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Wastewater Treatment and Reuse - Coggle Diagram
Wastewater Treatment and Reuse
wastewater constituents
blackwater (worst, most dangerous)
urine
brownwater -> toilet (feces, water) -> highest level of pathogens + heavy metals (arsenic, lead, mercury), wastewater also contains pharmaceuticals
components
toxic organic compounds --> from common products such as cosmetics, food packaging etc, chemotherapy drugs
pharmaceutical residue/hormone
heavy metals (arsenic, lead, iron)
nitrogen kg/person/year
organic matter kg/p/person/year
pathogens(bacteria, viruses, helminths)
water lit/person/day flush included
greywater
heavy greywater (have chemicals) -> dishwashers, kitchen tap, washing machine
detergents has organic matter (phosphorous, sodium salts, bleaches), soap contains alkali salts with long-chained fatty acids-> also organic matter
light greywater (slightly less chemicals) -> shower, bathroom tap
potential impact of wastewater
phosphorus + nitrogen -> eutrophication + consume oxygen
eutrophication
:excessive nutrient richment of water, leading to algae blooms and ecological imbalance
waste and fertiliser runoff and leaching --> nitrogen + phosphorus pollution in water -> abundance of nutrients causes algae bloom -> algae blocks sunlight -> plants die -> bacteria use up oxygen to break down decaying matter lack of oxygen suffocates fish
heavy metals -> toxic to humans
organic matter -> deplete oxygen + encourage bacteria growth
organic toxic compounds -> toxic to humans
pathogens -> infections
origins of pathogens in wastewater
greywater -> from laundry, washing diapers, food stuffs, etc
industry -> from abattoir and food industry (plant pathogens)
urine -> only a few diseases are transmitted through urine
storm water -> from surface run-off and animal faeces
faeces -> contain major amt of pathogens and intestinal infections
emerging pathogens
zoonoses -> from animals to humans
rotavirus -> most common cause of severe diarrhea among children
pharmaceuticals -> toxic to aquatic life
wastewater control
ways to minimise waste water
principles
pre-treatment: storage of urine/faeces, septic tank, grease filter, screen etc
treatment:
aerobic process: trickling filter, soil/sand filter, constructed wetland, ponds: facultative and maturation
anaerobic process: anaerobic baffled reactor, anaerobic ponds
source control: minimise water use, reduce contamination by chemicals, oil, particles, fats and excreta
wastewater treatment principles
chemical propeties
organics: TOC, protein and carbohydrate
Inorganics: Ammonium, phosphate, TN, ALK, and metals
biological properties
physical properties
others: temperature, pH, colour, absorbance, and odour
solute: ionic strength
solids: turbidity
physical characteristics of water:
solids
Total Dissolved Solids (TDS)
TSS
TDS is related to hardness and salinity
Volatile Solids (VS)
VS are burned off at 500 degrees, leaving fixed solids
temperature
optimum temperature for biological activities is 25-35 degrees celsius
too high a temperature results in cell death, lysis, denaturation, too low temperature will result in much reduced activities
colour
detected through the spectrometer
wastewater treatment processes
wastewater reuse
challenges and possibilities
environmental impact
causes surface water and groundwater pollution
aids mosquito breeding
causes health hazards as it contains pathogens and toxic compounds
generates unpleasant odours
benefits of treated wastewater
reduces water shortage
reduces environmental degradation, eutrophication and health hazards
reclaims otherwise wasted nutrients
protects the quality of groundwater and surface water