Flushing away is not sustainable

By Johannes Wessels Time of article published Dec 5, 2012

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Every day the world population excretes more than 3 million kg of solid waste and passes 11.5 billion litres of urine: over a year the equivalent of a sizeable hill and a large lake.

The urine alone would, over a year, fill 80 percent of South Africa’s largest reservoir, the Gariep Dam.

What would be an appropriate manner to deal with this?

Sanitation can be defined as the measures, methods and activities for the safe collection, removal and disposal of human excreta, refuse and waste water.

In societies experiencing rapid urbanisation, many people live in squalor in dense, informal settlements. Much of the pollution that leads to high rates of disease, malnutrition and death, is caused by a lack of toilets and inadequate sanitation services.

In developed countries, people instinctively flush away their waste. Almost no one contemplates whether it is a good disposal method. In 2000, an internet survey in 17 countries listed the flush toilet as one of the top 10 inventions of all time, on the list with the internet, the cellphone, the car, TV and modern medicine.

This flush and discharge method can be on-site (septic tanks) or through a network of sewer lines, bulk water supply and sewer treatment works. The latter is an expensive system requiring a high commitment of resources for the installation and the maintenance and operation of that infrastructure.

In South Africa, the systems are in disarray and this year’s Green Drop Progress Report states that 69 percent of sewage treatment works present a critical or high risk (higher than 70 percent) with a mere 7 percent of plants having a risk below 50 percent.

The most dominant sanitation system worldwide is the pit toilet.

This drop-and-store method has severe disadvantages: odour, fly breeding, risk of spillage during heavy rains, permanent groundwater contamination – all contributing to major health hazards.

In a year the average person produces about 600 litres of urine and 140kg faeces. In water-borne sewerage systems, these are flushed away with 15 000 litres of pure water.

The bath, kitchen and laundry grey water add a further 24 000 litres per person a year.

On an assumption that 30 percent of the world population uses flush toilets, the urine, faeces and the water to flush, together with the grey water, would annually fill three times the 10 largest dams in South Africa, as well as the Katse and Mohale Dams in Lesotho.

At the end of the system there is supposedly a treatment plant, but in many cases the sewage is discharged completely untreated, or only semi-treated.

Water is often released from the treatment works without its quality meeting safety standards.

Because of the cost of flush systems, the Ventilated Pit Latrine (VIP) is considered an alternative.

Soil conditions are often not suitable to allow proper soak-away of liquids and VIPs become improper conservancy tanks.

Where there is a concentration of pit-latrines, the coliforms contaminate the groundwater, rendering it unfit for human consumption, as is the case in Thaba Nchu and parts of Lesotho.

Fresh faeces have four main groups of organisms: bacteria, viruses, protozoa and helminths.

In the network flush system, all these contaminate the water used to flush it to the treatment works.

On average the survival rate for bacteria in treatment ponds is 20 days.

Due to the chemicals added, the treatment ponds are, from a health point of view, more effective than septic tanks, VIPs and cesspits, where bacteria can survive for up to 400 days, and helminths for months beyond that.

To think that the crisis of waterborne diseases is restricted to the developing world is a mistake. It can occur anywhere because of poor maintenance, negligence and overloading.

Cholera is a rapid remover of life. People, fit for work in the morning, often are dead, dehydrated, contorted figures by the evening.

There is, however, a tested and tried alternative: eco-sanitation.

Several eco-sanitation methods exist (e.g. biogas plants or composting sanitation).

Eco-sanitation is relatively unknown in South Africa, but offers two broad and safe options: diversion or separation, where the urine is separated or diverted away from the faeces and never mix, or a mix-and-evaporate system.

The US National Sanitation Foundation found that composting toilets disposed of all four pathogens within seven days, compared with an average survival rate of 20 days in sewage treatment ponds and between 175 days to 400 days in a pit latrine that is no longer being used.

In addition, the coliform count in composting toilets was 25 times lower than the required norm.

The National Sanitation Foundation of the US has endorsed the Biolet. Health authorities in all Scandinavian countries, the UK, Germany, the USA, Switzerland, Australia and Japan, have given composting toilets the green light.

Electrolux, a giant in electrical white goods, distributes composting toilets (made by an independent manufacturer) in their dedicated white goods shops in Scandinavia.

Free standing, non-network, composting toilets are, from a cost perspective, a cheaper alternative than installing a waterborne sewerage system with treatment works.

We need to think of human excretions not as waste, but as a resource.

In Sweden, the concept of a composting toilet was developed in the late 60s to mid 70s because of major groundwater pollution of lakes and coastal areas.

Composting toilets are value-adders, not waste conveyors: they save water, cut operating costs and add compost. And they work: it is our heads that should be turned.

People will have to be educated on the correct usage of these toilets, but since it is on-site disposal, the bad impact of misuse will bring home the lessons on the correct usage far quicker than the misuse of a flush and discharge system.

With millions of people in southern Africa using unimproved pit latrines or no latrine at all, eco-sanitation is a serious alternative to expanding existing sewage networks.

There is a lot to be gained by transforming waste into a resource.

It would free several hundred million rand annually that would be required for installation and maintenance of sewer networks and running additional treatment plant capacity and increasing reservoirs.

And it will gradually remove one local authority function from the realm of public incompetence to the realm of individual responsibility.

* Johannes Wessels is from Rural Urban Integration Consultants

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