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Title: Wastewater treatment by a prototype slow rate land treatment system
Authors: Jenkins, Thomas F.
Palazzo, A. J. (Antonio J.)
Keywords: BOD
Organic carbon
Trace organics
Plant uptake
Wastewater treatment
Forage grasses
Plant yields
Water pollution
Land treatment
Slow rate
Water quality
Suspended solids
Water volumes
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: CRREL report ; 81-14.
Description: CRREL Report
Abstract: Six slow rate land treatment prototypes, three containing a Windsor sandy loam and three containing Charlton silt loam, were studied from June 1974-May 1980. The systems were spray irrigated with either primary or secondary wastewater at application rates ranging from 2.5 cm/wk to 15 cm/wk. Application schedules were also varied. The performance of forage grasses was studied to determine the yield and nutrient uptake under the various application regimes. The results indicate that, on a mass basis, an average of 91% of the nitrogen (N) applied could be attributed to either plant uptake or percolation of soluble N, mainly nitrate. Nitrate concentrations in the percolate were found to correlate with N loading rate. An N loading rate of 800 kg/ha resulted in a mean concentration of about 10 mg/L of N03-N in the percolate. Plant uptake of N was linearly related to N loading rate at loading rates less than 800 kg/ha. In this range, plant uptake accounted for about 60% of the N applied. Mean phosphorus (P) concentrations in the percolate were found to range from 0.03 to 0.07 mg/L P and depended only slightly on application rate. Removal of P averaged greater than 99% for all application regimes. Water balance measurements indicate that evapotranspiration exceeded pan evaporation by a factor ranging from 0.86 to 1.17 over a 6-year period. Treatment of biochemical oxygen demand (BOD5), suspended solids, total organic carbon (TOC), and fecal coliform were excellent. Residual levels of BOD5, suspended solids, and TOC in the percolate averaged 1.3, 1.2 and 1.8 mg/L, respectively. Fecal coliform bacteria in the percolate were reduced to detection limits independent of whether the wastewater was pretreated or disinfected before application. A significant reduction in chloroform and other volatile trace organics was also found. Mean concentrations of chloroform were reduced from 9.6 µg/L in the chlorinated primary wastewater to about 0.2 µg/L in the test cell percolates. No significant downward movement of heavy metals was found 5 years after suspension of heavy metal application. Potassium (K) fertilization was found to be necessary to balance the low K/N ratio of the wastewater.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:CRREL Report

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