Greywater Recycling
This is a small excerpt from Carl Lindstrom's Website on Greywater. There is much more technical information on greywater recycling at his site.
Greywater is washwater. That is, all wastewater excepting toilet wastes and food wastes derived from garbage grinders. There are significant distinctions between greywater and toilet wastewater (called "blackwater").
These distinctions tell us how these wastewaters should be treated /managed and why, in the interests of public health and environmental protection, they should not be mixed together.
Fig 1. Greywater recycling soil box system example.
Greywater irrigation has long been practiced in areas where water is in short supply. However, proper precautions for its use have not always been observed. This has posed a problem for health officials, who contend that there is no good management method for greywater which both balances user needs with public safety considerations. In fact, options for making safe use of greywater as a source for irrigation are many and diverse.
The engineering of these systems is still a relatively young technology; but it is one making rapid progress. It also makes sense from both the environmental and "waste" management points of view.
As these systems utilize the nutrient (potential pollutant) content in the effluent, they constitute a real solution to the treatment /management of greywater. "Real solution" here means that these greywater recycling /management systems simply do not generate waste products which, by definition, require disposal.
Greywater and Blackwater: Key differences
Fig 2. Greywater / Blackwater in daily household wastewater.
Greywater contains far less nitrogen than blackwater
Nine-tenths of the nitrogen contained in combined wastewater deriveves from toilet wastes (i.e., from the blackwater). Nitrogen is one of the most serious and difficult-to-remove pollutants affecting our potential drinking water supply.
Greywater contains far fewer pathogens than blackwater
Medical and public health professionals view feces as the most significant source of human pathogens. Keeping toilet wastes out of the wastewater stream dramatically reduces the danger of spreading such organisms via water.
Greywater decomposes much faster than blackwater
The implication of the more rapid decomposition of greywater pollutants is the quicker stabilization and therefore enhanced prevention of water pollution.
See different treatments of greywater >>>
Greywater Recycling.
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