Wastewater Recycling In Australia: An Overview

The Hydrological Cycle and Its Significance

All water can be designated to be a recycled water and there is a big chance that even if not all the water molecules, but a part of it has passed through the animals and the human bodies. Also, water present on earth has undergone recycling an innumerable number of times through the natural process called the hydrological cycle. The two different forms of precipitation are the snowfall and rainfall. Water from both rainfall and snowfall eventually flows to the ocean, lakes and rivers (Faccenda et al., 2012). Water then evaporates and rises up to the sky and forms clouds and this returns back to the earth in the form of snow or rain. Some portion of this water percolates into the ground and it remains there unless being pumped else feeds a surface water body. It is a known fact that there are limited sources of fresh water, but the reality is that they are a part of a naturally occurring system. The major issue is that humans tend to utilize the freshwater resources at a faster rate than it can naturally replenish (Fielding, Dolnicar and Schultz 2018). This study will be based on the promoting a wastewater recycling plant and the way of executing the whole plan.

The necessity of wastewater recycling can be summarized as under:

• Recycling wastewater decreases the load of the wastewater on the sensitive ecosystem. In order to reproduce and live, fish, plants and animals rely heavily on the proper flows of water to their habitats. The lack of adequate flow of water is often noticed due to the diversion of water to the industries, urban areas and the agricultural fields. Thus reducing the quality of water reaching to the ecosystem. The users that use water can supplement the increasing demand of water by recycling the wastewater (Grant et al., 2012).
• The recycled wastewater can enhance or create the riparian habitats and the wetlands. The wetlands provide the fishes with breeding grounds, improvement of water quality and sustaining some wildlife habitats. The river or stream have dried up or impaired can be augmented with recycled water and this can, in turn, sustain the wildlife and the aquatic habitat (Luthy et al., 2015).
• Recycling of wastewater is an important step towards the water conservation. Thus, it is important to say that water recycling can meet the environmental, industrial and the domestic demands that are increasing on a daily basis (Pereira, L.S., Cordery and Iacovides 2012).
• Recycling of wastewater provides options for water supplies in the non-potable forms, and it provides a viable option for the potable water. The industries, local business receive and dependable and inexpensive water supply (Opher and Friedler 2016).
• Recycling of wastewater provides an added option to not to pump out water from the groundwater resources. This saves the energy and this, in turn, utilizes less energy, improves the air quality and produce fewer greenhouse gases (Schmidt et al., 2013).

The water recycling in Australia involves the water reclamation for the purpose of non-potable and potable use of water, this is supplied back to the water system either indirectly or directly. The major area of concern is of water security and it includes the variable and dry climate especially in the city and the urbanized areas. Thus, recycled water is the most economically sound, climate resilient, and a reliable source of water.

 The various sources from where the wastewater is recycled are the greywater from the households and stormwater harvesting (Atse.org.au 2018).

The ministerial councils involving health portfolios, agricultural portfolios, the Ministers of New Zealand that are responsible for the environment, commonwealth territories and states. All these ministerial councils are guided and led by the National Health and Medical Research Council and Environment Protection and Heritage Council for the purpose of developing a National Water Quality Management and Strategy Guidelines for water recycling. Figure 1 shows the Wastewater recycling in Australia 2009/10 in ML/year. The water recycling guidelines are being released after making an extensive referral which was under different phases. The Phase I involves management of environmental and health risks (2006), drinking water supplies and its augmentation (2008), stormwater reuse and harvesting (2009), recharge of a managed aquifer (2009). In the year 2011, the Australian Drinking Water Guidelines were reframed and redeveloped by the National Health and Medical Research Council along with the collaboration of national Resource Management Ministerial Council. The guidelines framed are typically based on the Hazard Analysis and Critical Control Point principles. Under the constitution, the territories and the states have the responsibility for the water resources and thus the guidelines are incorporated into the regulatory system (Radcliffe 2015).

Necessity of Wastewater Recycling

Figure 1: Wastewater recycling in Australia 2009/10 in ML/year [source: Awa.asn.au 2018a]

According to the AWA/Deloitte State of the Water Sector Report 2014, it has been found that professionals of the water sector were largely supportive of water recycling. As per the support, 97 percent somewhat agreed, agreed, strongly agreed to the water recycling and this provides a sustainable source of non-potable water for both the industrial and municipal use. However, this percentage reduced to 87 percent that agreed that the recycled water can be managed and treated to a sufficient level where the water is safe for drinking.

Figure 2: a survey conducted on recycled water as a means to ensure a secure supply of water. [source: Awa.asn.au 2018b]

According to the survey conducted, the respondents in Victoria showed that there is a higher level of soundness and satisfaction on the water sector. Around 89 percent of the respondents have shown that the due to the climate change there will be a significant change in the water sector. Victorians have supported for the systems that will be able to withstand the extreme events and weather conditions. The Victorian respondent has raised the issue that the water must be returned to the environment, it must be ensured that the rural and urban areas receive ample supply of water (Awa.asn.au 2018b). Water pricing issues is a major topic of discussion and the survey conducted in the year 2014 have highlighted that fact that the rising prices of water are a major concern and in some of the states, the prices are considerably high. In South Australia, the price rise is a major issue and since the year 2012, the situation is aggravating. 

How the system will work: the water recycling process uses very fundamental principles based on the chemical, biological and physical principles to remove all the contaminants that are present in water. the physical or the mechanical processes that are used for the treatment of wastewater is referred to as the primary treatment. The biological process that provides the further treatment of the wastewater is called the secondary treatment. The additional processes of purification are called the advanced treatment process or the tertiary process. 

Figure 3: Wastewater recycling plant flowchart (done by the author)

Primary treatment: The primary treatment process will include the simple physical and the mechanical processes in order to remove the about half of the contaminants from the wastewater.

1. Bar screens- in the first stage of the recycling process, the incoming sewage will have moved through the mechanical screens and this will remove the plastic material, rags, sticks and other large solid materials from the wastewater stream. A horizontal conveyor belt will take the captured materials from the collection area into the dumpster and will be removed later and used as a landfill.
2. Grit chamber- In the next stage, the wastewater flow moves to the aerated grit chamber and in order to settle the grit particles, the stream is saturated with the fine air bubbles.
3. Primary clarification- the wastewater moves to the primary clarifiers. The velocity of flowing stream of waste water promoted the settling of the solids. The biosolids that are removed at this point are dewatered and digested and they are used for different purposes like conditioning soil and composting (Saws.org 2018).

Secondary treatment: this step utilizes the micro-organisms that remove a majority of the contaminants remaining in the soil. This process explicitly deals with the growing microorganisms.

1. Aeration basins- In this step, wastewater moves into the chambers called aeration basins and in this particular chamber, waste water is mixed with oxygen. The organic material present in the wastewater is digested by bacterial microorganisms inside the wastewater and consider them as food. These microorganisms are then collected into the final clarifiers which end ups as biosolids.
2. Final clarifiers- the majority of the solid materials that settle down into the final clarifiers are then thickened and digested subsequently. Some of the microorganism population are the return to the aeration tank. These microorganisms are then returned to the incoming water to feed on the wastewater (Saws.org 2018).

Advanced treatment and disinfection: after the previous step, water is filtered through the sand which in the later part undergoes chemical disinfection when the wastewater passes through the chlorine contact chambers. Chlorine is then removed with the help of Sulphur dioxide.

1. Sand filters- The flow then enters the final clarifiers and the particulate matter is filtered out once it enters the sand filters. It is one of the common step of gravity filtration system. This process has an advantage over the gravity filter technique and is the process can be easily observed visually. Between the disinfection and final clarifier, sand clarifiers are placed.
2. Dechlorination and disinfection- After the chlorination process which takes about 20 minutes to ensure that the all pathogenic organisms are destroyed. The stream is then dechlorinated with the Sulphur dioxide.
3. Outfall- this is the last step and is fully treated and recycled water is then released into the environment. The point or the place where the recycled water is discharged into the water body is called outfall (Saws.org 2018).

Solids processing: biosolids are the by-products that are finally set aside during the wastewater recycling process. The biosolids can be used as natural organic fertilizer and soil conditioner. The biosolids are compacted using techniques called de-watering, anaerobic digester, thickener.

Risks that are addressed- The identified risks were the price rise experienced due to the increasing cost of the wastewater treatment process. While the treatment procedure that is proposed is very basic and it can have the added benefit of the less complex process. On the other hand, the efficient process is cost-effective with respect to the larger plants that have technical complexities. The end products can effectively be used to generate revenue and can be used as a natural organic fertilizer and soil conditioner.

Conclusion

From the above discussion, it can be concluded that Recycling wastewater decreases the load of the wastewater on the sensitive ecosystem. The water recycling guidelines are being released after making an extensive referral which was under different phases. The Phase I involves management of environmental and health risks (2006), drinking water supplies and its augmentation (2008), stormwater reuse and harvesting (2009), recharge of a managed aquifer (2009). Water pricing issues is a major topic of discussion and the survey conducted in the year 2014 have highlighted that fact that the rising prices of water are a major concern and in some of the states the prices are considerably high. In South Australia, the price rise is a major issue and since the year 2012, the situation is aggravating.

References

Atse.org.au, 2018. Water Recycling in Australia. [online] Atse.org.au. Available at: https://www.atse.org.au/Documents/reports/water-recycling-in-australia.pdf [Accessed 28 Aug. 2018].

Awa.asn.au, 2018a. Water Recycling Fact Sheet. [online] Awa.asn.au. Available at: https://www.awa.asn.au/AWA_MBRR/Publications/Fact_Sheets/Water_Recycling_Fact_Sheet/AWA_MBRR/Publications/Fact_Sheets/Water_Recycling_Fact_Sheet.aspx?hkey=54c6e74b-0985-4d34-8422-fc3f7523aa1d [Accessed 28 Aug. 2018].

Awa.asn.au, 2018b. AWA/Deloitte State of the Water Sector Report 2014. [online] Awa.asn.au. Available at: https://www.awa.asn.au/Documents/State_of_the_Water_Sector_Report_2014_FINAL.pdf [Accessed 28 Aug. 2018].

Faccenda, M., Gerya, T.V., Mancktelow, N.S. and Moresi, L., 2012. Fluid flow during slab unbending and dehydration: Implications for intermediate?depth seismicity, slab weakening and deep water recycling. Geochemistry, Geophysics, Geosystems, 13(1).

Fielding, K.S., Dolnicar, S. and Schultz, T., 2018. Public acceptance of recycled water. International Journal of Water Resources Development, pp.1-36.

Grant, S.B., Saphores, J.D., Feldman, D.L., Hamilton, A.J., Fletcher, T.D., Cook, P.L., Stewardson, M., Sanders, B.F., Levin, L.A., Ambrose, R.F. and Deletic, A., 2012. Taking the “waste” out of “wastewater” for human water security and ecosystem sustainability. science, 337(6095), pp.681-686.

Luthy, R.G., Sedlak, D.L., Plumlee, M.H., Austin, D. and Resh, V.H., 2015. Wastewater?effluent?dominated streams as ecosystem?management tools in a drier climate. Frontiers in Ecology and the Environment, 13(9), pp.477-485.

Opher, T. and Friedler, E., 2016. Comparative LCA of decentralized wastewater treatment alternatives for non-potable urban reuse. Journal of environmental management, 182, pp.464-476.

Pereira, L.S., Cordery, I. and Iacovides, I., 2012. Improved indicators of water use performance and productivity for sustainable water conservation and saving. Agricultural water management, 108, pp.39-51.

Radcliffe, J.C., 2015. Water recycling in Australia–during and after the drought. Environmental Science: Water Research & Technology, 1(5), pp.554-562.

Saws.org, 2018. SAWS: Water Recycling Treatment Process. [online] Saws.org. Available at: https://www.saws.org/Your_Water/Recycling/Centers/treatment.cfm [Accessed 28 Aug. 2018].

Schmidt, S., Geyer, T., Marei, A., Guttman, J. and Sauter, M., 2013. Quantification of long-term wastewater impacts on karst groundwater resources in a semi-arid environment by chloride mass balance methods. Journal of hydrology, 502, pp.177-190.