Cities Are Learning to Use Wastewater as a Valuable Resource
Wastewater is becoming an asset rather than a disposal problem as some cities’ recycling efforts become more sophisticated.
Wastewater treatment plants are increasingly recognized as community resources for electricity, fertilizer, and heat, as waste to energy projects become commonplace.
Wastewater is a continuous source of energy that will only increase over time.
One of the most valuable waste products is methane gas, which is one of the most effective and efficient ways for new or upgraded Wastewater Treatment plants to generate energy for their own operation and for surrounding communities.
According to the Water Environment Research Foundation, wastewater contains up to ten times the energy needed to treat it.
Wastewater Treatment plants are currently responsible for approximately 1.5-percent of total U.S. energy consumption. For some municipalities, this translates to 30 to 40-percent of the total electricity bill.
Nevertheless, some newer Wastewater treatment plants are becoming net energy positive, producing enough power through a combination of microbial activity, efficiency improvements, and mechanical modifications to offset the energy needed to operate.
WWTPs can be sources of hydropower, capturing and redistributing the energy produced as water circulates throughout a plant. Some cities currently use the heat in wastewater much like a geothermal heat pump, resulting in billions of bulk gallons that are cool in the summer and warm in the winter.
Fertilizer is another important product of wastewater treatment.
Science News reports:
[It is reported that] sewage treatment plants in the United States use about 1.5 percent of the nation’s electrical energy to treat 12.5 trillion gallons of wastewater a year. Instead of just processing and dumping this water, they suggest that in the future treatment facilities could convert its organic molecules into fuels, transforming their work from an energy drain to an energy source. Based on their research, they estimate that one gallon of wastewater contains enough energy to power a 100-watt light bulb for five minutes.