2.5 Conventional Approaches for Wastewater Management
51
Fig. 2.12 Schematic diagram of a typical municipal wastewater treatment process [44]
aeration tank to oxidize the dissolved organics and biological impurities to CO 2
and hence greatly reduce the COD value of the water. The microorganisms then
flow into a secondary clarifier where the biomass settles out and removed as
secondary sludge (SS).
– Advanced or tertiary treatment: nutrients such as phosphorus and nitrogen, and
chemical contaminants remained after the secondary treatment will be removed
at this level using a number of processes including polishing ponds, ammonia
stripping or air stripping, biological nutrient removal (nitrogen and phosphorus),
biological ammonia removal, chemical precipitation (phosphorus), and filtration.
2.5.2 Treatment of Industrial Wastewater
Industrial wastewater is generated from various industrial processes such as manufacturing, mining and power generation. Thermal-electric power generation is responsible for the largest portion of wastewater discharge as it uses large amounts of
water for cooling and condensing the steam. According to Statistic Canada, industrial
wastewater discharges were 29.9 billion tonnes in 2009 [4]. In Ontario, all discharges
of wastewater to the environment are regulated under the Ontario Water Resources
Act. The industrial facilities that discharge wastewater directly into Ontario’s lakes
and rivers are responsible to sample their effluent, analyze it and report the results
to the Ministry of Environment of Ontario [45]. In fact, industrial wastewater can be
treated and the treated effluent is reused in the process, released to the sanitary sewer
or safely discharged to the environment. Treatments of industrial wastewater can be
divided into the following levels [46]:
51
Fig. 2.12 Schematic diagram of a typical municipal wastewater treatment process [44]
aeration tank to oxidize the dissolved organics and biological impurities to CO 2
and hence greatly reduce the COD value of the water. The microorganisms then
flow into a secondary clarifier where the biomass settles out and removed as
secondary sludge (SS).
– Advanced or tertiary treatment: nutrients such as phosphorus and nitrogen, and
chemical contaminants remained after the secondary treatment will be removed
at this level using a number of processes including polishing ponds, ammonia
stripping or air stripping, biological nutrient removal (nitrogen and phosphorus),
biological ammonia removal, chemical precipitation (phosphorus), and filtration.
2.5.2 Treatment of Industrial Wastewater
Industrial wastewater is generated from various industrial processes such as manufacturing, mining and power generation. Thermal-electric power generation is responsible for the largest portion of wastewater discharge as it uses large amounts of
water for cooling and condensing the steam. According to Statistic Canada, industrial
wastewater discharges were 29.9 billion tonnes in 2009 [4]. In Ontario, all discharges
of wastewater to the environment are regulated under the Ontario Water Resources
Act. The industrial facilities that discharge wastewater directly into Ontario’s lakes
and rivers are responsible to sample their effluent, analyze it and report the results
to the Ministry of Environment of Ontario [45]. In fact, industrial wastewater can be
treated and the treated effluent is reused in the process, released to the sanitary sewer
or safely discharged to the environment. Treatments of industrial wastewater can be
divided into the following levels [46]: