24/10/2011 - WORKSHOP #3 EMERGING TECHNOLOGIES AND NEW CHALLENGES IN WASTE WATER RESEARCH

ABSTRACTS  

Future needs and trends in waste water purification – Willy Verstraete

Zero Waste Water: Short-cycling of wastewater resources for sustainable cities of the future

We currently experience a set of societal waves towards wellness, organic food and bio-economy, all relying on increasing water demands. Remarkably, the International Water Association notes that water is still not recognized as a priority in terms of planetary boundary conditions, although our current footprint for water surpasses the carrying capacity of the earth with a factor 5.

The old water cycle is schematized and the fact that at present some 2.6 billion people still have no decent sanitation emphasizes the need for a totally new water cycle approach, both at the decentralized and the centralized level.

The ‘zero waste water‘ approach water is possible and is mainly based on the forefront integration of anaerobic digestion. The various techniques to achieve maximum recovery of energy, mineral nutrients, and ‘NEWater‘ as such, are illustrated. Their economic and ecological putative impacts are indicated.

Academic research in waste water purification - Willy Baeyens

 How to achieve a better water quality?

-       Reduce the emissions of pollutants into the environment. Adequate monitoring of the quality status of the receiving waters allows judging the efficiency of the measures and standards in force.

-       Improve the techniques of waste water treatment. Although many of those techniques exist since many years their efficiency is not always very high.

-       Search for the most appropriate solution when a complex polluted water system has to be tackled.

On the hand of a few representative cases, the benefits and caveats of water protection and water treatment systems are discussed from an academic point of view.

How membrane technology creates new opportunities in future water research – Ivo Vankelecom

Recent developments in membrane technology, at the level of enhancing the membrane performances as well as at process level, open up new possibilities in water research. A number of them, in which COK has been involved, will be highlighted.

Membrane bioreactors will be discussed first, in their well-known aerobic form, where enzymatic cleaning and magnetically induced membrane vibrations should alleviate the fouling problem, but also anaerobic MBRs are gaining attention, best coupled to advanced membrane gas separations (to purifiy the produced biogas) and nanofiltration (to recycle the nutrients). In addition, membrane-based algae harvesting (to produce biofuels in a more energy-efficient way), reverse osmosis (to remove micropollutants from drinking water), forward osmosis (a relatively new energy-neutral membrane separation process) and pressure retarded osmosis (a membrane process even merely aimed at producing electricity!) will receive attention.

V-gas, a new source of drinking water – Rob Schotsman

Due to climate change and urban development the pressure on the available sources of drinking water is becoming more and more eminent. The search for reliable sources is on going. Even less favourable sources are considered like seawater and in arid areas even the effluent of waste water treatment plants. Also brackish groundwater is considered. One of the issues for treating brackish groundwater is the energy consumption, which makes it less attractive. On the other hand brackish groundwater is widely available, has most of the time a very good quality and does not contain any contaminants. When considering that very often brackish groundwater contains methane, this methane could help reducing the energy consumption. A technique to recover this methane is available.

In the Netherlands drinking water company Vitens started a project together with Haskoning to recovery methane from fresh groundwater by means of vacuum deaeration. The concentrations are so high, that the methane can be used economically for energy production. It is sufficient to reduce the overall energy consumption of the treatment plant by 40% or to let 300 – 400 company cars drive 30.000 km every year for free.

If this technique is applied in a wider range eq brackish groundwater, the production of drinking water based on brackish groundwater could become economically sound and energetic more attractive.

Supporting technologies: new business challenges – Willy Gils

Integrated new energy solutions and strategies enable full scale application of zero power consumption and/or zero discharge sewage treatment plants.

Power consumption optimization is a critical challenge when designing wastewater treatment plants. Waterleau developed the INESS^® (Integrated New Energy Solutions and Services) system for large sewage treatment plants (STP) aiming to decrease operational expenditures and to increase sustainability. As a first energy recovery strategy, the organic fraction of the municipal solid waste (OFMSW) will be co-digested together with the excess sludge from within the plant, increasing the biogas production. Cogeneration units will convert the biogas into heat and electrical power. Secondly, the covered LUCAS^® STP system allows the installation of photovoltaic panels capturing solar energy. Finally the third strategy consists of harvesting wind energy. The result is a power neutral or self-sustained STP.

Water re-use is another critical challenge. Membrane technologies such as membrane bioreactors (MBRs), and tertiary effluent filtration using ultrafiltration (UF) membranes, have gained increased user acceptance, and are now considered mature technologies allowing capacity increase with superior effluent and re-use. Waterleau designs, installs and operates such plants for both industrial and municipal applications. The result is a zero discharge treatment plant.

Examples of both challenges will be presented.

Future challenges in the Water Life Cycle – Peter Cauwenberg

Water has been considered in the past as a cheap and almost unlimited resource. The frequency of issues with water shortage, poor water quality or floodings increased over the last decades worldwide increased. A new concept for water life cycle needs to be developed supported by

1. an increased awareness of the intrinsic cost of water by consumers,


2. the introduction of clever water saving options en equipment,


3. the introduction of simple but effective measures like greenroofs,


4. a further closure of water loops and


5. technological innovations (e.g. membrane distillation, membrane technology,..)