Available online at www sciencedirect com Chemosphere 71 2008 147 155 www elsevier com locate chemosphere Technical Note Chemical solutions for greywater recycling Marc Pidou a Lisa Avery a Tom Stephenson b Paul Je rey a Simon A Parsons a Shuming Liu c Fayyaz A Memon c Bruce Je erson a a Centre for Water Science School of Applied Sciences Cran eld University Cran eld MK43 0AL United Kingdom b School of Applied Sciences Cran eld University Cran eld MK43 0AL United Kingdom c School of Engineering Computer Science and Mathematics University of Exeter Exeter EX4 4QF United Kingdom Received 15 August 2006 received in revised form 24 October 2007 accepted 24 October 2007 Available online 21 December 2007 Abstract Greywater recycling is now accepted as a sustainable solution to the general increase of the fresh water demand water shortages and for environment protection However the majority of the suggested treatments are biological and such technologies can be a ected especially at small scale by the variability in strength and ow of the greywater and potential shock loading This investigation presents the study of alternative processes coagulation and magnetic ion exchange resin for the treatment of greywater for reuse The potential of these processes as well as the in uence of parameters such as coagulant or resin dose pH or contact time were investigated for the treatment of two greywaters of low and high organic strengths The results obtained revealed that magnetic ion exchange resin and coagulation were suitable treatment solutions for low strength greywater sources However they were unable to achieve the required level of treatment for the reuse of medium to high strength greywaters Consequently these processes could only be considered as an option for greywater recycling in speci c conditions that is to say in case of low organic strength greywater or less stringent standards for reuse 2007 Elsevier Ltd All rights reserved Keywords Coagulation Greywater Magnetic ion exchange resin Recycling 1 Introduction Interest in wastewater recycling has been raised by the increase of water demand water shortage due to low rainfall economic and environmental issues Eriksson et al 2002 Among the di erent options for water reuse such as industrial irrigation and ground water recharge water recycling within urban environments is the least developed Urban recycling usually integrates the reuse of black grey or rain waters Greywater is de ned as domestic wastewater excluding water from the toilet and generally includes wastewaters from baths showers hand basins washing machines dishwashers and kitchen sinks However at small scale the heavily polluted sources such as washing Corresponding author Tel 44 0 1234 750111 fax 44 0 1234 75167 E mail address b je erson cran eld ac uk B Je erson 0045 6535 see front matter 2007 Elsevier Ltd All rights reserved doi 10 1016 j chemosphere 2007 10 046 machines dishwashers and kitchen sinks tend to be excluded whereas at larger scale all sources are used to maximize water savings The most common application for greywater reuse is toilet ushing which can reduce water demand within dwellings by up to 30 Karpiscak et al 1990 However other applications such as irrigation of parks school yards cemeteries and golf courses vehicle washing re protection and air conditioning are practiced Lu and Leung 2003 The water quality standards for wastewater recycling depend on location and application but generally include parameters based on organic solids and microbiological contents of the water The most stringent criteria require a biochemical oxygen demand BOD of less than 10 mg l 1 a turbidity below 2 NTU and a nondetectable level of either total or faecal coliforms USEPA 2004 Tajima 2005 However other standards which are less restrictive allow higher concentrations of the di erent parameters or do not include some of the parameters at all USEPA 2004 Gross et al 2007 148 M Pidou et al Chemosphere 71 2008 147 155 A large range of technologies has been used for greywater recycling from simple 2 stage processes coarse ltration and disinfection to physical physicochemical and biological processes Je erson et al 2000 The latter widely used in large building Santala et al 1998 Surendran and Wheatley 1998 Nolde 1999 Friedler et al 2004 su er from feed source variability and potential shock loading at smaller scale Such problems are avoided with simple physical processes such as cartridge lters or depth ltration beds However whilst these are e ective at removing the physical pollution within the greywater they do not signi cantly alter the organic fraction Je erson et al 2000 As such chemical processes such as coagulation and adsorption provide great potential for the removal of the dissolved organic fraction within greywater Indeed coagulation with metal salts remains the main process utilised in the potable water treatment eld for the removal of high concentrations of dissolved organic carbon DOC Parsons and Je erson 2006 In more recent times a novel magnetic ion exchange resin MIEX has been trialled and is being used to reduce organic loads onto some water treatment works to reduce coagulant demand or improve the structural properties of the ocs produced Je erson et al 2004a In opposition to traditional ion exchange resins MIEX has a magnetic component in its structure which facilitates agglomeration and settling Moreover with an average particle size of 180 lm 2 5 times smaller than traditional ion exchange resins MIEX has a high surface area for adsorption And nally it is designed to be added to the water as slurry in a mixed reactor The particles dispersed in the water maximise the contact with the organics reducing the contact time needed compare to a xed bed set up Boyer and Singer 2005 The aim of the present work is to assess the potential for utilise these chemical processes for greywater recycling 2 Material and methods 2 1 Sampling Greywater was collected from a purpose built facility which diverts water from the bath shower and hand basin of 18 ats within a student hall of residence located at Cran eld University This source water was de ned as the mixed source in the subsequent experiments As an alternative shower water was also collected from a single location Care was taken to standardise the products used with respect to their concentration and the duration of the shower between samples Samples were taken on the morning that the shower was used with all the
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