By Jan Weijma, LeAF
The purpose of sewers is to dispose of wastewater in a safe way. The purpose of sewage treatment plants is to ensure that it can be discharged safely and without damage to the environment. So, to summarize, current wastewater practices ensure that we and the environment are not becoming ill of our own wastewater.
The standard flush toilet, gravity sewer and sewage treatment plants, have fulfilled their function for decades. If you think about it longer, it becomes clear that the wastewater, for example from homes and offices have a totally different composition. Yet sewers can transport wastewater from both offices and homes and the mixed waste water can be treated at the WWTP. A football stadium mainly produces urine, also this can be discharged to the sewer. Thus, a robust and proven system. Nothing to worry about. And besides, change is quite difficult, right?
Nothing could be changed really, simply because there was no alternative to sewers and sewage treatment plants. You could say that sewers had an absolute monopoly on waste water transport and sewage treatment plants in wastewater treatment. The known means of transportation and processing was therefore never challenged, we never had to make a decision, and there was no comparison because there was no choice. Except perhaps for the rural areas, whether there had to be on-site treatment if pumped sewerage was considered too expensive.
Yet in the year 2016 there are developments that make some people got an uneasy feeling about the monopoly of sewer and wastewater treatment plant. A few of them I want to mention.
1. Infrastructural bottlenecks in construction and replacement of sewer
2. Obstructed flow in sewers
3. Scarcity of energy and nutrients
4. Costs, water management agreement
5. Alternatives exist nowadays
The question I often hear is whether the alternatives are ‘better’ than sewers and sewage treatment plant. This assumes that it is a choice between one or the other. We are so used to having one standard way of dealing with wastewater that we can hardly imagine that there are hybrid forms of conventional and innovative. Second, it shows that most of us do not realize that there are many types of wastewater flowing through our sewers. The question which is much more relevant and pragmatic, is whether the present system with gravity sewer and WWTP, is always better than other ways. Is it smart to discharge urine into the sewer in places where much urine is released, while we now know that phosphate ore is finite? Is it expedient to equip a vast industrial site with an equally vast gravity sewer where hardly water will flow through? Is it careful to discharge hospital wastewater into the sewer while we know that it contains nasty pathogens and drug residues, which are not all removed at the WWTP? Are the current efforts in the wastewater management in the countryside justified if it appears that they have little impact on the nutrient balance in the local water cycle? Would you deny citizens the opportunity to close cycles by recovering resources from wastewater ?
It is time to seize the opportunities of alternative wastewater practices with both hands. Rather than not ill, we then can become better from our wastewater.