ÐBiological treatment of a piggery wastewater for organic carbon and nitrogen removal in a combined anaerobic±aerobic system was investigated using two laboratory-scale sequencing batch reactors. The cycle length was 24 h. In the anaerobic reactor, fed with raw wastewater and recycling from the aerobic reactor, denitri®cation followed by anaerobic digestion of organic carbon was observed. In th...

BACKGROUND Secretion of heterologous proteins depends both on biomass concentration and on the specific product secretion rate, which in turn is not constant at varying specific growth rates. As fed batch processes usually do not maintain a steady state throughout the feed phase, it is not trivial to model and optimize such a process by mathematical means. RESULTS We have developed a model fo...

D-lactic acid was produced by Sporolactobacillus sp. strain CASD in repeated batch fermentation with one- and two-reactor systems. The strain showed relatively high energy consumption in its growth-related metabolism in comparison with other lactic acid producers. When the fermentation was repeated with 10% (v/v) of previous culture to start a new batch, D-lactic acid production shifted from be...

An economical bioreactor designed for evaluating the biogas potential of particulate biomass is described. The bioreactor uses a simple stirring apparatus, called the Bordeaux stirrer, to enable gas-tight mixing of fermentation cultures. The apparatus consists of a low-rpm motor connected to a bent steel stir rod, which is placed in a length of flexible plastic tubing inserted through a rubber ...

The cybernetic framework developed by Ramkrishna and co-workers has been expanded to include the effects of cellular maintenance energy requirements on biomass levels in slow-growing, carbon-substrate-limited cultures. A simple structured model, based on the existence of distinct key enzymes for growth and maintenance functions, is presented. Comparisons of the model with experimental data for ...

Recombinant alkaline polygalacturonate lyase (PGL) production by recombinant Pichia pastoris GS115 was selected as a model to study as a continuous culture strategy for enhancing heterologous protein production based on controlling methanol feeding (CCCM culture) or on dual carbon source feeding (CCCD culture). Using the CCCM process with a dry cell weight of 75 g/L regulated by controlling met...

In the fine chemical industry the batch or fed-batch reactor functions as the heart of the transformation process. Due to the complexity of chemical synthesis, the control of these reactors remains a problem of temperature control commonly performed indirectly via the jacket of the reactor. This results in a cascade control scheme based on the control a secondary, more responsive process that i...

Anaerobic oxidation of methane coupled to sulphate reduction (SR-AOM) prevents oceanic methane emissions and is considered as a major environmental process in the deep-sea sediments. To stimulate in vitro SR-AOM activity, we designed a (continuous) high-pressure bioreactor system. Fed-batch mode incubations showed that the elevated methane pressure stimulated SR-AOM activity: when the methane p...