Waste Water Management
The comparison on wastewater management has several options that municipalities consider while engineers research the efficient use of either secondary treatment or tertiary treatment. The two has opened a debate by a city council member wanting to use secondary water treatment instead of tertiary treatment. To compare secondary water treatment and tertiary treatment the EPA has a report that represents 23 municipalities in the United States. Their observation includes the study of chemicals additives and filtration that have proven to lower levels of phosphorus.
The comparisons are outline on EPA web site: • Chemical addition to waste water with aluminum or iron based coagulants followed by tertiary filtration can reduce total phosphorus concentrates in the final effluent to very low levels. The total phosphorus concentrates achieved by some of these WWTP’s are consistently near or below0. 01 mg/l. • The cost applying tertiary treatment for phosphorus removal is affordable, when measured by the monthly residential sewer fees charged by the municipalities that operate the exemplary facilities.
The monthly residential rates charged to maintain and operates the entire treatment facility ranged from as low as $18 to the highest fee of $46. • There appeared to be no technical or economic reason that
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• Other pollutants that are commonly found affect water quality such as biochemical oxygen demand, total suspended solids, and fecal coliform bacteria are significantly reduced through these advance treatment process. • WWTP’s which utilize enhanced biological nutrients removal (EBNR) in the secondary treatment process can often reduce total phosphorus concentrates to 0. 03mg/l or less prior to tertiary filtration. While employing EBNR is not essential to achieving high phosphorus removal rates, EBNR enhances the performance and reduces operating costs (especially chemicals use) of the subsequent tertiary filtration process.
Recently published studies report that the longer solids retention times used in BNR process also removes a significant amount of other pollutants contained in municipal wastewater, including toxics, pharmaceuticals, and personal care products. • The low effluent turbidity produces by tertiary filtration allows for efficient disinfection offinal effluent without chlorination through the use of ultraviolet treatment. • The treatment process and quality of the final effluent produced by tertiary filtration for phosphorus removal typically meet state criteria for wastewater reclamation.
Reuses of this high quality effluent can be an attractive alternative to direct discharge into surface waters in situation where restrictive NPDES permit limitations apply. The tertiary treatment reduces the BOD/body of waste that collect from the secondary treatment process. It does go beyond secondary treatment according to the Dept of Biotechnology. The heterogeneous microbial community, which includes bacteria, fungi, and protozoa as well as other organisms absorbs and breaks down dissolved organic nutrients in the sewage.
The sewage must rotate and recirculated through porous beds several times through filters in order to reduce the BOD sufficiently.
EPA Report: Advance wastewater treatment to achieve low concentration of phosphorus. Retrieved June 15, 2009. http://yosemite. epa. gov/r10/water. nsf/Water+Quality+Standards/AWT- Dept. of Biotechnology; Method of liquid waste treatment. Retrieved June 15, 2009 http://128. 113. 2. 9/dept/chem-eng/Biotech-Environ/FUNDAMNT/streem/methods. htm