DRI researchers successfully remove harmful hormones from Las Vegas wastewater using green algae

DRI researchers successfully remove harmful hormones from Las Vegas wastewater using green algae

Xuelian Bai, Ph.D., Assistant Research Professor of Environmental Sciences, works with an algae sample in the Environmental Engineering Laboratory at the Desert Research Institute in Las Vegas. Credit: Sachiko Sueki.


 

LAS VEGAS, Nev. (April 8, 2019) – A common species of freshwater green algae is capable of removing certain endocrine disrupting chemicals (EDCs) from wastewater, according to new research from the Desert Research Institute (DRI) in Las Vegas.

EDCs are natural hormones and can also be found in many plastics and pharmaceuticals. They are known to be harmful to wildlife, and to humans in large concentrations, resulting in negative health effects such as lowered fertility and increased incidence of certain cancers. They have been found in trace amounts (parts per trillion to parts per billion) in treated wastewater, and also have been detected in water samples collected from Lake Mead.

In a new study published in the journal Environmental Pollution, DRI researchers Xuelian Bai, Ph.D., and Kumud Acharya, Ph.D., explore the potential for use of a species of freshwater green algae called Nannochloris to remove EDCs from treated wastewater.

“This type of algae is very commonly found in any freshwater ecosystem around the world, but its potential for use in wastewater treatment hadn’t been studied extensively,” explained Bai, lead author and Assistant Research Professor of environmental sciences with the Division of Hydrologic Sciences at DRI. “We wanted to explore whether this species might be a good candidate for use in an algal pond or constructed wetland to help remove wastewater contaminants.”

Samples of Nannochloris grow in the Environmental Engineering Laboratory at DRI. This species of green algae was found to be capable of removing certain types of endocrine disrupting chemicals from treated wastewater. Credit: Xuelian Bai/DRI.

Samples of Nannochloris grow in the Environmental Engineering Laboratory at DRI. This species of green algae was found to be capable of removing certain types of endocrine disrupting chemicals from treated wastewater. Credit: Xuelian Bai/DRI.

During a seven-day laboratory experiment, the researchers grew Nannochloris algal cultures in two types of treated wastewater effluents collected from the Clark County Water Reclamation District in Las Vegas, and measured changes in the concentration of seven common EDCs.

In wastewater samples that had been treated using an ultrafiltration technique, the researchers found that the algae grew rapidly and significantly improved the removal rate of three EDCs (17β-estradiol, 17α-ethinylestradiol and salicylic acid), with approximately 60 percent of each contaminant removed over the course of seven days. In wastewater that had been treated using ozonation, the algae did not grow as well and had no significant impact on EDC concentrations.

One of the EDCs examined in the study, triclosan, disappeared completely from the ultrafiltration water after seven days, and only 38 percent remained in the ozonation water after seven days – but this happened regardless of the presence of algae, and was attributed to breakdown by photolysis (exposure to light).

“Use of algae for removing heavy metals and other inorganic contaminants have been extensively studied in the past, but for removing organic pollutants has just started,” said Acharya, Interim Vice President for Research and Executive Director of Hydrologic Sciences at DRI. “Our research shows both some of the potential and also some of the limitations for using Nannochloris to remove EDCs from wastewater.”

Although these tests took place under laboratory conditions, a previous study by Bai and Acharya that published in November 2018 in the journal Environmental Science and Pollution Research examined the impacts of these same seven EDCs on quagga mussels (Dreissena bugensis) collected from Lake Mead. Their results showed that several of the EDCs (testosterone, bisphenol A, triclosan, and salicylic acid) were accumulating in the body tissues of the mussels.

Researcher examines a sample of quagga mussels collected from Lake Mead. A recent study by Bai and Acharya found that endocrine disrupting chemicals are accumulating in the body tissues of these mussels. Credit: Xuelian Bai.

Researcher examines a sample of quagga mussels collected from Lake Mead. A recent study by Bai and Acharya found that endocrine disrupting chemicals are accumulating in the body tissues of these mussels. Credit: Xuelian Bai.

“Algae sit at the base of the food web, thereby providing food for organisms in higher trophic levels such as quagga mussels and other zooplantkons,” Bai said. “Our study clearly shows that there is potential for these contaminants to biomagnify, or build up at higher levels of the food chain in the aquatic ecosystem.”

Bai is now working on a new study looking for antibiotic resistance in genes collected from the Las Vegas Wash, as well as a study of microplastics in the Las Vegas Wash and Lake Mead. Although Las Vegas’s treated wastewater meets Clean Water Act standards, Bai hopes that her research will draw public attention to the fact that treated wastewater is not 100 percent clean, and will also be helpful to utility managers as they develop new ways to remove untreated contaminants from wastewater prior to release.

“Most wastewater treatment plants are not designed to remove these unregulated contaminants in lower concentrations, but we know they may cause health effects to aquatic species and even humans, in large concentrations,” Bai said. “This is concerning in places where wastewater is recycled for use in agriculture or released back into drinking water sources.”

Bai’s research was funded by the Desert Research Institute Maki Endowment, the U.S. Geological Survey, and the Nevada Water Resources Research Institute. The studies mentioned in this release are available from Environmental Pollution and Environmental Science and Pollution Research journals:

Bai, X. and Kumud Acharya. 2019. Removal of seven endocrine disrupting chemicals (EDCs) from municipal wastewater effluents by a freshwater green alga. Environmental Pollution. 247: 534-540. Available: https://www.sciencedirect.com/science/article/pii/S0269749118347894

Bai, X. and Kumud Acharya. 2018. Uptake of endocrine-disrupting chemicals by quagga mussels (Dreissena bugensis) in an urban-impacted aquatic ecosystem. Environmental Science and Pollution Research. 26: 250-258. Available: https://link.springer.com/article/10.1007/s11356-018-3320-4

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The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI serves as one of eight institutions in the Nevada System of Higher Education.

Meet Erick Bandala, Ph.D.

Meet Erick Bandala, Ph.D.

Erick Bandala, Ph.D., is an assistant research professor of environmental science with the Division of Hydrologic Sciences at the Desert Research Institute in Las Vegas. Erick specializes in research related to water quality and water treatment, including the use of nanomaterials in developing new water treatment technologies. He is originally from Mexico, and holds a bachelor’s degree in chemical engineering from Veracruz State University, a master’s degree in organic chemistry from Morelos State University, and a Ph.D. in Engineering from the National Autonomous University of Mexico. Erick has been a member of the DRI community since 2016, when he moved to Las Vegas to begin his current job. In his free time, Erick says that he enjoys doing nothing – a passion that is not shared by his wife of nearly 30 years, who enjoys doing many things.


DRI: What do you do here at DRI?

EB: My work here is to develop advanced technologies for water treatment, such as processes that can deal with the pollutants in the water that are not removed by conventional water treatment methods.

DRI: We understand that a lot of your work involves nanomaterials. What are nanomaterials, and how do you use them in your research?

EB: Nanomaterials are materials that are so small that if you compare the size of one of these materials with a basketball, it’s like comparing the size of the basketball with the size of the earth. These nano-sized materials have applications in many different fields.

In my case, what I’m doing with the nanomaterials is using them to promote reactions in the water that can produce chemical species capable of destroying contaminants. Not only to remove the contaminants, but to destroy them from the water.

Erick Bandala, Ph.D. at work in DRI's Environmental Engineering Lab. Credit: Dave Becker, Nevada Momentum.

Erick Bandala, Ph.D. at work in DRI’s Environmental Engineering Lab. Credit: Dave Becker, Nevada Momentum.

 

DRI: What type of contaminants do you hope to remove? Can you tell us about one of your projects? 

EB: Right now, we are trying to get nanoparticles made of something called zerovalent iron, which is iron with no charge on it. We are planning to use this to remove antibiotics from water. As you know, we all use antibiotics every now and then. And when you use them, the antibiotics get into your body and you will probably only use about 15 percent of the total amount that is present. Whatever remains is discarded with your feces or urine into the wastewater.

Once the wastewater arrives at the water treatment plant, the conventional water treatment processes will probably not be able to remove the antibiotic. So, the antibiotic passes through the wastewater treatment system and keeps going with the treated effluent. In the case of Las Vegas for example, it goes back to Lake Mead. This is a problem, because we are learning now that bacteria can become resistant to antibiotics just by exposure – and when bacteria in the environment become resistant to the antibiotics, there is no way for people to treat infections.

So, in our work, we hope to use nanoparticles to destroy the contaminants in the wastewater. At the moment we are just running some trials in the lab, but we eventually hope to run the experiment at pilot level to see if we can treat wastewater coming back from plants to the lake, and ensure that we will not have these contaminants going back to our environment.

Another part of my research is on how to use solar energy to remove contaminants from water. This way you can save some money by using an energy source that is common in Nevada, widely available. We have a lot of sunshine here.

Information about nanomaterials from DRI's Environmental Engineering Lab. Credit: Dave Becker, Nevada Momentum.

Information about nanomaterials from DRI’s Environmental Engineering Lab. Credit: Dave Becker, Nevada Momentum.

 

DRI: How did you become interested in working on water treatment and water quality?

EB: My very first job was working in a research institute in Mexico that was devoted entirely to water. The group that I arrived to work with was dealing with water quality and treatment in wastewater and drinking water. So, I started down this path just because it was available and I needed the job – but my plan was to spent two years working on this and now it has been more than 25 years. I feel very passionate about this field of work. I feel like this is the way that I have to try to help people, and I love it.

DRI: You are originally from Mexico. What brought you to DRI?

EB: When the position at DRI opened three years ago, I started learning about the water related issues that Nevada and particularly Las Vegas was facing, and was fascinated. The city gets its water supply from Lake Mead then sends treated wastewater back to the lake — so having almost 100 percent recycling of the water is something that caught my attention immediately. Not only because it’s wonderful, but that it may also result in other problems like the recycling of some pollutants that you probably don’t want in your drinking water. That idea really captured me. So I decided to apply for the job, and have had three years of great fun trying to deal all of those problems and promote some solutions that may help to deal with the reality we’re facing in Las Vegas. Reno is not that different – we all need water when we’re living in places where water resources are so scarce. I was really intrigued by how to deal with all of these problems and how I might help.

Erick Bandala (second from left) and his colleagues from DRI's Environmental Engineering Lab. 

Erick Bandala (second from left) and his colleagues from DRI’s Environmental Engineering Lab.

 


For more information about Erick and his research, please visit: https://www.dri.edu/directory/5205-erick-bandala