Evaluating the effects of scaling up on the performance of bioelectrochemical systems using a technical scale microbial electrolysis cell.

This study focuses on the challenges of the scaling up process of bioelectrochemical systems on the example of a technical scale microbial electrolysis cell referred to as the "prototype". Anodically treating real wastewater and operated in continuous mode at a hydraulic retention time of 1.23 d with an average chemical oxygen demand (COD)-loading rate of 0.5 g O2 d(-1) L Reactor(-1) the prototype on average showed COD removal efficiency of 67% with effluent concentrations of 210 mg O2 L(-1) and an ammonium elimination rate of 17.8 ± 3.9 mg Nd(-1) L Reactor(-1) resulting in effluent concentrations of 30.7 ± 3.7 mg NL(-1) with a removal efficiency of 40% at a current generation of 72 µA cm(-2) and Coulomb efficiency of 11%. A model is described as a method for comparing conventional and BES based technology using the above mentioned criteria and balancing them against the respective loading rates.

Sludge treatment and reuse considering different climates and varying other conditions--export-oriented research for developing and threshold countries.

Sewage sludge accumulating during biological wastewater treatment has to be treated appropriately to avoid impacts on the environment and risks to public health. Especially pathogen reduction is necessary when sludge is disposed or reused in such a way that human contact is possible. In industrialized countries various sludge treatment technologies are available, but these are often only approved under local conditions. When exporting these technologies and experiences to other countries, a number of factors have to be taken into account including climatic, sociocultural, political and financial aspects. This paper gives an overview of current knowledge regarding sewage sludge treatment in developing countries. Various sanitation projects are realized worldwide and experiences from these plants already in operation are summarized. Results of on going laboratory experiments in climatic chambers regarding aerobic and anaerobic stabilization as well as lime treatment are shown to define the best-practicable sludge treatment technology for a certain climate. Options for final reuse or disposal are presented depending on end-product quality.

Operating problems in anaerobic digestion plants resulting from nitrogen in MSW.

Organic waste and municipal solid waste usually contain considerable amounts of different nitrogen compounds, which may inhibit anaerobic degradation processes and cause problems in the downstream and peripheral devices. This refers particularly to the different process stages of anaerobic digestion, to wastewater treatment, and to exhaust air treatment. Neither the knowledge about nitrogen problems nor the technologies for elimination of nitrogen compounds from the wastewater or the exhaust air of anaerobic digestion can be regarded as state-of-the-art. Most of the technologies in question have already been applied in other areas, but are barely tested for application in anaerobic digestion plants. The few performance data and experiences at hand were mainly derived from pilot and demonstration facilities. In this paper, the problem of nitrogen will be discussed in detail according to the separate problem fields based on the authors' experience, as well as on the basis of a review of the relevant literature. Furthermore, possible solutions will be proposed and the need for further research and development will be formulated.