Abstract: High levels of polyhydroxyalkanoates (PHA) can be produced from wastewater comprising Readily Biodegradable COD (RBCOD) using activated sludge comprising microorganisms capable of accumulating PHA by contacting the wastewater with the activated sludge in the presence of dissolved oxygen during a first period of time, to obtain PHA-loaded activated sludge, and then supplying elements essential for growth such as nitrogen and phosphorus and allowing up-take of these elements and limited growth during a second period of time, the supplied amount of at least of one of said essential elements compared to the amount of RBCOD supplied in step a) limiting the growth to an extent that not all PHA is used for growth, to obtain grown activated sludge; and removing or harvesting part of the PHA-loaded activated sludge and/or part of the grown activated sludge, so that the total average retention time of the sludge is less than 72 h.

Abstract: Wastewater containing a significant level of dissolved readily biodegradable organic compounds matter, such as short-chain fatty acids, and ammonia can be efficiently treated to remove most or all of the organic compounds and the ammonia, with the production of microbial storage compounds such as polyhydroxylkanoates, by (i) subjecting the wastewater storage compound-accumulating microorganisms (SCAM) in the presence of oxygen, (ii) subjecting at least part of the resulting partly treated wastewater to ammonia-oxidising microorganisms (AOM) in the presence of oxygen and (iii) feeding a gas containing molecular carbon dioxide produced during step (ii) to step (i) so as to lower the pH in step (i).

Abstract: Wastewater containing a significant level of dissolved readily biodegradable organic compounds matter, such as short-chain fatty acids, and ammonia can be efficiently treated to remove most or all of the organic compounds and the ammonia, with the production of microbial storage compounds such as polyhydroxylkanoates, by (i) subjecting the wastewater storage compound-accumulating microorganisms (SCAM) in the presence of oxygen, (ii) subjecting at least part of the resulting partly treated wastewater to ammonia-oxidising microorganisms (AOM) in the presence of oxygen and (iii) feeding a gas containing molecular carbon dioxide produced during step (ii) to step (i) so as to lower the pH in step (i).

Abstract: High levels of polyhydroxyalkanoates (PHA) can be produced from wastewater comprising Readily Biodegradable COD (RBCOD) using activated sludge comprising microorganisms capable of accumulating PHA by contacting the wastewater with the activated sludge in the presence of dissolved oxygen during a first period of time, to obtain PHA-loaded activated sludge, and then supplying elements essential for growth such as nitrogen and phosphorus and allowing up-take of these elements and limited growth during a second period of time, the supplied amount of at least of one of said essential elements compared to the amount of RBCOD supplied in step a) limiting the growth to an extent that not all PHA is used for growth, to obtain grown activated sludge; and removing or harvesting part of the PHA-loaded activated sludge and/or part of the grown activated sludge, so that the total average retention time of the sludge is less than 72 h.

Abstract: The invention relates to a process for producing a microbial storage compound, in particular polyhydroxyalkanoate, using micro-organisms capable of accumulating such microbial storage compound, wherein such micro-organisms are selected and the microbial storage compound is accumulated by carrying out the so-called feast phase of the selection step and the accumulation of the microbial storage compound in selected micro-organisms in the same reactor and carrying out the so-called famine phase of the selection step in a separate, smaller, reactor.

Abstract: A process for removing sulphide from an aqueous solution comprising sulphide is disclosed, in which the aqueous solution is subjected to sulphide-oxidizing bacteria in the presence of oxygen in a reactor to oxidize sulphide to elemental sulphur. According to the process, a molecular-oxygen containing gas is supplied to a reactor containing the sulphide-oxidizing bacteria in an aqueous medium, such that one or more aerated zones and one or more non-aerated zones are created in the aqueous medium with upward liquid flow in the aerated zones and downward liquid flow in the non-aerated zones; and a feed stream of the aqueous solution comprising sulphide is injected into the reactor in the one or more non-aerated zones, wherein the one or more aerated zone(s) are not separated from the one or more non-aerated zone(s) by means of vertically extending reactor internal.

Abstract: The invention relates to a process for producing a microbial storage compound, in particular polyhydroxyalkanoate, using micro-organisms capable of accumulating such microbial storage compound,wherein such micro-organisms are selected and the microbial storage compound is accumulated by carrying out the so-called feast phase of the selection step and the accumulation of the microbial storage compound in selected micro-organisms in the same reactor and carrying out the so-called famine phase of the selection step in a separate, smaller, reactor.

Abstract: A process for removing sulphide from an aqueous solution comprising sulphide is disclosed, in which the aqueous solution is subjected to sulphide-oxidising bacteria in the presence of oxygen in a reactor to oxidise sulphide to elemental sulphur. According to the process, a molecular-oxygen containing gas is supplied to a reactor containing the sulphide-oxidising bacteria in an aqueous medium, such that one or more aerated zones and one or more non-aerated zones are created in the aqueous medium with upward liquid flow in the aerated zones and downward liquid flow in the non-aerated zones; and a feed stream of the aqueous solution comprising sulphide is injected into the reactor in the one or more non-aerated zones, wherein the one or more aerated zone(s) are not separated from the one or more non-aerated zone(s) by means of vertically extending reactor internal.

Abstract: Methane can be used as a source for producing hydrogen or hydrogen equivalents in a biological process using mesophilic or thermophilic bacteria of the order of the Thermotogales, e.g. Thermotoga maritima. Hydrogen can be produced as such, or as a reducing equivalent for the reduction of various compounds such as sulphur compounds. Especially, the methane oxidation can be used for anaerobically reducing sulphate to sulphide using methane as the predominant or sole electron donor, in coculture with sulphate-reducing micro-organisms.

Abstract: A process for the treatment of waste water containing heavy metals in which sulphur components and/or metals are biologically reduced to precipitate the metals as water-insoluble metal species, which are separated from the waste water. The biological reduction and the precipitation of the metal species are carried out in a moving sand bed, in which sand particles partly immobilize the bacteria and retain the precipitated metal species, treated waste water is separated from the precipitated metal species and the precipitated metal species are subsequently separated from the sand particles. Metals like selenium and uranium can be precipitated without sulphur components, whereas metals like antimony, cadmium, copper, zinc and the like are precipitated as sulphides.

Abstract: A process is described for the biological treatment of waste water containing ammonia, wherein the waste water is treated with sludge containing nitrifying bacteria in an aerated reactor, applying a sludge retention time in the reactor which favours nitrite-producing bacteria over nitrate-producing bacteria. The process is characterised by applying a hydraulic retention time in a continuously operated reactor, which is shorter than the sludge retention time as a result of part of the sludge being separated from the reactor effluent and being returned to the reactor. The performance of the nitrification is further improved by applying low oxygen and nitrite concentrations.

Abstract: A device for purifying flue gas containing nitrogen oxides, in which the flue gas is scrubbed with a circulating scrubbing liquid which contains a transition metal chelate such as Fe(II) EDTA and the complex formed from nitrogen oxide and transition metal chelate and/or spent transition metal chelate is regenerated biologically in the presence of an electron donor, nitrogen oxide being reduced to molecular nitrogen. The biological reactor can be combined with the gas scrubber. The electron donor is, for example, hydrogen or methanol, but may also be sulphite which originates from sulphur dioxide in the flue gas.

Abstract: A process and a device for purifying flue gas containing nitrogen oxides, in which the flue gas is scrubbed with a circulating scrubbing liquid which contains a transition metal chelate such as Fe (II) EDTA and the complex formed from nitrogen oxide and transition metal chelate and/or spent transition metal chelate is regenerated biologically in the presence of an electron donor, nitrogen oxide being reduced to molecular nitrogen. The biological reactor can be combined with the gas scrubber. The electron donor is, for example, hydrogen or methanol, but may also be sulphite which originates from sulphur dioxide in the flue gas.