Innovative Phosphorus Removal Technologies

Water eutrophication caused by excess nutrient loading from human activities has been recognized as one of the major water quality issues for several decades (1, 2). The World Resources Institute has identified 415 hypoxic coastal zones in the world. The situation is even more alarming for freshwater resources with 54% of lakes in Asia, 53% in Europe, 48% in North America, 41% in South America and 30% in Africa being identified as eutrophic (3).

Although some environments are more greatly influenced by changing levels of nitrogen, addition of just 1 g of phosphorus promotes the growth of up to 100 g algae, and as such, represents the principal trigger of eutrophication and toxic blue-green algae blooms.

The Effect of Algae Blooms

These blooms can decrease the oxygen levels in the waters, resulting in fish kills and reduced biodiversity. They can also cause foul odors and tastes, diminishing the recreational appeal of the waters or their potential for use as a water supply source. Some species have even been found to release chemicals that are toxic to animals and humans.

Sources of Phosphorus Pollution

Given the magnitude of eutrophication worldwide, solutions for reducing phosphorus loading from municipal, agricultural, industrial, urban and rural point and nonpoint sources have been sought worldwide. While point source pollution is definable and thus controllable, nonpoint (diffuse) pollution originates from a variety of run-off sources, and consequently, controlling this type of contamination is even more complex, requiring an integration of technological, socio-economical and educational factors.

Methods of Phosphorus Removal

Methods for phosphorus removal from wastewaters and storm water runoff have emerged over the past few years. However, the current absence of the governmental regulations for phosphorus discharge limits, coupled with the extremely high costs of environmental technologies verification (ETV) programs impose insurmountable obstacles in phosphorus removal technologies applications.

Current Regulatory Framework

Despite the recognized need for phosphorus reduction worldwide (2-5), the current regulatory framework for attenuation of this type of contamination has been extremely limited. Phosphorus discharge criteria have been developed only for municipal wastewater treatment facilities (MWTF) and, in a very few developed countries. Moreover, the current phosphorus removal methods (either chemical or biological) used in MWWTF are complex, extremely expensive, consume large amounts of energy and generate large volumes of sludge that then must be appropriately disposed of (5).

Phosphorus discharge criteria for other point and nonpoint pollution sources (agricultural, industrial, or residential onsite wastewater treatment systems (septic systems)), are not included in the current wastewater regulations. This situation is extremely alarming given the exponential growth of population, livestock and food production. For example, 30-40% of the population in developed countries rely on septic systems consisting of a septic tank and a drain field. A hundred years ago, soil drain fields were considered natural adsorbing materials for phosphorus. However, the phosphorus retention capacity of any adsorbing material is finite and once it’s reached, the material needs to be replaced. The situation is much more disturbing in developing countries, where peri-urban settlements are not approved by the local and national governments. As a result, many rivers in third world cities are being used as large open sewers.

The lack of regulatory framework greatly diminishes funding and the aspiration for scientific advancements for phosphorus removal technologies. While there has been a growing interest in investigations on phosphorus sorbing materials that could be used in onsite wastewater treatment systems, this research has been mainly performed in university laboratories, while field testing and applications remain limited to the efforts by a very few scientist in Sweden and United States (6).

The Road From Innovations to Applications

The biggest obstacle to any environmental technology application is in the current costs and the time required by the Federal Environmental Technology Verification (ETV) Programs. In the United States for example, the costs range from $120-140,000 per application, lasting 24-36 months. This means that a small business such is PhosphoReduc would have to invest a minimum of $360,000 to obtain ETV certification for the 3 types of wastewater, e.g. municipal, residential and agricultural effluents treatment.

Individual State Permits do not require such large financial investments during the review process, however the process is also extremely lengthy, lasting 24-30 months from the moment of application. Moreover, as phosphorus discharge limits currently do not exist in the regulatory framework, most of the water governmental agencies either reject applications or require intensive permitting processes, consisting of two different permit types: one for beneficial use of water filtration material and the other for general use of technology. Each of the two permit processes require intensive water quality monitoring by accredited laboratories, thus an investment of at least $85-100,000. And without certifications it is impossible to implement systems and bring water quality improvements.

PhosphoReduc Innovative Technologies

Background

I have dedicated over 20 years of my professional life to research and development of sustainable technologies for phosphorus pollution prevention and control. During my doctoral research at the University of Edinburgh, UK, in the early 1990s, I have pioneered the research on use of various iron, aluminum and calcium based materials natural and industrial by-products that can be used as phosphorus sorbing materials in onsite treatment systems.

As Research Professor at the University of Vermont, and the director of the University Constructed Wetlands Research Center (CWRC), along with my research team we have developed several suites of sustainable wastewater treatment technologies including:

1. Integrated (multistage) constructed wetlands and phosphorus removal filter systems
2. Phosphorus removal and sequestration “PRS-101” filters for the treatment of agricultural, municipal and residential wastewaters (point pollution sources)
3. Simple “torpedo” filter systems for agricultural tile drain and urban storm water outflows (for capturing and treating phosphorus and solids pollution originating from nonpoint, diffuse pollution sources (Figure 1).

These treatment technologies are efficient not only in phosphorus removal, but also in other pollutants reduction, including nitrogen, organic matter and suspended solids, pathogens and various metals and minerals. In addition, we have also shown that once the lifespan of the filter system is completed, the phosphorus retained by the filtration material can be re-used, instead of chemical fertilizer, to enhance soils used for agriculture, horticulture and forestry.

In 2008, I applied for the Agricultural Innovation Fund to the University of Vermont College of Agriculture and Life Sciences and the Office for Technology Transfer (UVM TTO). I was awarded the seed start-up funding that enabled me to establish my business PhosphoReduc LLC (http://phosphoreduc.com/). The seed funding also provided necessary funding for patent applications. We currently have patents pending for the two of our technologies, one for phosphorus removal from point pollution sources and the other for phosphorus removal from agricultural and urban drain outflows.

Our filtration systems are passive systems consisting of one or more filter units filled with iron (Fe) and/or calcium (Ca) based filtration material, modified steel slag, a recyclable by-product from the steel industry. The filtration media is packed, arranged and engaged with one another in specially-designed modules so as to form a modular composite filter, according to the method developed by PhopshoReduc LLC.

Applications

To date, we have demonstrated that PhosphoReduc filter systems reduce phosphorous, suspended solids and pathogens (E. coli) loads from sewage, agricultural and urban point and nonpoint pollution sources by 70 – 100 percent by systems implemented in a variety of climatic regions, on 4 continents.

The examples of Phosphoreduc applications include:

1. Agricultural Runoff Treatment:

• a simple cartridge system installed to reduce phosphorus and solids from agricultural tile drains collecting water from 30 acres in Vermont achieved reductions averaging 72% and 75%, respectively (Figure 1). Currently, there is no agricultural practice designed to reduce phosphorus loading from agricultural tile drains. We have showed that phosphorus concentrations measured in 6 different agricultural drains over 10 spring storm events exceeded critical 0.1-0.2 mg/L P concentrations for incipient eutrophication in each rain event.
• feed bunks (silage leachate) runoff treatment, known as one of the most toxic waste streams on farms. Currently, the vegetative treatment area (practice code 635) is the major “best management practice” recommended by the US Natural Resources Conservation Service (NRCS) and widely implemented to treat silage leachate runoff on farms in the US (7). While it cannot achieve more than 20% phosphorus reduction efficiency, the current cost of this practice implementation is in order of $15,220 per acre. The results from a 2 year investigation by our research team has shown that the implementation of an innovative “treatment train” consisting of a PhosphoReduc filter, and a vegetative trench could achieve up to 90% phosphorus reduction at half the cost of the currently recommended 635 practice (8).

2. Urban Stormwater Treatment

• PhosphoReduc filter installed in Columbus, OH to treat a golf-course stormwater pond achieved an average of 85% reduction efficiency. Several follow up installations are planned in 2012.

3. Sewage Treatment

• PhosphoReduc filter has been implemented in southern Taiwan to test system efficacy in sewage wastewater treatment originating from the university student residences. This system showed nearly 100% reductions in dissolved and total phosphorus and suspended solids over 10 months of investigation (9).
• Following successful treatment in Taiwan, two filter installations are currently planned to reduce phosphorus loading originating from a mixed sewage and urban runoff effluent and causing eutrophication of Tubarao lagoons in Vitoria State, Brazil.

The Future of Innovative Phosphorus Removal Technologies

Despite all of the above obstacles, during the past two years PhosphoReduc technologies started to gain interest among governmental agencies in the US and internationally. We have contributed to eutrophication prevention and water quality improvements in over 40 laboratory, pilot, demonstration and full scale projects across 5 continents (Europe, North America, South America, Asia, New Zealand). In Sweden, professor Gunno Renman developed polonite based systems for phosphorus removal from residential septic systems. However, polonite filtration material is made from the natural calcium rich material found only in Poland, which restricts systems applications beyond these two countries.

In any future research and development of Phosphorus removal technologies we ought to keep in mind the fact that as a key component of fertilizers, phosphorus is fundamental for the world’s food supplies, and an irreplaceable and essential element of life with its sole source as phosphate-bearing rocks (10-11).

Phosphorus resources are non-renewable with global reserves estimated to reach their peak in the next 50-100 years (10). The current rate of phosphate extraction is reported at 167 million tonnes per year with a growing demand that accounts for a 2% annual increase. With continuing decline of global phosphate reserves, the impacts are likely be immense, particularly in terms of rising food prices, growing food insecurity and widening inequalities between developed and developing countries (10-11).

Thus, not only should we continue research, development and implementation of phosphorus removal technologies but we have to invent the ways of phosphorus re-use as a soil amendment in agriculture, forestry, acid mine reclamation and horticulture. Sweden is the first country in the world that has established regulatory requirement to recycle phosphorus from municipal wastewater treatment effluents by 2016. It enabled professor Renman and I to start developing processes for phosphorus re-use from our phosphorus removal treatment systems.

References

1. Ryther, J.H. and Dunstan, W. M. (1971). Nitrogen, Phosphorus and Eutrophication in Coastal Marine Environments. Science 171: 1008-1013.
2. Conley, D.J., Paerl, H.W., Howarth, R.W., Boesch, D.F., Seitzinger, S.P., Havens, K.E., Lancelot, C. and Likens, G.E. (2009). Constrolling Eutrophication: Nitrogen and Phosphorus. Science 323: 1014-1015.
3. World Resources Institute (2012). Eutrophication and Hypoxia: Nutrient Pollution in Coastal Waters. url: http://www.wri.org/project/eutrophication
4. US EPA (2012). Water: Pollution Prevention and Control.
5. Jiang, F., Beck, M.B., Cummings, R.G., Rowles, K. and Russell, D. (2005). Estimation of Costs of Phosphorus Removal in wastewater Treatment Facilities: Adaptation of Existing Facilities. Water Policy Working Paper #2005-011.
6. Westholm, Johansson, L., Drizo, A. and Renman, G. (2011). The Use of Blast Furnace and Electric Arc Furnace Steel Slag in Water Pollution Control. Ferrous Slag - Resource Development for an Environmentally Sustainable World. EUROSLAG Publication No.5. pp 103-11.
7. USDA NRCS (2008). Vegetative Treatment Area Practice 635. USDA, Natural Resources Conservation Service―Practice Code 635. url: https://www.nrcs.usda.gov/
8. Drizo, A., Liang, K. and Gorres, J. (2011). Phosphorus and E.Coli Reduction from Silage Leachate via Innovative PhosphoReduc Filtration. Final Report to the Conservation Innovations Grants Program, submitted December 2011. University of Vermont Grant Agreement Number : 69-3A75-9-121.
9. AUTM, the Association of University Technology Managers (2011). Academic Filtration Innovations Aim to Solve What Ails a Perishable Resource: Water. Published in the 2011 Edition of a Better World Report. Respond, Recover, Restructure: Technologies Helping the World in the Face of Adversity, pp 78-83.
10. The Broker (2009). Peak Phosphorus- The next inconvenient truth. The Broker online 15, August 2009. 
11. Yoshida, H., van Dijk, K., Drizo, A., Vanginkel, S., Matsubae, K. and Buehrer , M. (2011). Chapter 6: Phosphorus Recovery and Reuse. In: Dijk, K. and Yoshida, H. (ed.). Phosphorus, Food and Our Future. Frontiers in Life Sciences. In review.