Since the development of the UASB process in the 1970s this process has been widely applied for the treatment of industrial effluents. Effluents from alcohol producing industries are mostly highly polluted and therefore in principle very suitable for anaerobic treatment. Distilleries use different kinds of raw materials such as sugar cane juice, sugar cane molasses, sugar beet molasses, wine or corn for the production of alcohol. The use of different materials and the different processes applied, result in a wide variety of effluents produced. The process conditions under which good results of the anaerobic process are obtained depend heavily on the type of distillery effluent being treated. The choice of the right set of process parameters for every type of distillery effluent has shown to be of crucial importance for the anaerobic process. Experience of anaerobic treatment on effluents from different alcohol-producing industries over a long term period are discussed. Special attention is given to the treatment of effluents from sugar cane based distilleries with very high COD concentration of 60 000 to 160 000 mg COD 1−1. Despite expected toxicity problems arising from the high concentrations of COD, sulfide and salts, anaerobic treatment with the UASB process proved to be successful in treating distillery effluent.

Internal Circulation (IC) reactors can be operated at higher reactor volume loading rates than Upflow Anaerobic Sludge Blanket (UASB) reactors. This results in increased gas production rates and subsequently higher average shear rates in IC-reactors. Furthermore, the liquid upflow velocity is 8-20 times higher, still granules develop successfully in IC-reactors. To investigate the granule development in IC-reactors and elucidate the process limitations with respect to granule development and biomass retention, granule samples from three full scale IC-reactors are characterized. Characterization included size distribution, strength, settling velocity, density, ash content and methanogenic activity. Granules were compared with samples from UASB reactors treating similar types of wastewaters. A hydrodynamic model was developed to describe the liquid circulation in IC reactors. The average shear rate in IC reactors is approximately twice as high compared to UASB-reactors. The two stage design of the IC-reactor allows 3-6 times higher loading rate. The experimental results showed that IC-granules are larger than UASB-granules grown on similar wastewater, while the strength of IC-granules is lower as a result of the higher sludge loading rate. Although wash-out is slightly enhanced in IC-reactors, the conditions in the second stage are tranquil enough to ensure adequate biomass retention in IC-reactors. The development of characteristic IC-granules after seeding proceeds within a few months. Physical characteristics of granules are determined mainly by biological factors.

The paper discusses conversion capacities of both anaerobic and aerobic wastewater treatment systems in relation to growth kinetics, hydrodynamics and biomass concentration. In the current modern anaerobic high-rate reactors the conversion potentials are optimally exploited. This is not yet true for aerobic systems since operation of aerobic systems under conditions of low biomass growth reduces the maximum applicable loading rates significantly. Both the concept of granulation and the introduction of fluidised bed systems have increased conversion capacities for both anaerobic and aerobic systems significantly. One of the latest development concerns the SBR with granular biomass. The grazing concept, in which ciliates convert aerobically grown dispersed cells, offers a possibility for significant improvement of aerobic systems. In the fields of psychrophilic and thermophilic anaerobic treatment, specific reactor development may contribute to further enhance volumetric conversion capacities. Due to reduced water usage, both COD and salt concentrations tend to increase for industrial effluents. As a consequence, there is a need for the development of anaerobic reactors retaining flocculant biomass. The membrane bioreactors offer a solution for certain niches in wastewater treatment. However the oxygen transfer economy is poor. There is a need for fundamental knowledge development to obtain a realistic image of this technology.

Despite an improvement of water quality across Europe there are many pollution hotspots for both nitrates and PPPs, mainly due to agricultural activities. The BMPs and MMs to reduce pollution from agriculture are well known, and there are policy instruments in place to ensure drinking water standards, but the current approach has not been efficient enough. Within the H2020 Water Protect project the premise was that there is a need for a multi-actor, participatory approach to tackle the issue from a new angle, and to assess why the uptake of known BMPs and MMs was not better among farmers. Seven “Action Labs” were selected that represent major physical, socio-economical, cultural and farming settings across Europe. A methodology of multi-actor engagement was chosen but with different approaches due to the local context. Initially the level of farmers' awareness about water quality issues was matched to the observed uptake rates of BMPs and MMs. In a second survey barriers hindering the uptake of measures were identified. The first survey revealed a low general awareness on the potential pollution to drinking water sources. Despite this, between 24% to 88% of the surveyed farmers per Action Lab were already voluntarily adopting one quarter of the selected BMPs and MMs. The second survey demonstrated the need to address organisational, legislative, sociological and technical barriers. The lack of coordination between different institutional bodies promoting measures and the financial incentives needed to invest and operate these often-costly measures need to be considered. The multi-actor, participatory approach with its improved awareness and collaboration made it possible to identify the crucial factors for improvement - to build a social acceptance among all actors and communicate the issues and solutions from the start.

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