuse water?

Basically, we have the classification of restricted and unrestricted reuse, based on WHO regulations for irrigation in agriculture. Unrestricted reuse is for any crop, including raw food consumed. However, the water must be of excellent quality. On the other hand, restricted-use water is only for fruit and forage crops with development well above ground level. Our goal in the project is to ensure that the treatment system delivers water of sufficient quality for unrestricted reuse.

And after the success of the Dual Filtration technology was verified, what was the next step?

How many families are being monitored today? The quality of water treated by the Dual Filtration System was very good, reaching the level required for unrestricted reuse. However, we had only two systems installed in the families being analyzed. And two families with very different graywater generation dynamics. So the question arose: Will this result be repeated in a larger number of families? Here, phase two of the project ends, and we start phase three: we increase the sample universe and continue with only one technology, Dual Filtration. Today, we have 9 families under monitoring. In addition to these systems we were already monitoring in Boa Vista, systems were also installed in rural areas of Campina Grande and the municipality of Esperança. In March 2024, we started biweekly monitoring. We want to see how the technology works on a larger scale, even to start thinking in terms of public policies. Before, we could say that the technology was promising, but we couldn’t go much beyond that because there were only two families. Now we will have a robust database with the increase in the number of installed systems.


Before and after the filtration systems. The water is destined for agroecological production. Photo: George Lambais


What is this monitoring showing?

In these initial data, we have a good overall picture. We can say that around 70% of the systems are operating as expected, delivering good quality water. The systems installed in some families have parameters close to what we want but still need some adjustments. Others already have numbers very close to what we aim to achieve. It’s normal to see initial variation, but then the trend is to stabilize, which is happening. Therefore, it’s important to continue monitoring to see the evolution. The systems built in Campina Grande are doing very well, and in Esperança, the results are also promising. There are two systems that we need to observe more carefully and understand what is happening – whether it’s a management problem or if the system isn’t functioning properly. We have never had such a robust database in water reuse projects here in the laboratory, both in terms of data and images. And that’s important, for example, to speak with the producers, with social organizations. This is already a segue to my next question: it’s a project with a lot of science, a lot of data, but also a lot of fieldwork and practical experience. We’re talking about a social technology.

What about the contact and exchanges established within this project?

This is very interesting. I came from academia, from a Ph.D., academic publications. And just by being here at INSA, I entered a different universe. Here, our research is different, it’s on the frontline. You’re there with the producer. I had to learn to speak differently so that the information could be absorbed. It’s a challenge for researchers coming from academia. A very important point is the relationship we also have with social organizations: we learn from them, and they learn from us too. But it was a challenge because this is also a project that always has feedback. When a phase ends, we have a feedback moment with the farmers, and also to listen to their experience, what worked, what needs to improve. This is very interesting because it’s not, for example, a project that ends with the publication of a paper. In addition, we also have training sessions with farmers. An extremely important point that we have been discussing is the issue of system management by families, mainly regarding the grease trap. And the issues of system care take into account also the equal division of labor, adaptation of heavy system components (e.g., grease trap cover), among others. The project grows with the stages and always together with the farmers.

How do you see the perspective of this project expanding into public policy?

That’s also very interesting. Over the course of the project, we began to think bigger. WTT brought us a significant challenge: how are we going to think about public policy down the line? We want to scale this technology, but for that, we need to have security. To reach a scale comparable, for example, to the One Million Cisterns Program, this security is necessary, but how are we going to organize ourselves for that? What will be our foundation? So, this already aligns with the next steps of the project. By August, we should finish the monitoring, and from that, we’ll have a robust and solid database. We’ll have an academic step, which is also important with publications resulting from this research. There’s also this discussion about this technology being part of the National Rural Sanitation Plan, the PNSR. That would be the grand finale. It’s a dream, for sure. That rural sanitation comes out of the drawer, and that this technology joins several others existing in the Brazilian semiarid region.

Rural Sanitation and Water Reuse Seminar held by the National Semiarid Articulation (ASA) in April, in Pau dos Ferros (Rio Grande do Norte). Photo: Education and Communication Axis of the Regional Institute of Small Appropriated Agriculture (IRPAA)

One important aspect of some WTT projects is the coordination of a special team that complements and guides itself towards solving a diagnosed challenge. How is this scenario of coordination with different actors in the reuse project?

I believe that when WTT, social organizations, INSA, and academia came together, we had a very good “league” in the project. It’s a highly multidisciplinary project: we have biologists, sanitary engineers, agronomists, journalists, and many other professionals from various fields of knowledge. We put together a very good team. And that’s how we’re also expanding our horizons. Initially, for example, our relationship with social organizations was only with PATAC. Today, to work in other territories, we’re also in dialogue with CENTRAC, Folia, COLETIVO, Polo da Borborema… This is very interesting. It’s also worth highlighting the resource provided by WTT. This support that WTT brings to a new project allows us to operate differently, more independently. It’s something we think about for the laboratories themselves – that we can make them run more self-sufficiently in financial terms.

This coordination at different levels is very interesting, but a project like this also brings challenges. What challenges do you highlight in this journey?

Working with a large and multidisciplinary team, one of the challenges will always be communication. The “blocks” of the project are interconnected, so we have to be well organized. But we overcome this, and I believe we overcome it because we have engaged people who are giving extra energy to make things work.

Another major challenge is logistics. And when we talk about monitoring, which is the stage we are in now, logistics are the major hindrance: you have to go to the field, collect, return, analyze. For example: in this monitoring we are doing now, from the moment we collect the water, we have 24 hours to perform microbiological analyses. After that, it is no longer valid for E. coli analysis, for example. That’s why, initially, we debated a lot about how we would do this. At the beginning of the project, there was also talk of including other states like Pernambuco, Rio Grande do Norte, and Ceará. But with this logistical issue, it was not possible. I believe that, in order to set up projects that require adequate microbiological monitoring, it is necessary to think very well about the logistical issue and who will perform the analysis. This is another point: to understand who can perform these analyzes, who can compose a network of laboratories to give more breadth to projects like this. It’s complex because it involves a lot of people, but if we are thinking ahead to public policy, we have to think about it too. Another challenge is calling on health and social service professionals to join the project because we are expanding our information base. We want to know about family health after the implementation of this technology. It is important to have this network view of the project, thinking in a structured and connected way, not only about water issues but also about health and other aspects. It is a reuse project, yes, but we are also dealing with sanitation, promoting health.

What is the importance of a water reuse project for the Semiarid region?

There are two main points. Such a project is extremely important for the Semiarid region because we are talking about sanitation, and sanitation is health. If we are promoting sanitation, we are promoting public health. And in rural areas, this impact is even more significant. With a reuse project, we are collecting and treating families’ sewage and consequently generating a water source that they would not have available for agricultural use. The second issue that is very important in the Semiarid region, for sure, is the production of new water sources. With reuse, we have water with nutrients too, making fertigation possible, i.e., irrigation and fertilization of plants. The numbers are not very high, but this contribution to the type of soil found in the region, which is usually nutritionally poorer in some locations, is already important. It’s like a fertilizer along with water. It’s a water source that the family didn’t have. Or sometimes they had it, but inappropriately, with contamination risks. Reuse has been done here in the Semiarid region for a long time, but often without safety. What we’re doing is improving something that was already being done and promoting technologies that can guarantee water and food security in family farming properties.