What is Better For the Environment?: Composting Food Waste or Sending it down your Garbage Disposal
Many people opt to send their food waste down the sink as a way of diverting it from the landfill, however this solution is not as environmentally friendly as it may appear.
Once sent down the drain, food is carried to a wastewater treatment plant before being released into nearby waterways (for Chicago, the Chicago River). Food increases the amount of nutrients such as phosphorus and nitrogen in wastewater. These are pollutants that need to be removed because they cause eutrophication, a process under which the excess of nutrients allows more algae and plankton to grow. This excess of algae and plankton use up a lot of oxygen, creating low oxygen levels in the river overall and cause fish to die-off. Food in wastewater creates an excess of nutrients that can disrupt the entire downstream river ecosystem.
Due to federal regulations from the Clean Water Act, all treatment plants in Chicago are required to meet pollutant thresholds to ensure decent water quality before it enters the river. Thus, food must be removed from wastewater in order to minimize pollution as much as possible. This process involves taking the food out and using it to make ‘biosolids,’ a wastewater treatment plant byproduct of the sewage ‘sludge’ that is nutrient-rich and can be used to make fertilizer. Biosolids are not compost by themselves, but they can be mixed with other organic material which lowers their overall pathogen count and creates a more compost-like substance. While the food still eventually ends up reused, wastewater treatment plants are incredibly energy intensive, with the national average consuming 30 terawatt-hours per year of electricity, or $2 billion in electricity costs.
Additionally, the treatment plants are not always able to get everything. Although much healthier now than it has ever been in the past, the Chicago River still remains susceptible to runoff pollution. Due to the fact that Chicago has a combined sewer system, major storms can cause sewers to overflow, which allows untreated wastewater (including food from the sink) to enter the river, creating nutrient pollution. That’s why on days with high precipitation, it’s important to conserve water to minimize the overall amount of water in the system. Besides sewer overflow, the river can be impacted by up to 1.2 billion gallons of undisinfected sewage effluent and nutrients daily. It’s most helpful to remove contaminants such as food at the very beginning to reduce the risk of water pollution.
Your sink garbage disposal has high energy costs, is not completely effective, and places a strain on both local water quality and wastewater infrastructure. The best thing to do for the environment is to compost with a service like WasteNot, where your food is diverted from a landfill.
