Evaluation of Recycling Greywater Treated by Granular Filtration System in Arid Areas for Use in Irrigation
Date Issued
2016
Date
2016
Author(s)
Albalawneh, Abeer
Abstract
Wastewater and greywater recycling is an emerging strategy being implemented worldwide to supplement water resource portfolios. Greywater comprises domestic wastewater flows, excluding toilet water. Important aspects of greywater include its characteristics, treatment, reuses, and the environmental impacts associated with its recycled. Finding appropriate greywater treatment methods remains a challenge, since the selection depends on several variables such as greywater quality and quantity, climatic conditions, cost, operating conditions, and the quality requirements associated with the intended use of the treated. This challenge is exacerbated in water scarce, arid or semi-arid countries, such as Jordan. The first goal of this thesis is to develop, install, and validate an efficient, simple, and affordable decentralized greywater treatment method that can be adapted for use by households in arid and semi-arid rural communities for the purpose of restricted agricultural irrigation (grow crops that are not eaten raw by human). Whereas, the second target is to investigate the sustainability of greywater recycling by focusing on the impact of treated greywater irrigation on soil electrical conductivity (EC) and soil quality, after two years of regular use. In addition, it examines perceptions and attitudes of the greywater users, and evaluates their experience practicing greywater treatment and reuse. A review of greywater characteristics and various greywater treatment technologies was conducted. This analysis informed the selection of a constructed wetland treatment system as the suggested on-site greywater treatment system. Therefore, a field study was conducted to collect data about the efficiency of this constructed wetland and to identify the design parameters (i.e., media size, bed dimensions, and plantation types) most suited to arid conditions. The results of this study suggested that non-vegetative beds (granular filter) perform better than the other constructed wetland combinations under these conditions. Using these results, another field study was conducted that focused on the design of a proper granular filtration system (GFS) and evaluated its efficiency as a decentralized greywater treatment system. Our GFS was composed of three treatment stages: pre-treatment (i.e., sedimentation and screening), main treatment (i.e., granular media filtration bed (FB)), and post-treatment (i.e., filtration). Two different local media were tested as FB medium (i.e., volcanic tuff and the gravel). Fifteen GFS were constructed and monitored for two years. Each GFS served a single rural Jordanian home by treating their greywater and recycling it for home garden irrigation. In order to evaluate the efficiency of GFS in greywater treatment, six GFS’s influent and effluent water qualities were monitored. Soil chemical characteristics before and after two years of treated greywater irrigation were compared. In addition, a structured questionnaire was used to collect data from all GFS users about their greywater experience. Our GFSs (using either volcanic tuff or gravel media) adequately treated greywater, as they removed the studied organic contaminants from raw greywater. A GFS that uses volcanic tuff media was more efficient in treating organic contaminants than one that uses gravel media, however, its effluent held a concentration of anions and cations. Despite the quality of GFS effluents was within the permissible limits for restricted irrigation set by the Jordanian standard, further studies are needed to increase the efficiency of the system. Moreover, irrigation using GFSs treated greywater did not have any apparent adverse effects on key soil properties at the studied sites after two years. The average data of all locations monitored showed significant reductions in soil (EC) (the average soil EC before greywater irrigation was 0.97 dS/m and decreased to 0.41 dS/m). All GFS users noticed improvements in their home garden productivity, and about half noticed a reduction in their fresh water consumption.
Subjects
greywater
arid areas
granular filtration system
constructed wetland
soil quality
greywater treatment
Type
thesis
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