Utilization of Reclaimed Wastewater for Irrigation and Urban Activities in Okinawa Island, Japan

Dayanthi, W. K. C. N.; Shigematsu, Takeshi; Tanaka, Hiroaki; Yamashita, Naoyuki; Kato, Koichi; Silva, Viraj de

doi:10.2175/193864706783749981

Cited by 4 publications

(10 citation statements)

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“…Since there are no criteria for the agricultural use of RWW in Japan, California reuse Criterion "Title22" (CDHS 1978), that is one of the most stringent standards of wastewater reclamation in the world, is planned to be applied to protect public health (Dayanthi et al 2006a). The "Title 22" system has been preferred owing to the fact that the treatment train described in "Title 22" seems guaranteeing the sufficient safety for pathogenic infectious risks represented by enteric viruses, which may occur due to uncooked vegetables irrigated with RWW (Tanaka et al 1998).…”

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

“…They may adversely affect the crop cultivation, as well as the environment such as soil and ground water as a result of the long-term irrigation. Especially in the case of SD, the average ammonium content of RWW is 18mgN/L because of the absence of a nitrification/denitrification unit process in the experimental reclamation facility (Dayanthi et al 2006a).…”

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

“…To confirm the applicability of the criteria considering the difference of climate and wastewater treatment process between California and Okinawa, the experimental reclamation facility was built in 2002, and many experiments, based on the human health, crop quality and adverse environmental effects, have been conducted since then (Dayanthi et al 2006a). The issues of pathogenic microorganisms and hazardous chemicals, which directly affect the human health, need the prime attention.…”

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

“…The Cabinet Land Improvement General Office (CLIGO) of Okinawa General Bureau has mainly conducted the long-term monitoring. Dayanthi et al (2006a) stated that though the CLIGO had conducted several cultivation experiments on the field lysimeters to investigate the adverse environmental issues, the fate of the contaminants originating from the RWW had not been understood well.…”

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

“…The secondary treated wastewater from Naha WWTP is first directed to the coagulation and sedimentation with PAC (Poly Aluminium Chloride) in order to remove suspended solids, pathogens and phosphorus (Dayanthi et al 2006a). Then the effluent is directed to two wastewater characteristics and the disinfection efficiency.…”

Section: Experimental Reclamation Facility In Okinawamentioning

confidence: 99%

See 4 more Smart Citations

The first introduction of reclaimed wastewater to dry-farming field in Okinawa Island, Japan

Shigematsu

Dayanthi

Yamashita

et al. 2008

Water Science and Technology

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Reclaimed wastewater (RWW) will be introduced to the first large-scale irrigation project for dry-farming on Okinawa Island, Japan. The wastewater reclamation for agricultural use sounds attractive to the water resource management. Since there are no specific standards for the RWW irrigation, the monitoring and other demonstrative experiments have been conducted using the experimental reclamation facility, which is based on the criteria "Title22". The experiments showed that the existing system is sufficient to meet the above criteria of pathogens, protozoa and viruses, and the concentrations of hazardous chemicals are lower than the environmental standards in Japan. In addition, several laboratory soil column experiments were conducted to address the environmental issues. An increase of denitrification due to the continuous irrigation was observed. Salt and nitrate accumulation in the surface soil was observed as well. We can conclude that the RWW of the above facility assures the safety for human health, and further research based on environmental issues is needed in addition to an integrated risk assessment and communication.

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Section: Monitoring and Demonstrationsmentioning

confidence: 99%

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

Section: Monitoring and Demonstrationsmentioning

confidence: 99%

Section: Experimental Reclamation Facility In Okinawamentioning

confidence: 99%

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The first introduction of reclaimed wastewater to dry-farming field in Okinawa Island, Japan

Shigematsu

Dayanthi

Yamashita

et al. 2008

Water Science and Technology

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Numerical modeling of groundwater flow and nitrate transport in karst and wastewater irrigated agricultural and forest landscapes, PA, USA

Daniel,

Richendrfer,

Falta

et al. 2023

Agrosystems Geosci & Env

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Understanding the influence of treated wastewater reuse for irrigation on nitrate groundwater contamination in karstic landscape is critical for developing long‐term management plans and assessing the sustainability of these practices. The Pennsylvania State University has been operating a secondary treated wastewater effluent irrigation site—the “Living Filter”—since the 1960s. The objective of this study is to develop a regional groundwater flow and nitrate transport model to assess the impact of treated wastewater and disposal of large volumes of wastewater for irrigation of agricultural and forested lands on nitrate groundwater contamination in a karst landscape in the Spring Creek Watershed in central Pennsylvania. The modular three‐dimensional finite‐difference ground‐water flow model (MODFLOW) was used to construct the groundwater flow model of the local aquifer and simulate three‐dimensional regional changes in the water table over time. The simulation of nitrate fate and transport in the aquifer was conducted by developing a groundwater mass transport model using MODFLOW and a modular three‐dimensional transport multi‐species model (MT3DMS). The calibrated groundwater model yielded a root mean square error of 5.41 ft for the area of irrigation and 24.67 ft for the entire modeled area. Results of the calibrated model show the extension of a nitrate plume over most of the study area with concentrations below 10 mg·L−1 under the current 2015 setting and the long‐term 2035 scenario of increased irrigation rates. The nitrate migration was dominated by the presence of two high conductivity groundwater troughs adjacent to the study area resulting in a near steady‐state total mass since the 1990s.

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Water quality comparison of secondary effluent and reclaimed water to ambient river water of southern Okinawa Island via biological evaluation

Mano

Takeda

Kitamura

et al. 2017

Environ Monit Assess

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The objective of this work was to evaluate the biological effect of the secondary effluent (SE) of a wastewater treatment plant and reclaimed water treated via ultrafiltration (UF) followed by either reverse osmosis (RO) membrane filtration or nanofiltration (NF) to be used for environmental use by comparing the results of algal growth inhibition tests of concentrated samples of the SE and permeates of RO and NF with those of six rivers in southern Okinawa Island. Although the SE water had no adverse effects on the growth of the algae Pseudokirchneriella subcapitata, it could lead to water quality degradation of rivers in terms of its toxic unit value, whereas the use of RO and NF permeates would not lead to such degradation. The recharge of rivers, into which domestic wastewater and livestock effluents might be discharged in southern Okinawa Island, with reclaimed water subjected to advanced treatment could dilute the concentrations of chemicals that cause biological effects and improve the water quality of the rivers, based on the results of the bioassay using P. subcapitata. Comparing the results of bioassays of reclaimed water with those of the ambient water at a site might be effective in assessing the water quality of reclaimed water for environmental use at the site.

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Utilization of Reclaimed Wastewater for Irrigation and Urban Activities in Okinawa Island, Japan

Cited by 4 publications

References 0 publications

The first introduction of reclaimed wastewater to dry-farming field in Okinawa Island, Japan

The first introduction of reclaimed wastewater to dry-farming field in Okinawa Island, Japan

Numerical modeling of groundwater flow and nitrate transport in karst and wastewater irrigated agricultural and forest landscapes, PA, USA

Water quality comparison of secondary effluent and reclaimed water to ambient river water of southern Okinawa Island via biological evaluation

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