Greywater Treatment What is greywater Not blackwater Kitchen

Greywater Treatment

What is greywater? • Not blackwater • Kitchen water is sometimes treated with blackwater due to its high solids content

What about black water? • Don’t make it black in the first place and save yourself the trouble of dealing with it. • And if you do, don’t mix it with the grey water, at least until after its treated.

What is in greywater that needs to be treated? • Mainly we are dealing with: fats, oils, detergents, soaps, food, hair. • Potentially may contain contaminants such as bacteria, protozoa, fungi and parasites. • In general it is pretty clean though, as long as you don’t store it.

What sort of volumes are we dealing with? • Varies hugely • From 220 litres person per day - Luxury homes with insinkerators, high volume shower , bedays, etc • Down to 100 litres for households with compost toilets or re-used flush water (numbers from A. R. C. ) • The average person is 180 L (nth shore)

Average Household Water Use

Some more numbers to get a feel for where that water comes from • A toilet flush is usually either 11 L/5. 5 L or 6 L/3 L • The average is 5 flushes person per day, - 11 L flush = 55 litres x 4 people = 220 L/day = 80300 L / year

Washing machines • Average use between 100 & 200 Litres per wash. Dishwasher • 40 L per load Bath • 150 – 200 L Shower 75 L for every 5 minutes

Remember that water from rinsing her nappies will contain fecal matter

What are the benefits of on-site greywater treatment?

What are the drawbacks?

What are the onsite treatment options? Septic tanks are most common.

Standard disposal field

Benefits and drawbacks of septic tanks Benefits Proven technology with a wide range of suppliers Low or no power consumption Inexpensive Three-yearly pump-outs only Drawbacks Council may be resistant, especially on smaller sections and the system relies upon the soil for completion of treatment • Require sufficient land area and larger setbacks from ground and surface water • Dependent on the (sustained) treatment capacity of the soil • Nutrient loss off property • •

Aerated septic tanks

Benefits and drawbacks of aerated septic tanks • • • Benefits Wide range of off-the-peg systems ‘All-in-one’ packaged plants Relatively economical to purchase When operating well can produce a high quality effluent which makes disposal easier. Well accepted by council Drawbacks Significant power consumption, expensive operation Can be noisy Maintenance can be costly (replacement pumps, etc) Cope poorly with fluctuations in input (whether up or down) so less well suited to holiday homes, etc

Vermicomposting

Benefits and drawbacks of vermicompost system • Benefits • Probably cope better than other systems with a garbage grinder and even some chemical use • Produce a reasonable quality effluent • Low (or no) power consumption • Can be quite compact units • Can be used with drip irrigation (some systems) • Drawbacks • Poor nutrient reduction (nitrogen/phosphorous) (may be OK or even a benefit if water is used appropriately in a low-sensitivity receiving environment) • Some councils accepting of well designed systems, others are less so.

Taking Multi tasking to the next level