Biological treatment

There is a worldwide increase in demand for facilities that derive energy from organic waste material. WTT specializes in various technologies like anaerobic digestion, refuse derived fuel (RDF) and biomass treatment.

Product overview

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Biological techniques

Anaerobic digestion

Anaerobic digestion (AD) is an economically and politically preferred treatment method for organic waste streams. WTT can supply two different AD systems to be able to find the optimal solution for each specific situation. These are the Dry AD batch process, where waste is digested in large concrete boxes, and Wet AD systems, where the Pulper System and the Press System are pretreatment options.

Composting and biodrying

WTT’s biological tunnel process is individually controlled in order to provide each batch with a tailor-made treatment. WTT’s fully automated process allows the operator to set process parameters to adapt different waste categories and seasonal influences. Its modular construction and versatile control software interface allows the same facility to treat organic waste optimally in short a period of time, maximizing processing efficiency and keeping environmental conditions strictly under control.

Odour reduction systems

WTT has developed a wide range of odour-reduction systems, including bio filtration and air humidification technology. Our wide experience and practical knowledge of these systems has provided the know-how to guarantee low-level odour output in any installation.

Types of waste

(MSW) municipal solid wasteicon_municipal

In many countries landfill extension is difficult or impossible. For these circumstances, WTT designed a MSW separation-system with high-tech processes, which will split-up the MSW in reusable and non-useable streams.

The reusables are local market depending, but mostly iron, aluminium, paper, cardboard, PVC, PET, textiles and more. All of these materials are completely prepared for delivery to the reprocessor.

The rest fraction will be intensively biological treated and its mass and biological activity reduced significantly.This solution provides a system upfront the landfill by 50 – 75%. The equipment can also be configured to separate semi-usable-compost for landfill cover and meet your recycling targets.

Source separate organic wasteicon_organicwaste

These are the well known composting plants, which started back in the 1980’s when the Netherlands and Germany introduced multi bin source separation schemes for the capture of all kinds of different waste produced in homes.

For the first time, householders were legally required to separate the organic waste (mostly kitchen and garden waste) into a separate (green) bin. This waste was collected and composted in various styles including flat-heap systems, drum-system containers and tunnel systems. The tunnel-system was the most efficient and operator friendly design and consequently is now the most common system. WTT developed and improved the tunnel-system into the most efficient and compost can be produced within this system of “Rottegrad” IV-V within 4 weeks time.

The WTT-staff were involved in the first biowaste-tunnel-composting-installation in 1994 and have subsequently build over 900 tunnels. Throughout this time WTT has continously improved the design and identified methods of reducing the capital and operating costs.


In Northern-Europe waste water targets were set in the 1970’s to implement a 0% target for uncleaned waste water disposal. This means that all waste water needed to be treated via a (biological) water cleaning installation. These installations were build and the targets were met, however, one of the sub-products (waste) produced was sludge. This sludge’s became more and more of a problem as significant amounts required landfilling.

For this reason alternative solutions to landfill were investigated. Several options like incineration, agriculture use, drying and composting were investigated. WTT developed composting systems which handle sludge and could significantly reduce its weight and turn it into compost.

The main difficulties with the treatment of the sludges were the challenges of sufficiently aerating the material and also how to use biofiltration with the high ammonia content in the output air. WTT did solve these problems within its tunnel-composting-process and the latest design is able to transform sludge with 20% solid content into compost with 60-80% solid content within 10 – 14 days.

The reduction in total mass will go as high as 5 times (to 20%). The sludges can be composted as long as there is sufficient degradable organic content in the dry matter. WTT sludge-composting-system produces for compost agriculture (wine grapes production) use.

Garden and biowasteicon_biowaste

As previously mentioned, in Northern-Europe waste was being separated at homes and by down stream mechanical treatment systems.

Commercial green and ‘yard’ waste produced by highway-sides, park cuttings etc. was normally compost out-side using windrow-systems. As population density increases, the availability of potential development sites decrease and the requirement for relatively low odour production is given.

Therefore WTT developed an aeration system for the windrows, which introduced oxygen in a special way (injection), so that anaerobic spots are significantly reduced.

In general, this results in significant odour reduction, especially during the turning of material. WTT has implemented this system throughout Holland and now it is an obligation for any new facility.

Animal manureicon_manure

A typical Dutch problem, due to the large population and still many agricultural activities, is manure over-production.

In Holland, the amount of manure that can be spread on land is very limited. This has created a demand for preparation facilities to solve this problem.

WTT has developed a composting system which reduces the manure using its own biological activity to stabilise the material and reduce the weight and moisture content.

The product can be sold in dried manure.