Effect of Greywater Irrigation on Soil Hydraulic Properties
Henry Hartono Gunawan
The use of Greywater for landscaping irrigations is becoming common as Western Australia is experiencing the water restriction due to the current drought condition and critically low level surface water storage. Hence, the reuse of Greywater can utilise the on-site resource, conserve the water efficiently, and reduce the load on wastewater disposal system. As there is still lack of information regarding the effect of surfactants, which are presented especially in the laundry and household detergents, on the hydro-physical soil properties; this project thesis is intended to determine how the laundry greywater can affect the soil properties during irrigation.
Greywater is the wastewater resulted from the domestic activities such as laundry, dishwashing, and bathing in which it can be recycled on-site for land irrigation purpose and others. The surfactants presented in the laundry greywater contain a highly variable chemical depending on the volume of water and chemicals used. Nowadays, Manufacturers have their formulations and marketing strategies that mostly fail to address the problem of potentially hazardous chemicals. In addition, the impacts of pH, salinity, sodium, phoshphorus and sulphur are not addressed in advertising. Moreover, most product labels do not state the ingredients meaning that purchasers can never be sure what is actually in the product.
Considering these issues, this project has been set out to analyse the effect of the greywater irrigation by addressing several factors such as the pH, salinity, electrical conductivity, hydraulic conductivity, surface tension and others. Whereas, the use of appropriate greywater will benefit the gardening which consumes 54 % of the total usage of water in Western Australia
3 REPORT OBJECTIVES
The Aim of this project thesis is to investigate the potential effects of surfactant-rich greywater on soil hydraulic properties during irrigation. In order to accomplish the aim, the project was separated into several objectives;
1) Investigate the composition of the surfactant in laundry greywater A literature review was conducted in order to determine the composition of the surfactant as one of the ingredients of laundry greywater. The surfactant, called as surface active agents, is one of the significant ingredients in the detergent powder. The higher the amount of detergent powder contained in the laundry greywater, the higher the amount of chemical contents (i.e. alkali and chelating agents), which can be damaging to plants and should not be applied to soil. Therefore, it is important to determine the composition of surfactant in order to prevent the excess amount of chemical washed down to the streams.
2) Investigate Particle size distribution of the soil sample Sieve analysis was performed to determine the particle size of the soil sample.
3) Investigate pH and Electrical Conductivity of laundry greywater during irrigation A column experiment (during irrigation process) was carried out to investigate the pH(i.e. acidity) and Electrical Conductivity(i.e. salinity) of the laundry greywater solution. This experiment showed how the different concentration of laundry greywater can have the capability to increase the amount of acidity and salinity. These become an issue as the amount of acidity and salinity need to be limited. The amount of the acidity and salinity of the laundry greywater are specified in laboratory result (i.e. Column experiment during irrigation).
4) Investigate Moisture content, Cappilary rise, Bulk density, and Porosity of the soil sample during irrigation A column experiment (after irrigation takes place) was executed to determine the moisture content, cappilary rise, bulk density, and porosity of the soil sample. For the moisture content, soil sample separation and its weight measurement were...
References: 1. A.H.M. ANWAR, F., BETTAHAR, M., MATSUBAYASHI U. “A method for determining air-water interfacial area in variably saturated porous media”. 1999, Section 2, 3, and 4.
2. “Laundry products research “. Lanfax Laboratories. 2010, http://www.lanfaxlabs.com.au
3. SHAFRAN, A.W., GROSS, A., RONEN, Z., WEISBROD, N., ADAR, E.,. “Potential changes in soil properties following irrigation with surfactant-rich greywater”. Ecol Eng. 2006, Vol. 26:348-54.
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