Using simple technologies to recycle grey laundry water

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Have a good day everyone,

I have been searching for treating laundry grey water with a decentralized water recycling system.

I saw a simple system with basic elements. It used a filtration system, a pump, of course, micro plumbing, a tank for storage, and U/V between tank and washer. 

Laundry usage picks up a vast amount of contaminants and I think the researchers already knew that cathing up the clean profile of starting water requires changes, improvements for the system and of course, also, filtration alone wouldn't be enough. I don't see or reach further studies of this research but this left me very curious.

I would like to know how this kind of system would be improved. 

What are your suggestions? 

I am ​very ​curious about ​that and I ​would like to ​hear some ideas. ​ 

Thanks in ​advance, it is ​appreciated. ​

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15 Answers

  1. A lot of intricate details are being researched on laundry wash water as influent to appropriate wwt plants.

    1. Have washings also on gradings ie most soiled to least soiled.

    2. Use the minimum cleaning liquids if possible use bio cleaners 

    3. For de oiling use hot or very hot water.

    4. Where vacuum cleaning is possible, go:for it. 

    5. Inter space all machines with greens to absorb niose vibrations and dust too.

    Well wishes ..

  2. Regarding ozonation of greywater - many years ago (1997) I used an Osmonics ozone pilot to pretreat denim wastewater before my fixed-film bioreactor pilot … at a large blue jean production facility ...with the following results, as best I remember:

    1.  Ozone worked well to remove soluble COD in the blue (indigo) laundry water, with close to 4-5 g  COD removed per g O3 generated … this was surprisingly high ratio … and some stripping of volatile COD may have been part of the explanation.

    2.  Ozone helped reduce polymer consumption in the DAF units, especially when dosed in higher quantities, even eliminating the need for polymers at high ozone dosage.

    3.  Ozone had some effect in dropping pH in the wastewater. 

    Overall the ozone worked very well in conjunction with my fixed-film bioreactors when used up front of them.  I would expect O3 to work well after bioreacters or filters as a disinfection step.

  3. I have several installed wwt systems on industrial laundries and one extended pilot for laundry/shower/kitchen gray water treatment.  Basically we used rotary screens to remove most lint, dissolved air floatation to remove fine lint and oils, fixed-film bioreactors to remove all soluble biodegradable detergents and conditioners and some dyes, dissolved air floatation to remove biosolids.  At the industrial laundries between 65-85% of this treated water is recycled to the washing machines.  No treated water can be recycled to dye houses (in applications with apparel production) because some dye solutions are very particular and require sulfate free water.

    In the extended pilot we added a microfiltration membrane to produce treated water of very high quality with turbidity less than 2 ntu's.  This water after microfiltration could be further treated by ultrafiltration if reuse standards required it. 

  4. Update:

    Thank you for sharing ideas.

    I appreciated it. 

    I wonder how this system would work with an ozone generator. Is it possible to add an ozone generator to the system and use this ozone generator for both washing clothes and removing contaminants in the water before filtration? Would it be appropriate to use this generator also for the storage tank later? I mean for final disinfection. In this way, can we get outlet water quality close to the starting water quality? The aim is to reuse the water as much as possible.

     

    Thank you.

  5. We market a system that will remove the suspended solids cost effectively.  The technology is very robust and has been used successfully on many different effluent streams.  Depending on the quality of water that you want for re-use, you could then add a filtration system downstream to remove the dissolved solids.  Look at the technology here www.abrimix.co.za.  

     

  6. Dear Researchers.

    In a Forest Resort for 50 occupants in 15 to 20 hut type houses, grey wwtp was designed on Dewats principle.

    Use bio cleanrs for both laundry and kitchen/ pantry also bathing wash water.

    Use of hot water as degreasers is encouraged. 

    The use is around 100lit per gpcday . 

    On full load it is 5kl perday and accordingly desigmed.

    All effluent is reused for site use.

    When needed the desigm can be upscaled. Wwtp is also appearing green on surface .

    Well wishe.

  7. I will agree with other comments made that liunbt will be a factor needing to be dealt with, because it will cause clogging issues for most type fo cleaning sstems.

     

    Once the lint is taken care or, you can always look at Treatment Wetlands.  Once the water is charcterized and we known exactly what is in it, we can look at he type or ype of treatment wetland to the used.

     

    In its design, beyond the buildign costs of the wetland, the O&M is rather low as electrical, chemical, replacement parts and and labor is low or none.

  8. There will always be partial solutions to simple recycling of trash and water. You may want to start with an RNA based microbe. This will eliminate all residue, lint and any harmful compounds found. Best to be used as compost water or reuse for next batch of clothes washing, It will be that clean.

  9. Key issues in laundry waste water are lint,residual chemicals and temperature.A collection tank could help in lowering the temperature to an extend.Lint removal with units like vibratory screen is necessary.Use of coagulants need to be limited ,since TDS is a key issue in the laundry water for quality of wash .Probably sand ,carbon and micro filtration will ensure reasonable quality for partial recycle .100% recycle has been a challenge and the presence of cationic chemicals in the wash composition does impact RO membranes performance and life.These observations are based on my personal experience with laundry waste water recycle in Middle East and India.

  11. You will typically require a coagulant upstream of the filtration system, be it MMF or UF. It is advisable to automate the coagulant addition by using a streaming current monitor so as to optimise the dosage and to ensure optimum organic removal. 

    I'm assuming the wash cycle water is being discarded and it's only the rinse water that is being recycled, so residual surfactant won't be an issue. 

    It isn't necessary to perform RO or disinfection if your intention is to reuse the water in the laundry. 

  12. If you 'spin dry', much of the macro size lint can be trapped and removed with a screen filter, as found on most washing machines. The micro natural and inorganic lint in the greywater may well be broken down by micro-organisms in a planted (anything with decent roots; Canna sp., etc) constructed gravel bed wetland (CW) that is ~50 cm deep. Use larger (3"-4" rock) stone (25% of total amount of CW), followed by small pea gravel (

  14. Dear Aysegul

    Laundry WW contains a huge amount of lint that for sure will clog and put your filtration system out of order. you need to separate the problem to two issues one is the lint that you need to filter out and the other is the microbiology (for which you can use UV, electrolysis or other methods) beware not to add chemicals that might harm the laundry process. for the lint, I have used electro floatation and successfully lowered the NTU from 220 to about 2. you may be referred to my website www.wtr-t.com

    Best

    Menashe

  15. Intuition tells me to use in addition to filtration ozone Ultra Fine Bubbles/Fine Bubbles to recycle this gray water.

    1 Comment

    1. All the above processes tend to target the removal of undesirable physical characteristics more than dealing efficiently with the removal of the chemical undesirables of the detergents used in the laundry process. Analysis of detergents used is very important and each treatment process used may be unique given the varieties of products now in place for use in laundries and the various concentrations used for each product. Removal of lint and other physical undesirables is good if the water for the laundry is to be recycled for laundry and non agricultural or non consumptive purposes only