The phrase reduce, reuse, recycle is purposely listed in order of sustainability. It is always better to reduce our consumption, then reuse products, and only then to recycle as much as we can.
Living with the earth instead of just on it has some unexpected benefits – such as the delight we felt when we sold our lawn mower. Before we built here, the land was maintenance-free woodland. After we built, it was still maintenance-free woodland because of our green roof.
Human waste is a delicate topic, whether you call it ordure, night soil, jakes, dung or guano. When we were nomadic or lived in small, scattered communities, managing our waste was no big deal. But it became a more repulsive problem when it was removed from our backyards and concentrated in rivers and highway ditches as populations converged in cities during the Middle Ages. When Londoners commonly held cut oranges to their noses against the stench of the Thames, enough was enough. The elimination of human sewage in congested residential centres became one of humankind’s biggest engineering agendas, and many parts of the world are still without any sewage systems.
If you live in a city with a municipal sewer system, you are pretty much limited to hooking up and using it because most cities frown on do-it-yourself sewage treatment. Unfortunately, municipal systems are incredibly expensive to build, use vast amounts of water, break down in heavy rains and are unsustainable in their present forms. For your cottage, though, or if you live in a more rural area, there are many choices including a privy, a composting toilet, a traditional septic tank, a peat moss tank or a biofilter.
The privy is just a hole dug in the ground to hold biological waste, whether you call it an outhouse, backhouse, thunderbox, biffy, dunny, long-drop or kybo. If sufficient moisture is available, natural bacteria within the waste materials, earthworms, amoebas, moulds and flying insects slowly decompose the wastes and form a compost pile in the pit.
This decomposition is slow but generally effective if the new wastes do not exceed the decomposition rate of the old ones. Where the percolation rate of water through the soil is slow and where there is not a large amount of waste entering the pit, the wastes can slowly decompose and be rendered harmless without causing groundwater contamination.
In sandy soils with a fast rate of percolation, or where the base of the pit penetrates topsoils and goes directly down to underlying gravel and fractured substone, waste liquids entering the unlined pit may quickly seep deep underground before bacteria and other organisms can remove contaminants, leading to groundwater pollution. This pollution can be slowed or prevented in newly dug privies by lining the base of the pit and the walls with a thick mat of grass clippings or other absorptive material. This material then decomposes and becomes part of the compost pile lining the pit that continues to act as a moisture sponge.
A composting toilet is a well-controlled version of a privy. Models range from simple twin chamber designs to very high-tech advanced systems with rotating tines, temperature and moisture probes, and electronic control systems.
They are effective biological converters of human and household “waste,” saving money and energy for you and your community. They initiate the regeneration of the Earth’s environment that is long overdue.
The benefits of composting toilets are many:
- Reduce water use by 20 per cent to 50 per cent;
- Lower water and sewer costs;
- Reuse the small amount of end product;
- Reduce the load on municipal sewage systems;
- Eliminate sewer back-ups;
- Reduce nutrient load on nearby watercourses;
- Can be used in difficult sites: rocky, high water table, no water storage, environmentally sensitive, close to running watercourses, and swampy ground.
Plus there is no odour. This is a decentralized method of sewage management to seriously consider.
In North America, approximately 25 per cent of the population relies on septic tanks; this can include suburbs and small towns as well as rural areas. In Europe, they are generally limited to rural areas only.
The term “septic” refers to the anaerobic bacterial environment. Wastewater enters the first chamber of the tank; solids settle and scum floats. The settled solids are anaerobically digested by bacteria and reduced in volume. The liquid flows through the dividing wall into the second chamber for further settlement and then drains in a relatively clear condition into a drain field.
Pumping the tank every four to five years is required to remove the irreducible solids that settle and gradually fill the tank.
Septic systems have problems:
- Excessive dumping of cooking oils and grease can cause the inlet drains to block;
- Flushing non-biodegradable hygiene products such as sanitary napkins and cotton balls will rapidly fill or clog a septic tank. These materials
- should not be disposed of in a septic system;
- The use of garbage disposals for waste food can cause a rapid overload of the system and early failure;
- Pesticides, herbicides, bleach, paint or solvents will damage the working of a septic tank;
- Excessive water entering the system will overload it and cause it to fail;
- Biofilms develop on the pipes of the drainage field and can lead to blockage;
- Septic tanks are ineffective at removing nitrogen compounds that can potentially cause algal blooms in receiving waters.
There are also environmental issues with septic systems:
- Byproducts include carbon dioxide, methane (a greenhouse gas 20 times worse than CO2) and hydrogen sulfide – a pungent and toxic gas;
- The discharge from a septic tank into the environment can trigger prolific plant growth including blooms of algae and potentially toxic cyanobacteria;
- Sandy or coarse soils adjoining water can become saturated with phosphate, posing a threat of oxygen depletion to nearby surface waters;
- In areas with high population density and septic systems, groundwater pollution often exceeds acceptable limits;
- Trees in the vicinity of a concrete septic tank have the potential to penetrate the tank as the system ages and the concrete begins to develop cracks and small leaks. Tree roots can cause serious flow problems due to plugging and blockage of drainpipes, but the trees themselves tend to grow extremely vigorously due to the continuous influx of nutrients into the septic system.
There are ways to handle your waste responsibly. Installing a composting toilet is one. Next time we will talk about two more sustainable methods: peat moss systems and the one we installed for our earth-sheltered house on the river: a biofilter.