Treating wastewater may be our last hope to save the planet
The UK Royal Commission was set up in 1898 to review methods of sewage treatment, it took 17 years and 10 reports to complete their findings. A final report was produced with regards to the effluent water quality standard to be discharged by municipal waste water treatment systems. The standard was set at 20mg/l BOD and 30mg/l suspended solids, as long as there was more than an 8 to 1 dilution of the waste water entering a river. Today, very few effluent treatment plants are actually in compliance with this standard set 120 years ago, also the chemical nature of the waste water has now changed and is thousands of times more toxic than is was 100 years ago.
Prior to the 1940's most of the wastewater entering the rivers and seas was organic in nature, it was basically human and animal waste. There were no antibiotics, pharmaceuticals, cosmetics, agrochemicals, POPs persistent organic pollutants. The wastewater would have a local impacts, but once diluted in the rivers and sea, it would act as a fertiliser to promote the growth of plankton and marine life. In essence there was absolutely no problem with the wastewater. However we are now dealing with thousands of very toxic chemicals that are not broken down over time in the environment or removed by municipal waste water treatment plants, yet we are still applying the same standards and water treatment process that were applied 100 years ago.
With regards to chemicals such as Oxybenzone, PCBs, fire retardants PBDE, organic tin and mercury to name but a few, these chemicals are not removed by wastewater treatment and they simply build up in the marine ecosystem. The deepest part of the oceans is the Marina Trench, it is over 10,000m deep and located 500 km South of Japan. The concentration of PCBs on the seabed in the trench are 50 times more toxic than the most polluted river in China. What ever is discharged into a river or through a municipal waste water treatment plant will eventually end up in the oceans and it will accumulate. The chemicals will build up in the sediment, in the bacteria, fish, whales, birds and then man.
The chemicals are toxic because they are bioactive, they will tend to get adsorbed on the micro-particles such as plastic and are then consumed by plankton or adsorbed directly into cells. The chemicals accumulate in the organisms, more than 1 and 15 of all life in the oceans, and by all life I also means bacteria, will contain micro-plastic. Many plastics will contain Oxybenzone as a UV light stabiliser, or organic Tin as a plasticiser or even toxic Triclosan used in soap to stop bacteria from growing. One particle of plastic can be sufficient to kill the organisms, especially if it has concentrated other toxic chemicals on its passage through the effluent treatment plants on its way to the Oceans. Given that 1 in 15 organism contain plastic, the ecological implications are profound. Plankton are the route of our food chain, they are the life support system for the planet, yet we have already killed 50% of the plankton and the remainder is being killed at a rate of 1% year on year. As we lose the plankton, the impact of of carbon dioxide become more serious and the oceans become more acidic.
In accordance with the IPCC the oceanic pH ( acidity) will drop to pH7.95 over the next 25 years, and as a marine biologists designing the life support system for many of the worlds largest public aquaria, we know for sure that there will be a trophic cascade collapse of the entire marine ecosystem at this pH. However we dont have 25 years to fix the problem, because of the inertia in the system, we need to eliminate all pollution from entering the oceans over the next 10 years. There is no safe level of these toxic chemicals, it has to be zero discharge for zero impact. In reality there will be no way we ca achieve this goal, however we can install tertiary treatment on the back end of municipal and industrial wastewater treatment plants. Currently, only about 5% of all systems have tertiary treatment. With the appropriate water filtration system to remove particles, especially micro-plastics down to 1 micron, then more than 90% of the toxic chemicals can be removed. The cost of such a system would be around 20usd for every person on the planet. So for a cost of 20 USD we can probably save the oceans, reverse climate change and save humanity.
Throw the planet a LifeLine, and install proper waste water treatment system, because in 10 years it will be too late.