Living Machines - Comparison With Conventional Treatment

Comparison With Conventional Treatment

Björn Guterstam critiques conventional wastewater treatment for five different inadequacies that living machine systems address. This evaluation explains the basis of his five points of contention:

• First, conventional treatment focuses narrowly on treating water and produces an often toxic sludge as a by-product of this cleaning process. Living machine systems can greatly reduce this sludge by conversion into biomass.

• Conventional treatment uses environmentally harmful chemicals (namely chlorine) to disinfect effluent following precipitation of solids (sludge) from the wastewater stream. Ecological treatment uses biological processes instead of chemical inputs.

• Traditional processes do not adequately sequester heavy metals, and the sludge can also contain manmade organic compounds that are extremely difficult to break down. Some critics assert that the disposal of this sludge is not responsibly overseen in the United States, so the excess sludge is sometimes spread on public forest or even agricultural land, dumped in landfills or the ocean, and sometimes incinerated. This not only pollutes the environment with unnaturally high concentrations of toxins but also wastes a valuable resource. Living Machines can sequester heavy metals by plant uptake and the plants can be incinerated and the metals isolated in ash for safe storage. These life-giving machines convert sludge into organic tissues such as fish, flowers and medicinal plants that have human uses.

A contained microsystem can be very successful in recycling nutrients, organic matter, and water. Depending on the toxicity and makeup of the influent, living machines can treat water to tertiary treatment standards and even reach potable standards for most or all metrics. This excellent organic recycling is possible if the biosolids are not heavily contaminated with persistent pollutants (such as aluminum, which retards biotic growth). Mixed domestic/industrial municipal influent is more polluted, so a living machine may not always be able to treat every contaminant to levels that would not stress the ecosystem that receives the effluent. In this case, more treatment is necessary, which can be achieved by drainage into constructed wetlands which provide a different type of ecosystem that provides a fresh lineup of ecological players and services that can further process pollutants.

• Previous generations of Living Machine systems have employed clams to filter colloidal materials and fine suspended solids. Conventional treatment runs into engineering troubles when it attempts to handle these microscopic particles.

• Conventional treatment is capital and energy intensive, whereas natural treatment is design intensive (and also management intensive if it is not well designed). The embodied fossil fuel energy in the heavy industrial infrastructure used in traditional activated sludge treatment is much greater than in the construction of a living machine system with a large greenhouse, manufacture of plastic tanks, mechanical aerators, pumps and valves among other equipment.

Guterstam contends that traditional facilities require larger capital investment and demand more labor and energy costs than their ecological counterparts. It is difficult to make a generalization about economic comparisons because thus far living machine systems have only been built for single commercial buildings. The next step in the development of these systems would be a larger scale ecosystem that has more diversity and higher populations to treat a larger volume of sewage. Until there is an equivalence of scale, economic comparison between the two systems is somewhat awkward and speculative. However, it is safe to say that Living Machine systems are ecologically superior.

Conventional wastewater treatment is heavily embedded in our industrial toolkit. A worldwide revolution in wastewater treatment would require an entire industry and profession to make a major disciplinary shift from a focus on industrial engineering to ecological engineering, applied biology and ecology. Living Machine systems have yet to be made on a comparable scale to conventional treatment plants, and this “biology of scale” could bring benefits or drawbacks in efficiency.