EN8591 – WASTE WATER ENGINEERING UNIT 2 – PRIMARY TREATMENT OF SEWAGE SESSION – 4 – GREY WATER HARVESTING MATHANAKEERTHI S / AP / CIVIL 2/13/2020 1 ENGINEERING / SNSCE Objectives of grey water harvesting • To reduce fresh water extraction from rivers and aquifers • To minimize the load on septic tank and treatment plant • To follow reuse and recycle procedure. • To increase the groundwater recharge. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 2 ENGINEERING / SNSCE GREY WATER • Grey water (also spelled gray water in the United States) or sullage is all the wastewater generated in households or office buildings from streams without fecal contamination, i.e. all streams except for the wastewater from toilets. • Sources of grey water include sinks, showers, baths, washing machines or dishwashers. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 3 ENGINEERING / SNSCE GREY WATER HARVESTING • The application of grey water reuse in urban water systems provides substantial benefits for both the water supply subsystem by reducing the demand for fresh clean water and for the wastewater subsystems by reducing the amount of wastewater required to be conveyed and treated. • • Treated grey water has many uses, for example, toilet flushing or irrigation etc. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 4 ENGINEERING / SNSCE • Grey water contains dirt, food, grease, etc. without pathogen loading. • Even though it is “dirty”, it is a safe and beneficial source of irrigation system. • Grey water will act as a valuable nutrients to plants. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 5 ENGINEERING / SNSCE Treatment processes • Requires separate treatment when compared with toilet waste water as this contains heavy pathogen load and makes the process very tough. • When grey water is mixed with toilet wastewater, it is called sewage or black water and should be treated in sewage treatment plants or an onsite sewage facility, which is often a septic system. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 6 ENGINEERING / SNSCE Treatment processes Preliminary treatment Screens and Grit chamber Primary treatment Sedimentation MATHANAKEERTHI S / AP / CIVIL 2/13/2020 7 ENGINEERING / SNSCE Applications of grey water harvesting • Toilet flushing • Washing machines • Plant watering systems Eg: sprinklers • Outside taps MATHANAKEERTHI S / AP / CIVIL 2/13/2020 8 ENGINEERING / SNSCE Types of Grey water reuse systems 1. Laundry to landscape system MATHANAKEERTHI S / AP / CIVIL 2/13/2020 9 ENGINEERING / SNSCE Then the grey water from the drum can be diverted into yard for irrigation 2. Laundry to drum system developed by Art ludwig MATHANAKEERTHI S / AP / CIVIL 2/13/2020 10 ENGINEERING / SNSCE 3. Gravity pump system from shower MATHANAKEERTHI S / AP / CIVIL 2/13/2020 11 ENGINEERING / SNSCE 4. MATHANAKEERTHIBranched S drain/ AP / CIVIL system 2/13/2020 12 ENGINEERING / SNSCE 4. Branched drain system • Grey water flows through standard 1 1/23 size drainage pipe by gravity. • Slope is 2% and drop of ¼ inch for every feet • Drop travel horizontally and the water is divided into smaller and smaller quantities using piping system that divides the flow to various parts. MATHANAKEERTHI S / AP / CIVIL 2/13/2020 13 ENGINEERING / SNSCE 5. Sink to flush system MATHANAKEERTHI S / AP / CIVIL 2/13/2020 14 ENGINEERING / SNSCE 6. Constructed wetland system MATHANAKEERTHI S / AP / CIVIL 2/13/2020 15 ENGINEERING / SNSCE 7. pumped system MATHANAKEERTHI S / AP / CIVIL 2/13/2020 16 ENGINEERING / SNSCE .