Municipal Sludge disposal economics

Abstract

Costs for disposal of sludges from a municipal wastewater treatment plant normally represent at least 25 % of the total plant operating cost. The most popular ultimate disposal options and rough estimates of the extent of use are as follows:Percent of Amount (dry solids, sludge tons/day) Landfill 25-30 >4000Land application 25-30 >4000Incineration 25-30 >4000Ocean dumping 15 2500 Total >14 500 Sludge handling options considered are shown schematically in Figure 1. Option 1 includes two possible sludge dewatering processes prior to incineration: vacuum filtration to produce a 20% solids cake (Option 1a), or filter press dewatering to produce a 40% solids cake (Option 1b). Option 2 substitutes thermal conditioning of the sludge for the chemical conditioning of Option 1a.

Raw Water Processing and Wastewater Treatment

“…Frequently the costs of sludge treatment and ultimate disposal or destruction equal all the other costs of sewage treatment [47]. Frequently the costs of sludge treatment and ultimate disposal or destruction equal all the other costs of sewage treatment [47].…”

Atmospheric emissions of elements on particles from the Parkway sewage-sludge incinerator

“…Before sludge can be incinerated, the reactor bed is heated to 760 °C by burning No. 2 fuel oil, which is cut off when the temperature is achieved and the sludge flow is initiated.…”

“…Although sewage sludge contains enough nutrients to be used as low-grade fertilizer, the concentrations of toxic metals such as Pb and Cd are often so great as to raise serious questions about the use of this material on food crops, or in other ways in which the toxic metals may be released to the environment (7). Thus, many communities have built or are planning construction of sewage-sludge incinerators that will burn the sludge for two basic purposes: volume reduction and solids sterilization (2).…”