| 摘要 |
<p>The invention provides methods for reducing the oxyanion (e.g. nitrate) content of an aqueous solution, for example drinking water. Such methods involve the use of at least one, preferably two, membrane bioreactors (MBRs) operated downstream of a conventional ion exchanger. Where two MBRs are employed, these are operated in series. In the methods described, spent brine produced following the regeneration of an exhausted ion exchange resin is treated in a first MBR operated under anoxic conditions to produce an effluent which has a low oxyanion (e.g. nitrate) content and which can either be disposed of or, more preferably, re-used in the ion exchange process as a regenerant for the ion exchange resin beds. In a further aspect, a second MBR which is operated under aerobic conditions is employed to treat the waste sludge from the first anoxic MBR. The effluent from this second MBR may also be recycled for use as a regenerant in the ion exchange process. The overall result is an essentially 'zero waste' process which is especially suitable for the treatment of drinking water.</p> |
