污水处理-英文文献4

Desalination 231 (2008) 20–260011-9164/08/$– See front matter © 2008 Elsevier B.V

. All rights reserved

at The 4th IWA Conference on Membranes for Water and Wastewater Treatment

May 15–17, 2007, Harrogate, UK

*Corresponding author.

Upgrading and retrofitting of municipal wastewater treatment

plants by means of membrane bioreactor (MBR) technology

Ch. Brepols a , E. Dorgeloh b , F.-B. Frechen c , W. Fuchs d , S. Haider e , A. Joss f ,K. de Korte g , Ch. Ruiken g , W. Schier c *, H. van der Roest h , M. Wett i , Th. Wozniak j

a

Erftverband, Bergheim, Germany

b

Prüf- und Entwicklungsinstitut für Abwassertechnik (PIA) an der RWTH Aachen, Germany c

Department of Sanitary and Environmental Engineering - DESEE, University of Kassel, Germany Tel. +49 (561) 8043817; Fax +49 (561) 8043642; email: wernfried.schier@uni-kassel.de d

University of Natural Resources and Applied Life Sciences – Vienna, Department IF A-Tulln,

Institute for Environmental Biotechnology, Tulln, Austria

e

H2Office Abwassertechnik, Wien, Austria

f

EAWAG — Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland

g

DWR — Dienst Waterbeheer en Riolering, Amsterdam, The Netherlands h

DHV —Consultancy and Engineering, Amersfoort, The Netherlands i

Süddeutsche Abwasserreinigungs-Ingenieur GmbH, Ulm, Germany

j

wws consulting, Reutlingen, Germany

Received 17 May 2007; accepted revised 20 November 2007

Abstract

In the future, upgrading of existing wastewater treatment plants (wwtps) will become the more challenging task than erection of wholly new plants, as most of the plants (e.g. necessary in Germany) do exist already. Since some time, MBR technology has been taken into consideration and has been realised as an alternative for wwtp upgrading.This paper gives an overview about some relevant preconditions, basic upgrading concepts and examples of already upgraded wwtps using MBR technology.

Keywords

: Municipal wastewater treatment; Upgrading; MBR technology

doi:10.1016/j.desal.2007.11.035

Ch. Brepols et al. / Desalination 231 (2008) 20–2621

1. Introduction

Many wwtps suffer from an inadequate level of treatment provided. There are several reasons for the need of retrofitted and/or upgraded equip-ment, such as expiry of lifespan, the increase of wastewater flow or load or higher treatment stan-dards due to a change of legal framework. In gen-eral, no standard solutions for the upgrading of wastewater treatment systems are available and the transfer of a certain measure from one case to another is limited. In fact, the optimum answer in each individual case is largely site-dependent. Accordingly, there is a broad spectrum of mea-sures that might be employed. In most cases it is not a singular action to be taken, but the upgrad-ing will incorporate a set of different interlocking components both at the drainage system and the wastewater treatment plant.

The MBR process is an emerging advanced wastewater treatment technology that has been successfully applied at an ever increasing num-ber of locations around the world. It involves a suspended growth activated sludge system that utilizes microporous membranes for solid/liquid separation as a substitute of the conventional sec-ondary clarifier. MBR technology has not only attracted increasing interest for the set up of new wastewater treatment systems but also it has high potential looking at upgrading tasks of already existing wwtps.

2. Considerations for the choice of MBR technology

Since membrane filtration allows raised sludge concentrations, the activated sludge tank volume can be significantly reduced. In combination with the option to convert the secondary clarifier, that is no longer required as a sedimentation tank, as an additional activated sludge tank, the treatment capacity of the existing plant can be largely ex-tended. That way it is possible to upgrade exist-ing wwtps from simple carbon removal to BNR systems just using the already existing volume.

Therefore favourable conditions for the choice of MBR technology are given, where retrofitting of the existing plant by the conventional activated sludge (CAS) process would demand for substan-tial extension of the activated sludge volume. As well, where limitations due to insufficient effi-ciency of the secondary clarification basin exist, particularly however, where both problems have to be solved.

MBR technology should also be considered if high effluent criteria such as removal of suspended solids or absence of pathogens have to be met. Examples are discharge into small creaks as well as into bathing water or other sensitive areas.

Due to the small space requirement the MBR offers special advantages if the given location holds no or only a limited amount of area in re-serve. Moreover, the small footprint allows a com-plete indoor installation in a building designed to blend in with its surrounding environment and such to address issues of visual amenity, odour or noise.

Another distinct advantage of MBR technol-ogy is direct utilisation of the effluent for reuse purposes. The water reuse potential includes irri-gation of agricultural land, recharge of aquifers or river flow replenishment. On several occasions this was the major decision criteria to opt for MBR technology.

With the choice of the MBR special attention should be paid to the fact that the investment costs are largely correlated with the hydraulic peak flow. This parameter determines the total membrane surface area which needs to be installed. There-fore, accompanying measures to minimize wet weather flow or to harmonise resultant wastewa-ter largely contribute to cost effectiveness of the MBR approach. One option for dealing with high wet weather peaks is to use the former secondary clarifier as storage volume. Another option is hy-brid systems where the conventional system is used as a backup to treat the inflow volume that exceeds the hydraulic membrane capacity. An al-ready realised hybrid concept designs the MBR