This paper documents the energy intensity and environmental impacts from operation of water
and wastewater treatment systems through case studies in the United States. Life-cycle
energy and impact assessments were conducted for the Ann Arbor Water Treatment Plant
(WTP) and Ann Arbor Wastewater Treatment Plant (WWTP) in Michigan. The framework for
assessment was modified to assess the environmental burdens from Laguna WWTP in California
and Ypsilanti Community Utility Authority (YCUA) WWTP in Michigan.
From the comparative assessment of the three WWTPs, it is found that the life-cycle energy for
the YCUA WWTP is the highest - 21 GJ/MG; out of which, 46% is from electricity used for
operation, 44% from natural gas used for the sludge incinerator and 10% from production of
chemicals used for treatment. For the Ann Arbor WWTP, electricity utilized accounts for 50%,
natural gas used for 25%, energy for sludge-hauling for 16% and energy in the form of chemicals
used for 9% of the total life-cycle energy of 16 GJ/MG. The life-cycle energy for the Laguna
WWTP is the lowest - 11 GJ/MG, as it meets the total requirement for natural gas and 40% of the
electricity required from methane produced upon anaerobic sludge digestion. Hence, 91% of the
life-cycle energy for Laguna WWTP is from electricity, 8% from chemicals and a mere 1% from
sludge-disposal.
From the assessment of the Ann Arbor "water and wastewater" system, it is found that the Ann
Arbor "water and wastewater" treatment system accounts for 54% of the total electricity required
by the Ann Arbor municipal government sector. Further, the life-cycle energy required for the
system is 40 GJ/MG of clean water, out of which 60% is from the operation of the Ann Arbor
WTP. The system also generates 5,230 kg CO<sub>2</sub> eq. /MG clean water or 3.57 million kg CO<sub>2</sub>
equivalent per year. Electricity required for operation of the Ann Arbor WTP and WWTP
contributes significantly to the total life-cycle energy and emissions. Thus, energy conservation at
the plants, adoption of renewable energy and an anaerobic sludge digestion system coupled with
co-generation unit would prove to be useful for reducing the total life-cycle energy and
environmental burdens from the system. Includes 12 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.2 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 59 |
| Published : | 11/01/2008 |
