Top 10 Reasons to Focus on Gray Water Treatment
The limited water resources in the Kingdom, and the commitment to protect the environment, are among the most important reasons that motivate us to take the necessary measures to conserve water and use gray water treatment technology.
Gray water is the sewage discharged from homes including showers, washing machines, drains, and kitchens. except for the sewage of toilets (black water).
Top 10 Reasons Why We Should Focus On Gray Water Treatment
They can be listed as follows:
- Gray water treatment leads to water conservation.
- Gray water recycling and treatment is easy, simple, and low cost compared to black water treatment.
- Treated gray water does not carry any harmful bacteria or disease-causing pathogens.
- Gray water treatment reduces the amount of wastewater.
- The treated greywater provides a new, reliable supply of irrigation water in several places such as (university campuses, sports fields, gardens, golf, and Home gardens) which leads to increased agricultural productivity.
- Treated gray water is a new water source for firefighting systems.
- A new water source for industrial use.
- Treated gray water provides a new water source for concrete production
- Provides a new water source for car wash companies.
- Treated gray water can be used to flush toilets.
Reasons for using gray water treatment in agriculture
(In the past three decades, there has been a significant increase in the reuse of wastewater in agriculture as special events occurred in semi-arid areas and several factors led to this trend) World Health Organization 1989. Among these factors:
- The scarcity of alternative water sources for irrigation.
- The high cost of industrial fertilizers.
- Demonstrate that the risks and soil damage are minimal if precautions are taken.
- The high cost of advanced wastewater treatment plants.
- Social and cultural acceptance of the practice.
- Water resource planners recognize the value of the practice.
Factors affecting gray water quality
The composition of greywater depends on several factors, including the sources and installations in which the water is collected:
- Quality and type of water supply (groundwater well or piped water).
- Type of drinking water distribution network.
- The type of gray water distribution network (due to filtration from pipes, chemical, and biological processes in biofilms on the walls of the pipes).
- Activities at home (lifestyle, and use of chemical products).
- The installation through which gray water is drawn (kitchen sink, bathroom, hand basin, or washing machine).
- Source type: Domestic or industrial uses such as commercial laundries.
Geographical location. - Demographics and occupancy level.
- The amount of water used in relation to the amount of material discharged.
Summary of properties of untreated gray water from each source
Gray water collected from laundries
Microbiological properties: heat-resistant variable coli loads
Chemicals: Sodium, phosphate, boron, surfactants, ammonia, nitrogen from soaps, soiled clothes
Physical properties: high content of suspended solids, lint, and turbidity
Biological Traits: High Biochemical Oxygen Demand (BOD)
Gray bathroom water
Microbiological properties: Low levels of heat-resistant coliforms.
Chemical: Soap, shampoo, hair dye, toothpaste, and cleaning chemicals.
Physical properties: high content of suspended solids, hair, and turbidity.
Biological traits: Low levels of biochemical oxygen concentrations.
Gray water collected from kitchens
Microbiological properties: heat-resistant variable coli loads
Chemicals: detergents, cleaning agents
Physical properties: food particles, oils, fats, greases, turbidity
Biological traits: high demand for biochemical oxygen
The difference between the use of gray water and black water in irrigation
Regular use of products such as soap, shampoo, toothpaste, shaving cream, and food scraps. Cooking oils, dishwashing detergents, laundry detergents, and hair, and lint will also do no harm to growing soil and plants if gray water is used to irrigate gardens.
We should avoide products containing Boron as it is toxic to plants even in small amounts.
Washing wastewater contains high levels of sodium. The sodium in the washing wastewater may be due to the anti-sodium use of various anionic surfactants in the water used in powdered laundry detergents and the use of sodium chloride in ion exchangers.
Heavy metals in gray water
Both plastic and metal pipes release compounds, such as XOCs and heavy metals, into the water supply and greywater. Gray water contents depend on three sources:
- Chemical products resulting from the use of water
- Type of pipes used for transportation
- The quality of the water supply as it leaves the waterworks
Physical properties of gray water
Temperature
Gray water temperatures are often higher than the temperature of the source water. Because of the hot tap water used for personal hygiene and washing.
High temperatures encourage microbial growth and precipitate some substances such as calcite in supersaturated water.
Turbidity color and suspended solids content
Turbidity and suspended solids measurements give information about the content of particles and colloids that can clog the pores of soils and structures. The highest values are generally found in gray water generated in kitchens, sinks, and washing machines.
