Impact of recycled water irrigation on soil salinity and its remediation

Continuous use of recycled water (treated wastewater) over a long period of time may lead to the accumulation of salt in the root zone of the soil. This is due to the relatively higher levels of salt contained in the recycled water compared to a town water supply. The increase in salt concentration in the soil can adversely influence the amount of water a plant can uptake from the soil due to the osmotic effect. Despite significant benefits, recycled water may deteriorate soil health in terms of increased salinity and sodicity. Although several studies in the past have highlighted the increase of soil salinity due to recycled water irrigation, the phenomenon depends on the variability of soil characteristics. In this study, the impact of using three different types of irrigation water (with electrical conductivity 0.2, 0.8, and 2.0 dS/m) on the mechanism of salt accumulation in the soil was investigated. To contribute to the addition of the existing knowledge of soil salinisation, soil from two paddocks (i.e., D33 and Yarramundi) in Western Sydney, Australia were analysed, and relationships among parameters associated with salt accumulation were evaluated using the results from continuous column studies. Results show that if the irrigation is conducted with high saline water, there is a possibility for salinisation of soil to occur. To prevent this from occurring, one of the solutions could be to use a normal town water supply for irrigation at some intervals. This will allow for the leaching of excess salt accumulated in the soil to deeper layers

Proceedings of the 1st International Conference on Water and Environmental Engineering (iCWEE2017), 20-22 November 2017, Sydney, Australia

The International Conference on Water and Environmental Engineering aims to provide an international platform for effective exchange of ideas, reaffirming the existing collegial contacts, provide opportunities for establishing new ones as well as providing a forum for academics and researchers to present and share the results and findings of their latest research and practice on a wide range of topics relevant to water and environmental engineering

Proceedings of the 3rd International Conference on Water and Environmental Engineering (iCWEE-2022), 27-30 November 2022, Sydney, Australia

The 3rd International Conference on Water and Environmental Engineering aims to provide an international platform for effective exchange of ideas, reaffirming the existing collegial contacts, provide opportunities for establishing new ones as well as providing a forum for academics and researchers to present and share the results and findings of their latest research and practice on a wide range of topics relevant to water and environmental engineering

Sustainable water use in construction

Water is needed in direct construction activities and also for the production of construction materials as embodied water. Water use during the life time of an infrastructure also needs to be considered in the planning and design phase of the infrastructure to save and conserve water in the long run. A typical building is associated with water use in direct and indirect forms. Direct forms include water consumed by workers, water used in washing aggregates, preparing raw concrete, curing concrete, dust suppression and washing of hard surfaces and equipment. Indirect use is related to embodied water, which has been used in production of construction materials. Use of water-efficient devices can save significant volumes of water during the operation phase of a building. It is expected that a greater environmental awareness, favorable government policy and continuing education will enhance the water use efficiency in the construction industry

Regional flood frequency analysis : investigation of GEV distribution with L-moments for South East Australia

Identification of an appropriate statistical distribution is a fundamental step in Regional Flood Frequency Analysis (RFFA) that finds the most appropriate distribution to the observed annual maximum flood data and lead to accurate quantile at a single site. Parameter regression technique (PRT) is a regression technique that relates the parameters of a probability distribution (i.e. location, scale and shape to the mean, standard deviation and skewness of the flood data) to catchment characteristics. The Generalised extreme value (GEV) and Log Pearson type III (LP 3) distributions have been identified by several studies as the top best-fit distributions in RFFA. However, in Australia, P RT-GEV method has not been tested for RFFA. In this paper, GEV distribution has been investigated and its parameters have been estimated using L-moments for 176 catchments from New South Wales (NSW), 186 catchments from Victoria and 196 catchments from Queensland (QLD). Goodness of fit tests and L-moment ratio diagram were used to examine how GEV can fit the maximum flow data. It has been found that most of the catchments are dominated by negative shape parameters. GEV with L-moments seemed to be good candidate distribution to fit annual maximum flood data for NSW, QLD and VIC

Irrigation in urban landscapes : effectiveness of recycled water for sporting fields

This study aims at evaluating the effect of applying different types of recycled water on Kikuyu grass which is a very popular turf grass used for Australian urban lands as well as sporting fields. Three identical columns were irrigated with tap water (TW) as control water and two types of treated wastewater namely MBR (Membrane Bioreactor) and IDAL (Intermittently Decanted Aerated Lagoon). Salinity level for both treated wastewaters was similar while MBR had a higher level of nutrients compared to IDAL. Grass dry matter yield and nutrient level were monitored and analysed regularly. The highest dry matter yield was achieved from the column irrigated with MBR. The second highest dry matter yield obtained from potable water and amount of dry matter yield from IDAL was far lower than the other two columns. Based on these results, it can be concluded that it is more beneficial to sue secondary treated wastewater for irrigation of urban lands, thus saving in water and chemical fertilisers. Moreover, significant saving in the treatment costs can be achieved by not adopting tertiary of advanced treatment system

The effect of irrigation using recycled waters obtained from MBR and IDAL wastewater treatment systems on soil pH and EC under kikuyu grass (Pennisetum clandestinum) production

The main objective of this study was to determine the effect of irrigation using three different types of waters, viz. treated wastewater through membrane bioreactor system (MBR), treated wastewater via intermittently decanted aerated lagoon process (IDAL) and tap water (TW) on soil pH and EC under kikuyu grass production. No fertiliser was added during the study period (one year). Irrigation waters, waters extracted from different soil depths and soil samples from different depths were analysed in laboratory. Considerable changes occurred in soil characteristics over the study period under the various treatments. Soil pH increased more than 1 unit under irrigation with treated wastewater produced by IDAL system while soil irrigated with treated wastewater from MBR treatment system showed little change and TW irrigated soil evidenced a slight decrease when compared to pH at the beginning of the study. Also, a remarkable increase was recorded for EC1-5 of top soils irrigated with treated wastewaters compared to soil's initial EC. The results from this study highlighted the benefits of irrigation with treated wastewater through MBR system due to its lower cost of treatment compared to IDAL process while providing additional nutrients such as nitrogen and phosphorus form the wastewater

Variation in kikuyu grass yield in response to irrigation with secondary and advanced treated wastewaters

Treated wastewater, also called as recycled water, is a reliable source of water for various non-potable purposes. One of the most common uses of recycled water has been for irrigation. A soil column study was carried out for a period of one year. The objective of this study was to determine the effect of irrigation using two different types of treated wastewaters on kikuyu grass (Pennisetum clandestinum) production in the absence of any kind of chemical fertilisers. Soil irrigated with secondary treated wastewater, MBR (Membrane Bioreactor), resulted in highest annual grass production (16,241 kg of dry-matter per hectare (kg DM/ha)) compared to advanced treated wastewater, IDAL (Intermittently Decanted Aerated Lagoon), and tap water (TW) with annual yields of 7028 and 14,216 kg DM/ha, respectively. Irrigation waters, soil extracted waters and soil samples from different depths of the columns were analysed. Sodium adsorption ratio (SAR), exchangeable cations, electrical conductivity (EC) and pH changed in each experimental column due to different characteristics of applied irrigation waters. The results indicate that high contents of nitrogen and phosphorous in MBR water compensated for the presence of moderate salinity level that contributed to the higher production of grass compared to other two types of irrigation waters. The increase in pH from initial amount of 5.9 to 7.3 in top part of IDAL-irrigated soil may have resulted in low grass yield. This pH increase can be attributed to the high concentrations of cations in the irrigation water in the lack of sufficient amount of nitrogen. Overall, the study demonstrated that a relatively higher grass yield in the absence of any types of fertilisers is possible with recycled water irrigation using secondary treated wastewater. Further, the recycled water irrigation with advanced treatment of wastewater, while costs more, does not result in increased yield benefits

Potential to produce poultry feed from food wastes

The annual food waste in Australia is estimated at 7.5 million tonnes with the majority disposed of in landfills. This not only causes significant economic loss but also has a negative environmental impact. This study aimed at investigating the possibility of recycling food waste into feed for poultry. Nutrient contents of various waste streams were evaluated. The food waste collected from the services club and restaurant contained the highest levels of crude protein and crude fat ( 404 g/kg and 278 g/kg, respectively) while crude protein and crude fat content of food waste originating from bakeries and fruit-vegetable growers were 100 g/kg and 43 g/kg, respectively. The findings indicated that the blended material had an excessive Na concentration (6.5 g/kg), low Ca content (1.0 g/kg) and high/low concentrations of other nutrients relative to broiler grower feed requirements. Further studies are required to investigate the blending of waste streams with other nutrient sources to meet nutrient requirements. Microbial contamination, free fatty acids, oxidation and nutrient digestibility need to be considered before valuable recycled food wastes can be used as a feed source for poultry