Household Dangers for Sewage Systems

It is estimated that between 1% and 5%, of domestic waste can be classed as 'hazardous waste' which could, unless dealt with appropriately, cause problems in the water environment.

Phosphate based detergents in particular are banned in some countries because they add nutrients to the waste stream which can cause eutrophication (or algae growth) in receiving waters.

Chlorine products - bleaches - are another problematic waste stream. It has been said: 'Every time you use the Toilet Block you are putting bleach into the environment. It all adds to the chlorine load.' Most people probably live in the mistaken belief that such products could only have a beneficial effect on the drains, because they kill germs, but this is not the case. With so much organic material and ammonia in sewage, the chlorine products react with these rather than bacteria, which is why chlorine is never added in the early stages of sewage treatment.

The problem is that these chlorine based products react with organic chemicals to produce chlorinated organic's - the same group of chemicals as the weedkiller DDT, PCB's and pesticides. They are not biodegradable, they persist in the environment and have a cumulative effect. They are not removed in the sewage treatment process. Many Experts predict there will be a general presumption against the use of chlorine products in future, apart from as a residual biocide in the water supply.

People also have a tendency to pour oils down drains the motor and kitchen varieties. Neither is particularly good for sewage treatment works processes and they sometimes cause problems in the sewers or drains, cooling down to become solid, blocking pipes and creating unpleasant odours.

Garden chemicals are another favourite candidate for tipping down the drain. The quantities may be small but the number of people doing this means that there are potentially large amounts entering the drains. These, in any quantity, could significantly affect biological sewage treatment processes by killing off the bacteria on which these systems rely.

Another great bugbear for the drains is sanitary products. These not only contribute significantly to the gross solids entering the sewage system but the plastics used in these items, can when burned, can give rise to chlorinated organic's in the combustion gases. Sanitary detritus statistics illustrate the size of the problem - every day, 2.5 million tampons are flushed, along with 1.4 million sanitary towels and 700,000 panty liners.

When disposed of down the drains - along with the ubiquitous cotton buds and baby wipes, cause untold problems. They block pipes and treatment works systems, reduce efficiency in sewage treatment processes and, if released through sewer overflows, remain in the environment to trap and choke wildlife and create a generally unappealing scene.

The disposal of unwanted medicines and pharmaceuticals programme, which has worked well in the past and there have been a number of initiatives for specific waste streams, such as the 'Oil Care' campaign which has set up 1,700 oil banks in the UK to allow motorists to dispose of used oil safely. There has also been a 'Repaint' scheme to recycle partly-used paint cans to community groups, and the British Agrochemical Association has issued guidance for gardeners on use and disposal of chemicals.

The new EEC Waste Directive. - The range of products which would fall under the ambit of this directive is extensive -

  • mineral and synthetic oils and fats;
  • paints;
  • varnishes;
  • ink;
  • adhesives and resins;
  • solvents;
  • low-pH acids;
  • high-pH alkalis;
  • photochemical's;
  • medicines;
  • pesticides;
  • lead and nickel-cadmium batteries and mercury dry cells;
  • mercury-containing waste, including fluorescent tubes;
  • aerosols;
  • equipment containing CFCS;
  • printed circuit boards and electronic equipment containing internal batteries;
  • hydrogen peroxide and bleaches;
  • syringes and needles;
  • equipment containing PCBs and PCTS;
  • materials containing asbestos,

Remember - with a small sewage treatment system these pollution problems will be made much worse!

For further impartial advice on any problems associated with all types of sewage and effluent treatment contact Johnston Smith Consulting - The Independent Specialists.