However, in order to have consistency between units, well convert this to cost per kWh: To do your own analysis using your local information, download this sample cost and ROI calculation spreadsheet. Request Permissions, Journal (Water Pollution Control Federation), Access everything in the JPASS collection, Download up to 10 article PDFs to save and keep, Download up to 120 article PDFs to save and keep. Accelerated Upgrade to Anaerobic Digestion Facility Wins New Business for City of Cortland, Cost Assessment and Design Considerations for Microfiltration and Ultrafiltration Membrane System Retrofits, Anaerobic Digestion Equipment - Selection and Operation Best Practices, Meeting EPA Regulations: Power Plant Wastewater Heavy Metals Removal. This test case represents a pessimistic scenario of the estimated savings. Monday Friday | 6am 3pm, 2022 Heron Innovators, Inc. | All Rights Reserved. The total energy cost for heating the water going to the digester is given by the following equation: Note: The digester does produce heat from the biological processes, so the natural gas consumption will not really be that high. Despite the findings of this report, some plants have chosen to skip the step of dissolved air flotation thickening and take their sludge straight to the digester without an additional thickening step. Please contact WesTech to get a quotation on an appropriate DAF system for your needs. Even in the most pessimistic case, thickening with a DAF prior to feeding the digester will result in substantial energy savings and cost savings. Typically natural gas is sold by $/MMBTU (dollars per million BTUs), the range for this unit of measure is $1/MMBTU to $6/MMBTU with an average of about $3/MMBTU.

A 2017 survey of commercial energy costs in the USA had a low of $0.075/kWh and a high of $0.29/kWh, with most utilities charging close to $0.10/kWh. For terms and use, please refer to our Terms and Conditions Solids recoveries averaged 83-99 percent. Heat is required in order to get from the wastewater temperature to the digester temperature. We have knowledgeable sales engineers ready to answer your project inquiries. For mesophilic digestion the target temperature is between 68F and 108F, with 98F being the most typical target. From 1973 to 1976, the EPA and the state of California sponsored a pilot study in Carson, California. Select the purchase All rights reserved. Well assume that the wastewater treatment plant produces 1000 gpm of waste activated sludge (WAS) in their secondary clarifier or clarifiers. Waste activated sludge goes from the secondary clarifier to the digester at a flow rate of 1000 gpm with a TSS concentration of 5000 mg/L. Generally, the temperature of the wastewater in any plant is dominated by the underground temperature in the region, which remains generally constant year-round for deeply buried pipes. Our online platform, Wiley Online Library ( is one of the worlds most extensive multidisciplinary collections of online resources, covering life, health, social and physical sciences, and humanities. The subsequent analysis compares the energy consumption of the thickening and digestion process with and without the addition of dissolved air flotation thickening. Email:[emailprotected], Business Hours The final technical report was completed in 1980 and is available on the EPAs website, entitled Waste Activated Sludge Processing (PDF), document EPA-600/2-80-147. Without a DAF (or other sludge thickening). However, the amount of energy released will be the same for both the thickened and not thickened case, so the relative cost difference will be the same. Headquarters3665 S. West TempleSalt Lake City, UT 84115U.S.A. Wiley has published the works of more than 450 Nobel laureates in all categories: Literature, Economics, Physiology or Medicine, Physics, Chemistry, and Peace. Other factors may influence this water temperature, but once the water makes it underground, the temperature of the underground pipes will determine the temperature of the water. Therefore the typical range of influent temperatures to wastewater treatment plants in the USA is: Most of the country falls in the 50F-60F range. |. This item is part of a JSTOR Collection.

Here well assume the average temperature, natural gas, and electrical costs. Heating the thickened sludge will use substantially less energy than heating the unthickened WAS. However, aerobic digestion did not have a significant benefit and, due to the additional energy input required, was discarded in favor of anaerobic digestion, which also produces a usable source of energy. Wiley has partnerships with many of the worlds leading societies and publishes over 1,500 peer-reviewed journals and 1,500+ new books annually in print and online, as well as databases, major reference works and laboratory protocols in STMS subjects. Wiley is a global provider of content and content-enabled workflow solutions in areas of scientific, technical, medical, and scholarly research; professional development; and education.

1967 Wiley Tel:916.408.6601Fax:916.408.6991 With a growing open access offering, Wiley is committed to the widest possible dissemination of and access to the content we publish and supports all sustainable models of access. Several technologies were tested for the handling of waste activated sludge, but the process endorsed by the report was that dissolved air flotation be adopted for thickening of waste activated sludge. Our core businesses produce scientific, technical, medical, and scholarly journals, reference works, books, database services, and advertising; professional books, subscription products, certification and training services and online applications; and education content and services including integrated online teaching and learning resources for undergraduate and graduate students and lifelong learners. The flow going to the digester is Q=1000*0.5%/4%=125 gpm. Read your article online and download the PDF from your email or your account. The amount of heating energy needed will be the critical component of the cost of using a digester without a DAF vs. using a DAF. Fortunately the specific heat of water doesnt change much with temperature and ranges between 4.178 kJ/kg/C and 4.205 kJ/kg/C under the conditions usually seen in wastewaters. Estimated total installed cost of DAF system: $600,000. Sludge thickening by dissolved-air flotation is accomplished by dissolving air in water at high pressure and then reducing the pressure, thus forming small air bubbles that attach themselves to sludge particles and float them to the surface. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of information and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. SAF may be used in place of a rotary drum or gravity belt thickener and offers many advantages, including greater percent solids and significantly less chemical demand. Access supplemental materials and multimedia. Addition of polyelectrolytes at several plants yielded thickened sludge concentrations of over 4 percent and solids recoveries of 99 percent. A 40' diameter DAF with a 1200 gpm recycle is used to thicken the sludge from 0.5% (5000 mg/L) to 4% (40,000 mg/L). Calculations assume moderate electrical costs, cheap natural gas, a high water temperature to start, and the same sludge as Test Case #1. Note that weve assumed 3.785 kg/gal to be the density of water. Get the info you need to more effectively design, manage, and maintain your operations. All content 2022 WesTech Engineering, LLC. For the purposes of this analysis, well use: In order to do a cost comparison, we will need to put a price on both electrical power as well as natural gas, because the efficiency of heating using electrical power is very bad. 10624 Industrial Avenue, Roseville, CA 95678 Both aerobic and anaerobic digestion were considered. Reduce Energy Costs Using Dissolved Air Flotation for Waste Activated Sludge Thickening. Heron Innovators The DAF system electrical loads are: Recycle Pump: 55 kW, Air Compressor: 5 kW, Drive Motor: 1 kW. option. Journal (Water Pollution Control Federation) Heron Innovators Suspended Air Flotation (SAF) process systems thicken two basic types of biological solids, aerobic and anaerobic.These solids are commonly referred to as waste activated sludge (WAS) and digested solids. Check out using a credit card or bank account with.

The analysis will compare using the following equations. Performance results obtained at plant-scale installations of various sizes show increases in sludge concentration, unaided by chemical addition, from 0.5-2.3 percent in feed sludge to 3.7-8.6 percent in thickened sludge. Cooling Tower Makeup Water and Sidestream Treatment, download this sample cost and ROI calculation spreadsheet, ROI based on a 20-year estimated life of DAF: $8.19 M, ROI based on a 20-year estimated life of DAF: $1.02 M.