It is no surprise to many, that using water to transport sewage into municipal treatment plants is not the most efficient or eco-friendly way of managing human waste. Few people, however, realize that there are several alternatives to traditional flush toilets. Incinerating toilets act as an alternative to flush toilets by heating, or “incinerating” sewage on-site at a person’s home or property.
How Do Incinerating Toilets Work?
The process waste goes through in an incinerating toilet is relatively simple. The user of the toilet places a small paper cone in the toilet; this cone is used so that no waste sticks to the toilet bowl, as flushing is not an option. After the user has finished, the paper (now filled with waste) is dropped into a chamber using a pedal or electric button.
Once in the chamber the paper and waste is moved into a burning chamber, which is activated by the user. Depending on the model, waste is incinerated for ten to twenty minutes, and reduced into an ash form.
Incinerating toilet systems use various fuel sources to incinerate the waste, but fuel sources are generally limited to propane, natural gas, or electricity. Many systems require both a small electric charge from a battery system, as well as a gas source for the incineration process.
UK has deemed this ash residue as germ free, and estimates that roughly one tablespoon of ash is produced per single use. Because 90-98% of all waste is moisture, the majority of the waste’s mass is evaporated into the air. Users must empty the waste chamber from time to time to maintain the efficiency of the incinerator.
Ash residue can be thrown into any regular trash bag for disposal. Because all nutrients have been burned away from the waste, it is of no benefit to use incinerator ash for garden applications.
Are Incinerating Toilets Green?
While incinerating toilets are thought to be “pollution-free” there are several environmental disadvantages to the incineration of human waste.
Primarily, incinerating toilets do not avoid the use of fossil fuels in the handling of waste. Whether electricity is coming indirectly from a coal-fired power plant, or directly from a tank of propane or natural gas, these fuel sources are all derived from fossil fuels. Alternative fuel sources such as wind, and solar systems can be used to power incinerating toilets, and thus reduce fossil fuel dependence.
Additionally, incinerating toilets fail to harness the nutrients of waste by destroying them in high heat, or releasing important molecular compounds into the atmosphere.
While incineration systems do provide some environmental disadvantages, comparing incinerating toilets to traditional wastewater treatment systems provides more insight into the “greeness” of incinerating toilet systems.
The basic process of wastewater treatment uses water as a carrier of waste. The average toilet uses one to three gallons of water per flush to thrust an individual’s waste into the municipal treatment system
In underground piping, wastewater is channeled toward the treatment facility where it is pressed, processed and released into a local body of water such as a stream, river, or ocean. Within the treatment process microbes are used, much like the composting toilet process, to degrade waste to a simpler form. Chemicals and minerals such as lime are often added, and the remaining liquid, or “effluent” is discharged into the local water body. The solids, known as “sludge”, are often shipped to landfills for burial.
Treatment facility discharges are sampled and monitored by local, state, and federal agencies in most developed countries, but certain unavoidable issues arise with this discharge. One environmental hazard to treatment plant discharge occurs when the effluent, which is often much warmer than the local water body, is released. The effluent creates a very low dissolved oxygen level in the area of the discharge. Low dissolved oxygen levels can be a threat to aquatic life as it creates a natural barrier for moving upstream.
UK Geological Survey also identifies other wastewater treatment hazards such as the introduction of untreatable pharmaceuticals to ecosystems; introduction of heavy metals such as lead, and cadmium; introduction of treatment chemicals such as chlorine; and, the introduction of nitrogen-based hazards caused by incomplete treatment.
When compared to traditional wastewater applications, incinerating toilets do indeed become a green alternative. Consumers looking for an even more environmentally friendly toilet system should consider composting toilet systems.