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Solving the sewage and sanitation crisis through innovation

Submitted by on 28 Sep 2015 – 09:05

Tackling present and future water-related problems certainly requires out of box ideas and unconventional thinking. UNESCO-IHE has developed a number of innovative products concerning education, technology and capacity development. Prof. Dr. Damir Brdjanovic, Professor of Sanitary Engineering at UNESCO-IHE Institute for Water Education writes about innovations in wastewater, sewage and urban sanitation

IMG_q4912 The first innovations in urban sanitation were made by the Romans and Ancient Greeks (800 BC to 500 AD). After the “Sanitary dark ages” (450 and 1750 AD), in about 1800, a collection system appeared in many cities, and around 1900, Liernur came up with a system to collect toilet water through a vacuum sewer.

At the end of 18th century, the first sewage treatment technologies using micro-organisms, gradually began to emerge; and exactly one century ago the first activated sludge plant was built based on the invention of Ardern and Lockett. Initially, while the focus was on the removal of organic matter (C) from sewage, in the second half of the 20th century a new problem with surface water emerged: that of eutrophication, and treatment requirements were extended to nitrogen (N) and phosphorus (P). Different nitrogen removal systems were developed by Ludzack and Ettinger (1962) and Wurhmann (1964), combined by Barnard into one system in 1972.

After the accidental discovery of biological phosphorus removal by Srinath (1959), Levin and Shapiro invented a basic treatment configuration in 1965, which served as inspiration to other engineers to develop new system configurations for combined C, N and P removal. The energy crisis in the 1970s, associated with an increased demand for industrial wastewater treatment, shifted attention from aerobic to anaerobic wastewater treatment, resulting in the development of the up flow anaerobic sludge blanket reactors (UASB) by Lettinga in 1980.

Around the turn of the last century, with ever increasing treatment requirements, the need arose to upgrade and retrofit treatment plants. This has led to a range of new processes being integrated in existing treatment plants, such as SHARON, ANAMMOX and BABE processes for improved nitrogen removal, and mineral crystallization processes for phosphorus precipitation for phosphorus recovery and reuse. Recent attempts to intensify the separation process by membrane separation of the sludge have been successful and the number of plants with this so-called MBR technology is on the rise [1].

A different type of process was invented by the group of van Loosdrecht (2005), who engineered microbial structures to allow micro organisms to form a stable, well-settling, granules instead of fluffy flocks of sludge. Sewage treatment by activated sludge is a technology that continuously evolves and allows for recycling and reuse of resources such as water, energy and chemicals. Phosphate recovery from sewage is increasingly being applied, and other options for the recuperation of valuable materials from sludge are also emerging, e.g., the production of bio- polymers and bio-plastic and the recovery of cellulose fibres [1].

With an increasing global population demanding more resources, new opportunities for the conversion of existing plants from classic ‘removal-type systems’ towards ‘resource-recovery systems’ and ‘energy-factories’ are becoming increasingly available. Potable water shortage and further increase in coastal population worldwide are shifting attention to the use of alternative, secondary quality water resources in urban water cycle, such as seawater for toilet flushing, which triggered development of SANI process for saline sewage treatment by the group of Chen (2009); a novel process which makes use of sulphate (S) present in seawater. In contrast to high-income industrialized countries, where coverage by sewage facilities is high and practically all wastewater is treated at an advanced level, the sewerage coverage and sewage treatment in less developed countries are overall very low. In these regions, centralized conventional activated sludge systems are competing with decentralized approaches. The solutions for less developed regions may be the construction of smaller and simpler, decentralized systems that are community-managed, thus minimizing costs or enhancing resource recovery [1].

The example of Windhoek Goreangab in Namibia confirms that advanced treatment technology, combined with proper governance, can be successfully applied in the less developed world. Widespread adoption of modern technology, e.g. mobile telephony, and the fact that most currently less developed regions now have an economic and technical level well above those in Europe and the United States a century ago (when the latter started developing their sanitation systems), are encouraging.

Enormous pressure on sanitation experts
It is also the fact that the sanitation needs of 2.7 billion people worldwide are served by onsite sanitation technologies, and that number is expected to grow to 5 billion by 2030 [2]. This places enormous pressure on sanitation professionals to come up with “out of the box” thinking, business as unusual approaches, a change of paradigms, and inventive and unconventional solutions. These in turn lead to the translation of inventions into innovative products, services, processes and new activities that are introduced to the real world [3].

Stimulating innovation
The recent boost of innovations for pro-poor sanitation is partially the result of the Bill & Melinda Gates Foundation’s Water Sanitation and Hygiene programme, which has emphasized the strategic importance of improving faecal sludge management globally, by supporting institutions and facilitating application of inventions in the field.

Undoubtedly, there is a wealth of innovations at different stages of implementation readiness, rapidly becoming available concerning centralized sewage treatment and in particular in situ faecal sludge management. For a new generation of young scientists, engineers and other professionals entering the sanitation field, the quantity, complexity and diversity of these new developments can be overwhelming, particularly in less developed countries, where access to courses and training materials is not readily available [4].

Therefore the development and implementation of innovative, trans-disciplinary and holistic educational and training approaches, including distance, student-centered, problem-based learning and state-of-the art training materials, are essential, so the issues can be embraced with deeper insight, advanced knowledge and greater confidence.

[1] Van Loosdrecht M.C.M. and Brdjanovic D. (2014). Anticipating the next century of wastewater treatment. Science. 344(6191):1452-1453
[2] Strande L., Ronteltap M., Brdjanovic D. Ed. (2014) Faecal Sludge Management: System Approach for Implementation and Operation. IWA Publishing, pg. 500. ISBN 9781780404721
[3] Brdjanovic D., Ed. (2015) Innovations for Water and Development, UNESCO-IHE, pg. 60. ISBN 9789073445314
[4] Henze M., van Loosdrecht M.C.M., Ekama G.A. and Brdjanovic D. Ed. (2008) Biological Wastewater Treatment: Principles, Design and Modelling. IWA Publishing, pg. 511. ISBN 9781843391883.