Interlinking legislation creates the steps to allow treated sewage sludge to be used in our environment, harnessing its enriching qualities and reducing waste. It’s a simple win-win for people and planet. But will the EU grasp this opportunity to realise the chain?

With the revision of several key pieces of EU water legislation, the European Commission has a golden opportunity to dispel their inconsistencies so that they can work in harmony, significantly improving the environment.

The Urban Waste Water Treatment Directive (UWWTD), the Industrial Emission Directive (IED) and the Sewage Sludge Directive (SSD) are all undergoing evaluation or revision by the European Commission.

Each of these humble directives has the potential to revolutionise environmental protection and foster circular economy.

At present, these directives work in parallel, almost starting where the other stops, but there are some glaring gaps and inconsistencies.

Three trains, a three-pronged track

These three directives drive how pollutants are treated as they come into contact with our waste water. The Commission has the opportunity to ensure they synchronise them so we can maximise their potential.

The Industrial Emissions Directive is the main EU instrument regulating pollutant emissions from industrial installations. Industrial production processes account for a considerable share of the overall pollution in Europe due to their emission of air pollutants, discharges of waste water and the generation of waste.

“with the revision of several key pieces of EU water legislation, the European Commission can dispel their inconsistencies”

The IED aims to achieve a high level of protection of human health and the environment by reducing harmful industrial emissions, in particular through the better application of Best Available Techniques (BAT). Around 50,000 installations undertaking industrial activities are required to operate in accordance with a permit (granted by Member State authorities). This permit should include the conditions for discharging waste water set under the principles and provisions of the IED.

Sewage Sludge

Depending on national legislation and agreements between the industrial installation and the local Urban Waste Water Treatment Plant (UWWTP) operator, if this discharged waste water enters the sewer system then it comes under the auspices of the Urban Waste Water Treatment Directive (UWWTD). This legislation aims to protect the environment from the adverse effects of urban waste water discharges and discharges from certain industrial sectors by mandating waste water collection and treatment in urban areas with a p.e. (population equivalent) of over 2,000.

The water received by UWWTP contains everything from solid materials to micro- and nano- particles, including industrial chemical components. Treating the waste water so that it can be safely returned to the environment is costly and as there is not one treatment process to remove all pollutants, it can take several processes to ensure the water meets environmental standards.

“pre-treating water before it arrives at the UWWTP, protects against toxic exposure, and provides a better quality of sludge to be reused”

The EU should grasp this opportunity to require an agreement between industry and municipalities to determine the necessary level of pre-treatment before industrial water is released into the municipal sewer system.

As only 50,000 industrial installations are covered by the IED today and it’s not necessarily effective to cover small and medium enterprises, we ask for the UWWTD to include a provision for the treatment of effluent before it reaches the WWTP to protect workers, treatment processes and sludge quality. This could be included in the permit issued in coordination with the municipality. 

There are many benefits. For starters, consumers would not have to foot the bill for these (sometimes) costly treatments, as the responsible producer would pay for the treatment. It would also avoid the accumulation of pollutants in the WWTP sewage sludge. It also has health and safety impacts. By pre-treating water before it arrives at the UWWTP, both workers and the biological treatment of the UWWTP are protected from toxic exposure. Doing this will give us a better quality of sludge to be reused.

Sludge is the result of the biological and chemical treatment of the waste water entering the UWWTP. Therefore, it contains valuable organic matter and nutrients such as nitrogen and phosphorus, and can be very useful as a fertiliser or soil improver in agriculture. However, it can also contain heavy metals and other pollutants, if control at source measures are not efficient enough to remove these further up the chain. The use of sludge in agriculture is regulated by the Sewage Sludge Directive (SSD) in order to protect the soils from pollution.

So far, so good. Each of the directives is working as it should. However, this is where the trains begin to diverge. Different directives apply to sludge, depending on where it is in the process.

The UWWTD is the principal instrument responsible for the generation and collection of sewage sludge.

The processing of sludge, its treatment and recovery are governed by two main European directives: the IED and the Waste Framework Directive1. The SSD has some provisions on processing but it concerns only sludge used in agriculture.

Sludge management practices vary across the EU and this is reflected in the varied application of the IED to sludge. Additionally, this directive covers the anaerobic digestion of waste as a regulated activity but includes a rather ambiguous statement that it does not apply where the activity is covered by UWWTD. This leaves much to the interpretation by the individual Member State or region.

The UWWTD plays a role in the processing of sludge but this directive does not provide any details of how it should be done. However, where all processing is handled within the confines of a WWTP, the IED does not apply; so in some instances, there is no requirement to process sludge as the UWWTD does not give any requirement on its principle by-product and on the other hand, the IED does not apply to all facilities.

The Commission must work to make these directives coherent so that they can effectively work together to protect people and the environment. We believe that the Commission should regroup requirements on sludge management in the UWWTD. Some specific treatments should remain under the IED like incineration or in very large installations but as long as municipal sewage sludge is treated, whether it is from one or more UWWTP, it should be covered by the UWWTD.

If the Commission achieves this, the rewards will benefit everyone.

“it is crucial that the wider EU-level legislative framework supports and demands effective source control measures and limits the use of harmful substances”

What goes in can’t always come out

Micropollutants can directly or indirectly enter the water cycle through many means. Once in the water cycle, they can pose a risk to the water environment, ecosystems and human health and to the possibilities of a circular economy.

Sewage Sludge

At EurEau, we have consistently advocated for a control at source approach to micropollutants as well as for the implementation of the Precautionary Principle in environmental policy as the most sustainable way to protect water resources.

In fact, EU legislation is built on the Precautionary, Control at Source and on the Polluter Pays Principles.

The quality of sludge produced in our UWWTP is a product of the society which generates it. The number of contaminants ending up in the sludge can be influenced by working systematically with control at source in various ways. It makes sense to prevent these from entering UWWTP in the first place, through effective IED legislation for the largest installations. New provisions are needed in the UWWTD to cover more small and medium plants and through increased control of the effect of consumer products on waste water quality through the life cycle of products from design to end of life.

Apart from the various measures water utilities are able to carry out, it is crucial that the wider EU-level legislative framework supports and demands effective source control measures and limits the use of harmful substances.

Stringent requirements for the authorisation of substances under the REACH Regulation, based on their intrinsic properties, are crucial to avoid harmful substances entering the water cycle. Secondly, adequate pre-treatment of industrial effluents is essential. The main responsibility lies with the industry but a clear regulative framework and practises between industry, authorities and water utilities are necessary to implement this.

Why this emphasis?

‘Biosolids’ are the result of the refining processes of sewage sludge in order to apply it on land. Several processes can be used to achieve the required quality. For agricultural use, the main objective is to have biosolids which improve soil quality, have carbon and nutrient value, are stable and easy to transport and convenient to spread on fields, locking also carbon in the ground instead of the air.

Organic matter and carbon are of vital importance to European soils. Some 45% of soils in Europe have a low or very low organic matter content. This is particularly evident in many southern European countries, but it is also the case in some other countries2. Carbon is also needed to enable soils to be resilient to more frequent and intense droughts or rainfall events. Sewage sludge has a role to play in the transition to sustainable agriculture, where fields are harnessed as carbon sinks.

Many decades of implementing certification systems in different countries have constantly improved how to sustainably produce good quality organic fertilisers that comply with high quality standards.

Local conditions and practices define which method will be the most applicable to produce biosolids. Co-treatment of various raw materials either in co-digestion or co-composting units is usually the most technically and economically feasible solution. Regional units commonly collect organic materials and process organic waste from industries and municipalities together with sewage sludge.

At the moment biosolids are widely used in agriculture and landscaping. However, it still has unexplored potential, such as in forestry.

Recently new technologies have emerged to produce new products from sewage sludge like bioplastics, biogas, biofuel, struvite and even recovered products from ashes although these are not yet pulled by the fertiliser market. Incineration is generally combined with energy recovery.

The future is a circle

Sewage Sludge

Currently, the choice of sludge management for UWWTP operators depends on multiple factors: the quality of the sludge, the control at source measures used, the market and interest of farmers for the use of biosolids in agriculture, the existing capacity for incineration, the costs associated with sludge management etc. However, certain solutions are increasingly under pressure and some so-called solutions like landfill should be phased out. In order to be able to continue collecting and treating waste water for the health of humans and the environment, it is vital that waste water operators consider strategies/drivers to maintain different solutions available for the resilience of the future management of sludge.

The circular economy should be an important driver for future development, but the Commission only mentioned sludge in the New Circular economy Action Plan (NCEAP) in that the SSD should be evaluated. However, the necessary paradigm shift to enter into a real circular economy has to be planned for investments and management options according to the circular objective. The enabling regulatory framework needs to be developed to support the NCEAP3.

Despite the fact that the NCEAP only briefly mentioned sludge, we have the opportunity to develop an enabling regulatory framework through the evaluation of the Sewage Sludge Directive and the revision of the UWWTD and IED.

Recovery and reuse of nutrients (Integrated Nutrient Management Plan) and materials from waste water treatment is already taking place, and new solutions are being developed. Innovative business models for recovered materials, legislation that promotes recovered material from the water industry, and a level playing field are needed to improve cost-effectiveness, without adding unnecessary administrative burdens on water services (creating a well-functioning EU market for secondary raw materials).

To allow the circular economy to fully develop, the legislative framework needs to support a change of mind-set of operators, to move from managing sludge to taking actions to produce secondary resources. To achieve this, operators need to be supported by both a strong chemical authorisation process and adjustable discharge permits to control the release of substances into sewers that could threaten the circularity of the sewage sludge. In that sense the zero pollution ambition4 of the European Commission should really look at the downstream consequences for the circularity of the sewage sludge of putting products and substances on the market. And finally the movement (transport) of the secondary raw material needs to be facilitated across Europe within the single market.

The European Green Deal should foster the development of solutions, accompanied with the financial tool to secure investment that will allow to close the cycle for nutrients.

Right now, these three directives work like clockwork that is missing a few spokes from their cogs; they generally tick along but there are gaps that lead to missed opportunities. In short, valuable waste shouldn’t – and isn’t – be something to be discarded or forgotten about. A control at source approach in the IED for industrial discharge will help avoid this. The European Commission can rectify this in the coming months with the planned revisions. We have an opportunity to help make our economies circular and reduce our waste. It is an opportunity not to be missed.

EurEau will work with the EU to ensure the forthcoming legislation is fit for purpose.