Wastewater; a byproduct of drains and toilets from schools, homes, businesses and factories flow into sewer systems, on a daily non-stop basis. Other major producers of wastewater are rainwater, melting snow, water from street and sidewalk cleaning, as well as other runoffs flow through combined sewer systems destined for the city’s wastewater treatment plants.
Runoff water from operational and closed landfills is another source of wastewater. The amount of leachate produced by landfills varies with weather conditions. Dry days produce the smallest flow rate. Rainy days produce the highest amounts of runoff when rainwater combines with leachate. Dissolved organic matter, inorganic macro compounds, heavy metals and xenobiotic compounds are the four main groups of contaminates generally found in leachate runoff. These toxic compounds are generally collected at the site in tanks for treatment.