Grey Water System
From Swikipedia
Introduction
All the wastewater except for toilet wastes and food wastes which is derived from the garbage grinders is known as Greywater. 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.
Brief Description
Difference between Greywater and Blackwater:
1. Amount of Nitrogen: Greywater contains far less nitrogen than blackwater. Nine-tenths of the nitrogen contained in combined wastewater derives 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.
2. Amount of pathogens: 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.
3. Rate of Decomposition: 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.
Separation of greywater from blackwater is economical by installing dual plumbing lines at the time of construction.
Greywater Recycling:
The Greywater system consists of a stretch filter and a Soil-box planter. The aim of this stretch filter treatment technique is simply the removal of large particles and fibers to protect the subsequent infiltration pipes from clogging and transferring it as soon as possible for treatment into a biologically active, aerobic soil-zone environment where both macro- and micro-organisms can thrive. Stretch-filters are made to retain fibers and large particles and allow the rest of the organic material to travel on to the next stage of processing. This filter is suitable for public facilities where the principal source of greywater is hand-washing and showers without any food waste to speak of.
The soil-box planter contains a layer of polyethylene "actifill" or pea gravel at the bottom to provide effective drainage. This prevents the formation of water-logged zone in any part of the planter bed. A layer of plastic mosquito-netting on top of the actifill prevents the next layer of coarse sand from falling through. On top of the coarse sand is a layer of ordinary concrete-mix sand, while the top two feet consist of humus-rich top soil. Clay soils must not be used.
The pressure infiltration pipes are designed to allow for even distribution of the water even on uneven terrain. They are easy to clean and should be placed on the soil surface after planting and then covered with a 2 to 4-inch-thick layer of wood chip mulch.
Benefits of Greywater Recycling:
The potential ecological benefits of greywater recycling include:
• Lower fresh water extraction from rivers and aquifers
• Less impact from septic tank and treatment plant infrastructure
• Topsoil nutrification
• Reduced energy use and chemical pollution from treatment
• Groundwater recharge
• Plant growth
• Reclamation of otherwise misdirected nutrients
• Greater quality of surface and ground water when preserved by the natural purification in the top layers of soil than generated water treatment processes
References:
The Energy and Resources Institute. Sustainable Building Design Manual, Volume 2. p.p 43
