Benefits of Electrocoagulation for Hotel Grey Water Reuse

grey water

Most summers, our family takes a week-long vacation in North Myrtle Beach, SC, USA. We typically stay in a oceanside hotel, and we spend all day, every day out on the beach under the sun. By the time we come in for the day for dinner, we’re covered in salt and sunscreen from head to toe and in desperate need of a shower. Showering is an event. There’s six of us plus any friends that come along and more often than not there are only one or two showers. It takes about two hours to get everyone clean. Two hours of running water is a lot. But we also have to brush our teeth, wash our hands, cook dinner, wash dishes, and do laundry. The grey water generated is substantial.

That’s for a single family. Hotels & resorts can house hundreds of families all using water for the same purposes.

However, there’s also housekeeping to consider. They clean and wash bed sheets after one family vacates a room. All in all, there are thousands of gallons of water that are consumed during a single day of operation in a hotel. The cost of water use may or may not be the most substantial of a hotel’s operating costs depending on its location, however, reducing this particular operating cost could add a noticeable increase to a hotel’s net profit.

One of the most effective ways to reduce water consumption, is to treat and reuse grey water or wastewater.

Gray water reuse is not only beneficial to the operating costs of hotels, but it is also a more efficient and sustainable way to use water.

What is Grey water?

The wastewater resulting from the activities mentioned above is known as grey water. It differs from other domestic wastewater because it is typically cleaner, as it does not contain fecal matter from toilets. This fact makes grey water easier to treat than domestic sewage, with fewer solids and pathogens. In addition, with few contaminants to treat, grey water is a great source for reusable water, requiring less energy to treat and reuse. This gray water, can be reused for land irrigation, laundry, toilet water, cooling towers, or cleaning water. Basically most non-potable applications.

How can this Grey water be treated?

One avenue for the treatment of grey water for reuse is to utilize electrocoagulation (EC) as part of a grey water treatment system. EC has been used in many industrial applications to great effect, and so it can certainly be effective for grey water treatment & reuse.

It works by supplying current to an array of metal electrodes (typically iron or aluminum or both). From within the solution, the anode oxidizes and releases ions into the effluent that neutralize the overall charge of the solution. At a neutral charge, particles will no longer repel one another and will coagulate. On the other side, the cathode reduces the water and causes hydrogen gas bubbles to form and rise to the surface, carrying these coagulated particles, like oils and solids to the surface where they form a floc layer.

So how does this work for grey water contaminants?

This research presentation from an institute in India has some great information on how EC works and its removal efficiencies for COD, BOD, turbidity, and coliforms. Grey water can contain hardness, silica, and sulfate, and while it does not have the same levels as toilet water, gray water does contain some level of pathogens (measured in fecal coliform and total coliform concentrations).

Hardness, silica, and sulfate are all precipitated out of suspension as solids during the destabilization and end up as sludge separated in a post EC clarification process. As for any bacteria, the electricity and oxidation actually weakens cell membranes and kills them.

Studies have shown EC to eliminate up to 100% of E. coli bacteria and coliform bacteria in wastewater samples.

Therefore, aside from the obvious benefit of water reuse and the removal of the contaminants, EC treatment of gray water has several additional noted benefits.

* Number one is the cost.

EC systems can be compact, easy to install, relatively easy to operate, and easy to maintain. These systems do not have moving parts to break or maintain.

Systems like Genesis Water Technologies specialized modular units are typically automated, easy to install, and can be utilized in new process systems or retrofitted into existing processes. These systems may not typically require pH adjustment in greywater applications to run efficiently.

Maintenance mostly consists of cleaning electrodes which can be automated, and replacing the sacrificial electrodes after they have been worn down. Good maintenance and usage of optimized current can make them last for some time.

* Number two is the sludge.

In most instances of wastewater treatment, sludge is a hassle to deal with. Using a conventional chemical treatment approach yield a lot of it, and it is usually toxic. However with EC, especially when used with greywater, there is very little sludge produced and whatever sludge is produced is non-toxic. In fact, it can make really good fertilizer after it is dewatered, which could be useful for any plants around the hotel.

* Number three is the power usage.

You would think that something that uses electricity as its main operating mechanism, would use a lot of it, however, it can actually use less than other systems. The current required for gray water reuse can be quite low. The system can treat greater than 50% of the contaminants in five to ten minutes with optimized power usage.

* Number four is EC works quickly, especially on greywater.

Chlorine disinfection can take 30 minutes to work completely, and this is only for disinfection purposes. EC can remove greater than 80% of all of the contaminants in the same time it takes chlorine to kill off only bacteria.

Are you in the hotel/resort industry and want to learn more about how specialized electrocoagulation can help you lower your operating costs and be more sustainable?

Contact Genesis Water Technologies at 1 877 267 3699 in the USA or via email at for a free initial consultation to discuss your gray water treatment applications.