I have a customer who asked us to help them to recycle the water used in the laundry process (washing clothes and linen). They want to use the water in the laundry process again once recycled.
The daily water usage is 600 liters per day total from 7 different industrial type washing machines.
Can Ultra Filtration and Carbon Block technologies recycle the water back to the desired state?
How about the soap and bleach elements, how to take care of these?
How many times can the water be recycled through this process?
Shawn; the issue will be temperature, TSS and oils and grease. since the water recycled will come from various sources the opportunity for cross contamination and "surprise" feed water changes will be a common occurrence, standard PVDF UF membranes will not be tolerant to this and will fail quickly. Most recycle operations utilize a ceramic UF to tolerate the higher temps and oils. Cost would be prohibitive for a 600 l/day system. You can use carbon block and standard filtration to treat the wash stream and reuse the water in the rinse cycle. some sort of dosing will be required to control chemistry and odor. Typically you will see a 50-60% reuse rate before you start to get diminishing returns. ljessup@kemcosystems.com
I am no expert on treatment of this industrial effluent, but home laundry would have grit and solids, organics, fecal coliforms, and detergents, at least; in lower concentrations than domestic sewage, but similar in general quality. The detergents are certainly biodegradable. I did lots of experiments with them in graduate school back in the day. That suggests that biological treatment may be a more cost-effective solution than chemical treatment, especially if life-cycle costs and environmental consequences of the manufacture of the chemicals are considered. Could be a good application for a membrane bioreactor. The UF membranes may do a good enough job at disinfection that post secondary disinfection may not be required.
Hi Shawn, glad to make an introduction to Chris Gilreath, CEO at Recycled Hydro Solutions as he should be knowledgable about your concerns and able to expertly comment. RHS use a process to strip bacteria from "dipper wells" in ice cream shops. Let me know now how to connect you, via Linkedin or per e-mail and revert. Disclosure; I have no affiliations or interests in RHS. He is a personal friend through the Cleantech Open.
we have some experience on Ultrafiltration use for industrial washwater recycling (not exactly laundry). Recycling reasonable portions of the water used is working well, non-bound detergents could be recovered as well but not the detergents bound to the waste. Maximes hint on membrane materials is helpful, no doubt. The amount/concentrations of phosphate you have to deal with is highly depending on the place of our globe your plant is working. We have very low phophate concentrations in EU wastewaters, but that is not the case in other regions. As phosphate is able to pass the UF membranes you should not have any concentrating effects leading to scaling even if you have that high amounts mentionend by Oksana.
UF would be a great solution to recycle 70-80% of the volume and soap and heat however at 600l/day would the investment be viable? The condition are ideal for UF too hot effluent low TSS be careful with oxidant on polymeric membrane but most of all fibres textile fibres that can rapidly clog spiral configuration
reusing the rinse water for the next washing cycle is a great idea & easy. Both could be combined.
The best way we use is a simple gravel filled greywater wetland system. This is a proven and very effective system to achieve all you want. Contact me if you want more details.
We are proposing solutions for recycling laundry water. Please send me a email with your contacts informations that we get in contact to discuss about your needs.
This isn't my area of expertise, so I haven't got a perfect solution for you. Instead here are a few comments that might be useful.
Ultrafiltration is probably the right direction to go. This will generate a concentrated waste stream, so you cannot recycle 100% of your wastewater. The goal shouldn't be to eliminate all liquid waste, but to reduce fresh water intake. You're probably looking at 60-70% recovery, very rough estimates.
Be mindful of the types of membranes you use. Bleach will damage typical polymeric membranes. May be worth looking into ceramic membranes, more costly at purchase, but cheaper in the long run. Activated carbon may not be required at all with the right membranes.
as far as I know from that article http://file.scirp.org/Html/2-2200743_41855.htm Phosphate was detected in 93% of the samples (94.65 mg∙L−1 average); its strong presence was most likely due to the laundry water contents. We have tested Vortex Layer Technology to remove phosphates from wastewater here is the link to video-report https://youtu.be/jMmrMCwZdf8 and full article is here https://avs.globecore.com/removal-phosphates-waste-water.html