FACTSHEET – Biosolids Profile
Note: The National Waste Report2010did not cover biosolids, although data presented for some jurisdictions included disposal figures for biosolids.
What are biosolids?
Biosolids are the treated organic solids produced by waste water treatment processes which may be used for beneficial uses. The extent of dewatering and/or drying of biosolidsvaries from facility to facility. This in turn affects the amount of liquid in biosolids.State and territory definitions of biosolids may vary.
Treatment of data in reporting
The Liquid Waste Assessment[1]concluded that the liquid waste content in biosolids represents a potentially substantial interface of liquid and solid waste data sets which may result in potential ‘double counting’ between solid and liquid waste data accounting. The Liquid Waste Assessment recommended that where liquid waste reporting occurs in parallel to solid waste reporting, biosolids be excluded from the scope of solid waste reporting and be included in liquid waste reporting (regardless of their physical state, wet or dry). Biosolids represent a recovered volume of waste from the sewerage waste system. However, if liquid waste is not reported then biosolids data inclusion in solid waste data is appropriate.
Management of biosolids
The treatment and use of biosolids is regulated by states and territories. The final management options for biosolids may be split into two main categories: beneficial useor disposal. Figure 1 below illustrates a number of typical pathways in the production and treatment of biosolids from wastewater to beneficial use or disposal, although there are many alternatives to these processes.
Figure 1 Typical pathways in the production and handling of biosolids[2].
Biosolids may contain pathogenic microorganisms and contaminants such as synthetic organic compounds and toxic metals. However, with appropriate management of the human and environmental health risks, biosolids may be used for beneficial uses as they contain valuable constituent components including:
- macronutrients, such as nitrogen, phosphorus, potassium and sulphur.
- micronutrients, such as copper, zinc, calcium, magnesium, iron, boron, molybdenum and manganese.
- organic matter.
- inorganic matter[3].
These components mean that biosolids can be used effectively as a fertiliser, soil conditioner or soil replacement product. A reduced reliance on inorganic fertilisers has an additional environmental benefit as the production of these fertilisers also results in carbon emissions. Every tonne of biosolids used in agriculture to replace inorganic fertilisers is estimated to avoid up to six tonnes of carbon dioxide that would otherwise be emitted in the production process[4].
The Australian water industry and its regulators are working to effectively identify, assess and sustainably manage biosolidissues, including through the Australian and New Zealand Biosolids Partnership (ANZBP) which consists of utilities, consultants, academicsand government representatives managed by the industry body, the Australian Water Association[5].
Sustainably managing biosolids is important because of:
- theincreasing cost of biosolids management.
- community expectation that there will be improved utilisation of biosolids as a resource.
- thechanging and increasingly stringent regulation of products such as biosolids.
- the larger quantities and differing properties of biosolidsbeing produced due to improvements in sewage treatment processes.
Biosolids management challengesinclude:
- increasing transport costs due to increased fuel prices and increasing volumes of biosolids production .
- identifying viable land application sites that are both appropriate and within cost effective transport distances. These sites are becoming less available due to urban development.
- managing the odour concerns that the community has about biosolids remains a challenge for the beneficial use of biosolids.
- stockpilingand landfilling can result in the production of greenhouse gases, including methane[6][7]. The extended storage of biosolids in stockpiles may also result in the loss of nutrients such as nitrogen and phosphorus[8].
The ANZBPcommissioned national surveys on biosolids in 2009–10 and 2012–13 to collect information on the production and final management of biosolids in Australia. Both surveys included a total of 322 sites, representing approximately 80 per cent of Australia’s population[9].
Total biosolid production in Australia was approximately 330000 tonnes of dry solids in 201213 compared with 300000 tonnesin 2009–10. The increase reflects incremental change over the period and some changes in the survey design between the two surveys. Figure 2 presents a breakdown of the biosolid production by state and territory.
Figure 2Biosolids production by state and territory in 2012–13[10].
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The amount of biosolids produced is dependent on a range of factors, including the physical wastewater/sludge treatment process and where the waste water is collected from i.e. domestic and industry sources. Thus figure 2 is not a direct reflection of state or territory population.
The ANZBP 2012–13 biosolids survey applied the following broad classifications to categorise the end use or treatment of biosolids:
- Agriculture: for biosolids applied as a fertiliser without value added processing.
- Forestry: for biosolids applied as a fertiliser to plantation forests.
- Land rehabilitation: for biosolid use for rehabilitation such as of mine sites (a new category that was not used in the 2010 survey).
- Landscaping (compost): for biosolids processed in a composting facility and then used for landscaping or another horticultural use.
- Stockpile: where biosolids were stored, awaiting further processing, use or disposal.
- Landfill: for biosolids disposed of to landfill.
- Ocean discharge: for biosolids disposed of into the ocean.
- Other uses: to those set out above.
- Unspecified: where sewage treatment plants did not respond or where the end treatment or use could not be identified.
The breakdown of biosolids production and use or treatment by jurisdiction, is provided in Table 1.
Table 1Biosolids use/treatment by jurisdiction in dry tonnes in 2012–13 (tonnes per annum)[11].
Agriculture / Landscaping (compost) / Land Rehabilitation / Landfill / Ocean discharge / Stockpile / Unspecified / Other / TOTALNSW & ACT / 49132.0 / 157245.0 / 8577.5 / 1499.5 / 3942.0 / 238.5 / 4416.5 / 14600.0 / 98130.5
QLD / 62556.0 / 2263.0 / 2961.5 / 2391.5 / 70172.0
SA / 30477.5 / 30477.5
TAS / 2993.0 / 473.0 / 3359.5 / 6825.5
VIC / 29617.0 / 2690.0 / 962.0 / 62051.0 / 317.0 / 95638.0
WA & NT / 20440.0 / 2007.5 / 2874.5 / 2935.0 / 28256.5
TOTAL / 195215.5 / 20895.5 / 11802.5 / 10695.0 / 3942.0 / 65224.5 / 6808.0 / 14917.0 / 329500.0
Nationally in 2012–13, 59 per cent of biosolids producedwere applied to agricultural land (195215.5 dry tonnes of biosolids). Stockpiling treatment made up the second highest proportion of total biosolids, 65224.5 dry tonnes of biosolids or 20 per cent. The stockpiling national figure is strongly influenced by the quantity of biosolids that Victoria stockpiled, which represented 73 per cent of its biosolids production and 95 per cent of the national figure in 2012–13.
Biosolids in Victoria
“Until recently, many of the biosolids in Victoria have not met or been able to pass all of the Environment Protection Authority Victoria’s (2004) Guidelines for Environmental Management - Biosolids Land Application reuse quality requirements.Biosolidswere therefore unable to be beneficially used. Unlike many other treatment plants, due to the scale of the plants in Melbourne, stockpiling of biosolids has been an option whilst landfilling has not.This has meant financial drivers to reuse are not as strong. Research has been conducted on a range of beneficial uses to suit the different profiles of inputs to biosolids and their regulatory requirements. It is anticipated that this work will be a foundation to increase the beneficial use of biosolids in Victoria in the future”[12].
The third greatest quantity of biosolids, 20895.5 dry tonnes or six per cent of total biosolids production, were used in composted products in the ‘landscaping’ category. These categories also had the same ranking in the 2010 survey. A breakdown of the final management of biosolids on a national level is provided in Figure 3, and Figure 4 illustrates the breakdown of final management by state and territory.
Figure 3 Biosolid end use or treatment by category in 2012–13[13].
Figure 4Biosolids production and use or treatment by jurisdiction and category in dry tonnes in 2012–13[14].
In 2012–13, 69 per cent of total biosolids produced were beneficially used, four per centwere disposed of and 26per cent went to other uses[15]. These figures are not significantly different from those for 2009–10 (see table 2)[16][17].
Table 2Biosolids by aggregated end use or disposal category in 2012–13.
Measurement / Beneficial use[18] / Disposal[19] / Other[20]Dry tonnes (2012–13) / 227914 / 14637 / 86950
Dry tonnes (2009–10) / 198783 / 16597 / 88426
Percentage of total (2012–13) / 69 / 4 / 26
Percentage of total (2009–10) / 65 / 6 / 29
The annual ROU surveys of the organics processing and recycling industry present additional information to understand the beneficial use of biosolids. The surveys are conducted using a survey questionnaire and agreed standard reporting categories that were developed in consultation with state and territory agencies and industry. However, although the survey design was intended to enable consistent reporting, direct comparisons may not be possible between years and between jurisdictions due to variation in survey participation[21] and reporting e.g. reported quantities of biosolids may vary substantially depending on the moisture content (which may be between 20-90 per cent depending on the plant and the weather) and jurisdictions may have diverged from the survey methodology to better suit their own reporting needs.
The only identified category in the ROU survey for biosolids use is “other direct land application (biosolids)”. Table 3 presents the reported amounts of biosolids in kilotonnes from 2005–06 to 2011–12. The ANZBP information reflects a greater diversity of end uses because this information is from the facilities and agencies that manage biosolids at the source, whereas the ROU survey information reflects the processing for end use of biosolids by one industry. The ANZBP figures are lower than the ROU figures for reasons including differences in definitions, survey design, ANZBP reporting on a dry weight basis, while the ROU figures are predominantly reported on a fresh weight basis and include grit and screenings.
Table 3 Reported quantities of biosolids, grit and screenings recovered for beneficial use in land application[22][23].
2005-06 / 2006-07 / 2007-08 / 2008-09 / 2009-10 / 2010-11 / 2011-12PRIMARY PRODUCTION WASTES/BIOMASS (kt)
Biosolids/grit/screenings / 492 / 620 / 626 / 682 / 1150 / 917 / 629
Queensland and NSW both recover relatively high levels of biosolids, grit and screenings (as seen in Table 4) and together represent the major contribution to the total amount of biosolids recovered. This is due to these jurisdictions being both high producers of biosolids and having policy positions which actively support the use of biosolids as a resource. Queensland “promotes higher resource recovery and recycling rates and aims to transform the perception of waste from being seen as ‘waste’ to being valued as a ‘resource’” under the Waste Reduction and Recycling Act 2011 and will provide ‘specific approval’ for the use of biosolids under this Act’s regulations[24]. In NSW, the “government's biosolids management policy is to encourage the beneficial use of biosolids where it is safe and practicable and where it provides the best environmental outcome”[25].
Both Queensland and NSW recorded an overall trend for the increasing reported use of biosolids, grit and screenings in direct land application category, although there was a decrease for NSW in 2008–09 and 2009–10 and then a return to increased use. It was noted that there were variations in the way biosolids, grit and screenings were reported for Queensland in 2009–10, which would have influenced the total amount for all reporting jurisdictions in 2009–10, given Queensland’s contribution[26]. In 2011–12, Queensland reported biosolids, grit and screenings on a dry weight basis which had a major reduction on the reported quantity for Queensland and it is likely that this also had a strong influence on the total amount for 2011–12 i.e. the perceived reduction for the total amount in 2011–12 is likely to be an artefact of the Queensland reporting.
Table 4 Recovery and recycling of biosolids nationally and by jurisdiction in 2010–11[27][28][29]
Material / National / ACT / NSW / NT / Qld / SA / Tas / VIC / WARecovery of biosolids from MSW, C&I and C&D sources (data in thousands of tonnes , rounded to whole number)
- Biosolids (jurisdictional data, WGRRiA)
- Biosolids (ROU) (waste stream source not specified)
Biogas energy recovery from landfill (data expressed as thousands of tonnes of organic material degraded in landfill, rounded to whole number)
- Biosolids (WGGRiA)
Table 4 presents data from two different sources on recovery of biosolids. The WGGRiA figures for 2010–11 are in general higher than the ROU figures. This is assumed to be because the WGRRiA data reflects the whole jurisdiction, while the ROU data reflects the organics reprocessing sector in the jurisdiction. The higher ROU figure for Queensland is an anomaly which may be related to how biosolids were reported in that year i.e. the moisture content.
ROU surveys include the category ‘biofuels/biogas (energy from methane)’ but no data has been recorded against this for 2010–11. WGGRiA reports that the equivalent of 7000 tonnes of biosolids was recovered via biogas energy recovery[30]. NSW biogas recovery from biosolids represents 71 per cent of the national figure and NSW in general recovers relatively high levels of biogas from landfills for energy[31].
Future uses
The use of biosolids as a fertiliser and soil conditioner is likely to continue as there is an established market for these products. However, there are further potential uses for this resource. These include:
- Generating energy
-by anaerobic decomposition of the organic matter which produces methane which can be burnt.
-by direct combustion.
- As a substitute for raw materials such as clay in building products e.g. bricks or as geotechnical fill in construction e.g. for roads.
1
[1]Hyder.Liquid waste assessment(2012)
[2] Australian Water Association (AWA), unpublished material, 2013.
[3]AWA ibid.
[4] Pollution Solutions & Designs for DSEWPaC 2012, Biosolids snapshot.
[5] ANZBP accessed 27 November 2013.
[6] Pollution Solutions & Designs for the Department of the Environment 2012, Biosolids snapshot.
[7]Australian Water Association (AWA), unpublished material, 2013.
[8]Duncan, D, Deighton M, Fleming, V and Smith, C 2009. Final evaluation report on the Smart Water Fund Project ‘Pathogen risk and nutrient status of air-dried and stored biosolids’ unpublished.
[9] The survey covered all sewage treatment plants that serviced a population of over 25,000 people or with a flow rate of fivemegalitres per day. Many water utilities also provided information for smaller plants and this additional information was incorporated in the survey results. AWA, unpublished material, 2013.
[10]Australian & New Zealand Biosolids Partnership (ANZBP) 2013, Biosolids production in Australia: the Australian and New Zealand Biosolids Partnership national survey of biosolids production and end use, Australian Water Association, Sydney.
[11] Australian & New Zealand Biosolids Partnership (ANZBP) 2013, Biosolids production in Australia: the Australian and New Zealand Biosolids Partnership national survey of biosolids production and end use, Australian Water Association, Sydney.
[12]Australian Water Association (AWA), unpublished material, 2013.
[13]AWA ibid.
[14] Australian & New Zealand Biosolids Partnership (ANZBP) 2013, Biosolids production in Australia: the Australian and New Zealand Biosolids Partnership national survey of biosolids production and end use, Australian Water Association, Sydney.
[15] Percentages do not add up to 100% due to rounding
[16]ANZBP 2013 ibid.
[17] ANZBP 2010, Biosolids production in Australia: the Australian and New Zealand Biosolids Partnership national survey of biosolids production and end use, Australian Water Association, Sydney.
[18] Categories include agriculture, forestry, landscaping (compost), land rehabilitation (new in 2013 survey)
[19] Categories include landfill and ocean discharge
[20] Categories include stockpiling, other uses and unspecified uses
[21]Tasmania and the Northern Territory were not included in the survey over this period. In the 2006–7 survey, data for the ACT and Victoria was not available for that financial year and so 2005–6 data was used instead. In 2007–8, Victoria and the ACT did not participate, with the ACT also not participating in the 2009–10, 2010–11 or 2011–12 surveys.
[22]Recycled Organics Unit 2006-2010.Organics Recycling in Australia: Industry Statistics 2006-2010 available at
[23] Recycled Organics Unit for the Department of the Environment 2013 Organics Recycling in Australia: Industry Statistics 2011 and Organics Recycling in Australia: Industry Statistics 2012.
[24] Department of Environment and Heritage Protection (Qld) < accessed 24 September 2013.
[25] Office of Environment and Heritage < accessed 23 September 2013.
[26]Recycled Organics Unit (ROU) 2006-2010.Organics Recycling in Australia: Industry Statistics 2006-2010 available at
[27]Blue Environment and Randell Environmental Consulting 2013.Waste generation and resource recovery in Australia.
[28]ROU 2006-2010 ibid.
[29]ROU for the Department of the Environment 2013.Organics Recycling in Australia: Industry Statistics 2011and Organics Recycling in Australia: Industry Statistics 2012.
[30]To calculate the biogas recovery from landfill, it has been assumed that the annual rate of biogas energy recovery from biosolids is directly related to the annual quantity of biosolids going to landfill. In reality, organics in landfill degrade over decades so the amount of biogas energy recovered in a year can represent many years of decomposition. Biogas production is also influenced by seasonal conditions and landfill management.
[31] Blue Environment and Randell Environmental Consulting 2013 for the Department of the Environment. Waste generation and resource recovery in Australia.