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Barriers to Recycling of Sludge

Summary and conclusions

In 2003 the recycling of sludge will require that about 3% of Danish farmland is manured with sludge. This report addresses the factors presenting barriers to the recycling. Barriers were found by interviewing stakeholders.

The aim of this project is to give counties and other sludge producers a basis to rank and focus their efforts to recycle sludge. Crop farmers without livestock production have a product, which so far they have not tried to sell to the sludge producers. This project is therefore useful to farmers as well as their associates.

The three most important obstacles facing each of the participants interviewed are treated below.

The three most important barriers for the participants, listed in random order:

All participants mention competition from other products as important barriers. These include competition from livestock farming, mainly pig farming, and from industrial waste products, mainly Novogro 30. Competition reduces sales opportunities for sludge producers as agriculture has several types of free manure to choose from.

All participants see certainty of sales as a potential obstacle. The sludge must be removed to enable the treatment plant to function. Citizens and industry depend on the discharge and treatment of wastewater. Agriculture focuses on the certainty of marketing the agricultural products and on the sale of farmland.

The certainty of sales is more important for all participants than a short-term improved financial result. This argument is one of the reasons for the considerable difference in prices for wastewater treatment, since it is often twice as expensive to burn the sludge than it is to recycle it on farmland.

The quality of the sludge presents a direct or indirect barrier to all participants.

The sludge producers must comply with quality requirements in the form of limit values. The quality of sludge is continually improving as organic micro pollutants and metals are used less and less. Today the content of cadmium in sludge is approximately the same as in fertilisers. Approximately 65% of the total amount of sludge can be recycled.

Earning potential is important to the farmers. The financial advantage of: savings when buying smaller amounts of fertiliser; getting value from the lime in sludge; having spreading paid for, and receiving payment for sludge must be compared with the income achieved from crop sales. The total financial result must be advantageous.

The sludge users want to be sure that the contents of the sludge make it possible for them to preserve their production and sale in the future. Non-users and agricultural advisers express uncertainty as to the quality of sludge with regard to possible xenobiotic substances which are not measured.

Non-users are often livestock farmers and have no areas available for sludge. At the same time they constitute an important competitor to the sludge producers, as they often have more liquid manure than they can use on their own land, and naturally they want to sell the liquid manure to crop farmers. Many non-users find that sludge is a problem for society to solve, not agriculture. Most non-users think that sludge should not be used on farmland.

Crop farming advisers believe that crop farmers should carry a minimal risk when using sludge. They want certainty / guarantee that there will be no future problems.

The report proposes different activities that may stabilise the sale and marketing of sludge reuse on farmland. It is important to realise that supply and demand of farmland and fertilisers are vital factors. The demand is higher for farmland than for fertiliser. The land itself gives the farmer right to carry out livestock farming which provides larger earning per ha - earnings the farmer will have to give up when receiving sludge. Therefore, the sludge producer must pay the crop farmer for using his land as an outlet channel.

Manure is produced in excess in Denmark, and therefore the price of manure is zero. Although they are not paid for the sludge, it is cheaper for sludge producers and their customers to give the sludge away for free for use as fertiliser than to burn it. For society it is an advantage that the sludge is recycled because it is cheaper and saves money for other purposes. Furthermore, the recycling of sludge is an important factor in the continuous effort against chemicals - an effort which does not allow for the use of unwanted chemicals which will contaminate the sludge and make it unfit for recycling. Furthermore, the national load of fertilisers, which may cause eutrophication, will be reduced.

In 1995 the Danish Parliament passed a recommendation on the use of wastewater sludge on farmland: It says:

“The Minister for the Environment and Energy gives the assurance that no farmer who uses wastewater sludge as manure as laid down in the instructions will in future be met with demands on the quality of the farmland as cultivated area, and which is of such a kind that they will prevent the farmer from using the land to grow all agricultural crops owing to his previous use of wastewater sludge.”

This is a kind of guarantee, however without stating the word guarantee. As follow-up to the recommendation, the Danish Parliament has earmarked a sum to investigate the sustainability of sludge. In an extensive study, the Danish Institute of Agricultural Science has concluded that the risk of using sludge is minimal when the sludge is used according to Danish legislation on the subject.

There is a need for a dialogue between crop farmers and owners of wastewater treatment plant with the aim of obtaining advantages for both parties by recycling the sludge.

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Version 1.0 Juni 2004, © Miljøstyrelsen.