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WRRCTR No.130 Recycling of Sewage Effluent by Sugarcane Irrigation: A Dilution Study, October 1976 to October 1978, Phase II-A

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Title:WRRCTR No.130 Recycling of Sewage Effluent by Sugarcane Irrigation: A Dilution Study, October 1976 to October 1978, Phase II-A
Authors:Lau, L. Stephen
Ekern, Paul C.
Loh, Philip C.S.
Young, Reginald H.F.
Dugan, Gordon L.
Keywords:water reuse
sewage effluent
furrow irrigation
show 8 morefield tests
sugar yields
Lahaina soil
tropeptic haplustox
show less
LC Subject Headings:Sewage irrigation -- Hawaii -- Oahu.
Sugarcane -- Irrigation -- Hawaii -- Oahu.
Water reuse -- Hawaii -- Oahu.
Date Issued:Mar 1980
Publisher:Water Resources Research Center, University of Hawaii at Manoa
Citation:Lau LS, Ekern PC, Loh PCS, Young RHF, Dugan GL. 1980. Recycling of sewage effluent by sugarcane irrigation: a dilution study, October 1976 to October 1978, phase II-A. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 130
Series:WRRC Technical Report
Abstract:This study is an extension of the project, "Recycling of Sewage Effluent by Irrigation: A Field Study on Oahu," completed in July 1975. The major objective of this portion was to determine the dilution with Waiāhole Ditch water necessary for optimal sugar yield when chlorinated, secondarily treated sewage effluent was used for furrow irrigation of cane. Hawaiian sugarcane variety 59-3775 was planted in October 1976 to a random-block design of treatments with six replicates in Oahu Sugar Company's Field No. 246 in central O’ahu near the Mililani Sewage Treatment Plant. The five irrigation treatments for the 2-yr cane cycle were (1) ditch water; (2) 12.5%; (3) 25%; (4) 50% effluent diluted with ditch water; and (5) effluent the first year and ditch water the second year. The ripener "Polaris" was applied prior to harvest which was completed in October 1978. Crop logs monitored the cane growth and test plots were hand harvested for assessment of cane and sugar yield. Porous plastic tubes were used to sample soil water percolate for chemical analyses. The sewage effluent and the percolate were checked for the presence of human enteric viruses. Sugar yields for effluent concentrations up to 25%, or for effluent the first year and ditch water the second year, were equal to those from conventional ditch-water irrigation. There was a significant loss in juice quality and sugar yield for the 50% effluent concentration. The correlation coefficient between effluent concentration and cane yield was +0.66; between effluent and juice quality, -0.99; and between effluent and sugar, -0.86. The irrigation was equivalent to an annual average of approximately 2.03 m (80 in.)/yr and would thus require 6.8 x 10^5 m^2 (167 acres) for each 0.04 m^3/s (1 mgd) of undiluted output from the Mililani plant. Immediately after each application of fertilizer and also with effluent concentrations of 50 to 100%, the nitrate nitrogen concentrations in the percolate exceeded the critical level of 10 ppm for potable water. An estimated 55% of the irrigation percolated beyond the root zone and from 0.008 to 0.028 kg/m^2 (69.3-254.3 lb/acre) of nitrate since the total applications far exceeded the ability of the sugarcane to take up nitrogen. An unexplained nitrogen deficit of 0.013 to 0.038 kg/m^2 (115-338.6 lb/acre) was assigned to gaseous nitrogen loss. No virus was recovered from the test plots, although 40% of the samples from the effluent reservoir were positive. At least 96% of the virus was inactivated after 1 day of storage.
Pages/Duration:xi + 107 pages
Appears in Collections: WRRC Technical Reports

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