Wastewater Lagoon Systems

Wastewater Lagoon Systems

This blog was written by Gregory Hinds.

Sustainable Wastewater Management in Latin America: Failures, Successes, and New Strategies

On February 20th, 2015, Dr. Stewart Oakley, Professor in the Department of Civil Engineering at California State University, Chico visited the University of South Florida to deliver a talk entitled “Sustainable Wastewater Management in Latin America: Failures, Successes, and New Strategies”, at the Environmental and Water Resources Engineering Seminar. This blog displays background information and significant conclusions elucidated by Dr. Stewart Oakley’s talk. Dr. Oakley’s PowerPoint presentation, packed full of information and images related to wastewater management in Latin America, can be seen here. Additional information contained in this blog is taken directly from an article published by Dr. Oakley in Small Flows Quarterly, Spring 2005, entitled “Lessons Learned from Latin America: A Case Study on the use of Wastewater Stabilization Ponds in Honduras”, which can be seen here. 

Background Information

  • Worldwide approximately 1.1 billion people lack access to improved water sources.
  • Approximately 2.4 billion people have no access to any form of improved sanitation.
  • Excreted-related infections are a major cause of morbidity and mortality worldwide.
  • There are approximately 4 billion cases of diarrhea each year, causing 2.2 million deaths, mostly among children, from diseases associated with lack of safe drinking water, inadequate sanitation, and poor hygiene.
  • Intestinal worms (helminths) infect at least 10 percent of the population of the developing world and likely infect up to 24 percent of the world’s population.
  • Protozoan infections probably exhibit a similar prevalence to helminths, and Entamoeba histolytica infection is one of the 10 most common infections in the world.
  • Lack of wastewater treatment is a health hazard in all developing countries. With the exception of the U.S., Canada, and some European countries, the median percentage of urban wastewater treated worldwide is very low.
  • The discharge of untreated wastewater is especially a health hazard where receiving waters are used for drinking water sources, bathing, washing, irrigation, and fisheries.
  • Conventional wastewater treatment methods as practiced in the U.S. and Europe are not affordable in developing countries (which is the main reason why they don’t exist), nor do they necessarily provide the requisite degree of pathogen removal for the protection of public health, especially parasitic infections.

“Those whose job is to select and design appropriate systems for the collection and treatment of sewage in developing countries must bear in mind that European and North American practices do not represent the zenith of scientific achievement, nor are they the product of a logical and rational design process. Rather, treatment practices in the developed countries are the product of history, a history that started about 100 years ago… Conventional sewage works were originally developed in order to prevent gross organic pollution in European and North American rivers; they were never intended to achieve high removal of excreted pathogens. Their use in tropical countries in which excreted infections are endemic is only justifiable in special circumstances, for there is an alternative treatment process much superior in obtaining low survivals of excreted pathogens—the waste stabilization pond system.” Feachem, R. G., D. J. Bradley, H., H. Garelick, and D. D. Mara. 1983. Sanitation and Disease; Health Aspects of Excreta and Wastewater Management. J. Wiley & Sons. New York.

Conclusions

  • Mechanized wastewater treatment in Latin America is not a sustainable solution: in nearly every case where mechanized wastewater treatment such as activated sludge has been implemented in Latin America, especially in rural communities, the plants have been abandoned or are not functioning as designed, resulting in minimal treatment and very costly power bills.
  • The use of raw and partially treated wastewater for agricultural irrigation is a threat not only to public health in Latin America, but to the health of individuals worldwide who are consuming crops imported from Latin American countries.
  • Wastewater stabilization pond systems are the most appropriate technology for wastewater treatment in Latin America. They have been shown to reliably meet World Health Organization guidelines for effluent reuse in agriculture.
  • Lack of wastewater treatment in Latin America is significantly contributing to the rapid degradation of aquatic ecosystems, both coastal and inland. Of particular concern are inland lakes within heavily populated watershed such as Lake Amatitlán, Guatemala, Lake Atitlán, Guatemala, and Lake Titicaca, Bolivia/Perú.
  • Traditional nutrient removal methods, as practiced in the US and Europe, is not a viable approach for protecting aquatic ecosystems in Latin America from cultural eutrophication.
  • Land application of treated wastewater allowing nutrient uptake by plants is the only sustainable approach to protecting aquatic ecosystems in Latin America, but this must be coupled with sustainable wastewater treatment to protect public health (e.g. stabilization pond systems).
  • Export of wastewater from densely populated lake basins is the ideal solution for protecting aquatic ecosystems. This has been demonstrated by successful projects carried out around the world, including at Lake Tahoe, California/Nevada, where millions of gallons of wastewater are exported daily to a reservoir and eventually reused for irrigation in the Carson Valley, Nevada.
  • In many cases, such as the cases of Lake Atitlán, Guatemala and Lake Titicaca, Bolivia/Perú, energy recovery through the installation of hydroelectric turbines powered by falling wastewater outside of the lake basin can cover electricity requirements for pumping the wastewater out of the lake basin.
  • The recovery of energy from wastewater through the incorporation of covered anaerobic lagoons in wastewater stabilization pond systems offers another substantial source of energy/revenue to improve the sustainability of wastewater management within Latin America.
  • The use of well-designed wastewater stabilization pond systems in Latin America, in conjunction with adequate performance monitoring and appropriate desludging frequency, offers potential to recover water and nutrients from wastewater with minimal threat to public health.
  • The recovery of water and nutrients from wastewater in Latin America offers great potential to decrease water stress, improve crop yields, offset environmental impacts associated with inorganic fertilizer production and distribution, and improve the sustainability of wastewater management in Latin America.

“It makes little sense to argue over technological details and removal efficiencies if the municipalities themselves do not have the infrastructure and the financial capabilities to adequately operate, plan for expansion, and desludge their systems. Latin America has historically had serious problems making drinking water systems sustainable, and the median ratio of urban drinking water tariff to unit cost of production is less than one for the Region. If there is difficulty in making drinking water systems sustainable, it is obvious that wastewater treatment will be even more formidable a task. It is for this reason that waste stabilization pond systems integrated with agricultural or aquaculture reuse offer the best promise to help address some of this hemisphere’s most serious public health problems.” Stewart Oakley. 2005. A Case Study of the Use of Wastewater Stabilization Ponds in Honduras. Small Flows Quarterly, Vol 6 No. 2, pp. 36—51, Spring 2005.

 

Now that you are familiar with lagoon systems in Latin America, this week’s video features a potential system in Michigan.

Watch the video here:http://youtu.be/Dfd1E_4JDB0

Answer the following questions based on the video, reading and powerpoint presentation:

  1. What strategies could we use to engage with decision makers in Latin America (see blog) or the US on the opportunities available with resource recovery from wastewater management, with a special focus on lagoon systems? Consider end users in your discussion when you consider who the decision makers are in this scenario.
  2. What funding sources may be available for the implementation of resource recovery facilities, particularly lagoon systems, in vulnerable locations such as Lake Atitlán, Guatemala and communities like Belding, Michigan? Think of any out of the box approaches that you know of where you somehow contribute to the funding through your own purchasing of certain products.
  3. How would you improve this video?

This is the blog for week 9 of the Spring 2015 “Reclaim Is…” seminar.

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