Greywater Trickling filter system

You will first have to consult the applicable laws.

In SA you are for example only allowed to dispose of the grey water for one household by means of a soak-away (trickling filter). A communal conservancy tank may serve up to 50 households. Evaporation dams or dams for storage (5000 m^{3 )} for reuse (irrigation of crops) is allowed.

Trickling filters for small flows come in very compact packages and can be very inexpensive to install and operate. In fact, the long term cost is much lower than their equivalent extended-air activated sludge systems. There are several companies which manufacture or assemble treatment plant packages based on TF. One of them is ORENCO, which uses a synthetic fabric medium to promote attached bacterial growth. They can be found on the web.

The first phase of a subdivision we designed in New Mexico included a small TF treatment plant, with a capacity equivalent to 15,000 GPD at 210 mg/l. Incidentally, I use the equivalence because water use restrictions, for conservation purposes, can be very strict in this part of the world, and small flows will have higher solid concentrations. The equipment was supplied by a small manufacturer in Taos, New Mexico by the name of KOI Environmental. KOI uses a very simple "packing peanuts" growth medium. These peanuts"" are placed in plastic nets, which in turn are placed inside a cylindrical fyberglass tank with a conical bottom.

The second phase, currently under construction, is being supplied by Orenco, primarily because we specified for performance, and Orenco provided a better bang for the buck.

There were some concerns in the past about the Orenco plants failing, because the fabric stretched with the weight of the water, to the point where the units became septic. The mfg has made efforts to solve the problems, and seems to stands behind their equipment 100%. It would be prudent, however, that you also verify the mfg claims, with those clients with whom they had to make amends. The New Mexico Environment Department has a record of the facilities which have used one of these sytems in the past, and they can provide some insight on the matter.

Ciao

Are you actually planning to design it yourself or are you just looking for information to provide to your contractor? If you're planning to design it yourself, better not to try it if you didn't study water engineering. The equations involved are pretty complex. On the other hand, if you just need information to supply to a contractor, then I hope you find the following useful.

1. You'll need to specify your normal and peak hour flows so that the engineer will be able to calculate the surface loading rate.
2. You'll have to provide your wastewater pollutant concentration level, particularly BOD & NH₃ levels, and the required removal efficiency (e.g. 95%).
3. You'll also need to specify whether you want to have a high rate or low rate system, with or without a recirculation system, and whether it is a single-pass or turnover system. If it is to be a turnover system, you'll need to specify the turnover rate (how many cycles per hour). If you want to include a recirculation system, then you'll have to specify how much treated effluent is to be cycled back to the influent to dilute it. Generally speaking, 50% is good for most domestic purposes. Recirculation and turnover gives you a better quality effluent, but must be sized larger to compensate for the increased influent flow.
4. You'll have to specify the maximum allowable floor loading and maximum allowed footprint area are where the filter is to be located as well so that the design engineer can determine the optimum cross-sectional area to meet your specifications.
5. Specify what sort of material you want to use for the media bed. If you leave it to the engineer, he'll probably use granite aggregate as it is cheap. However, it will also result in a very large and heavy system as granite aggregate has a fairly low specific surface area.

I hope you found the above useful. If you have any doubts or any other questions, don't hesitate to ask me. I am always willing to help anyone who asks for it, as long as they don't ask stupid questions like how to design a system that can extract cosmic rays from the stars to generate free energy.

The first poster was right - definitely check local laws first. I know several states in the US don't allow any greywater use. Usually outdated sanitation laws because of things like cholera and other waterborne diseases or environmental concerns.

A while back, I attended a presentation in Panama by

Michael Ogden <michael@natsys-inc.com>

Natural Systems International, Inc
3600 Cerrillos Rd., Suite 1102
Santa Fe,NM 87507

tel: 505 988 7453

email: nsi@natsys-inc.com

web:www.natsys-inc.com

They are quite knowledgeable in such systems, and have apparently designed many facilities for water reuse throughout the United States. They are also most likely to be cognizant of local laws and regulations for any US application of such technology.

Check out www.filterboxx.com. They custom build stuff. Their specialty is being high quality and portable. I.e. build off site, bring it there and plug and play. They're doing some oilfield camp jobs with us. Ground water treatment and Wastewater treatment, but they custom build to suit. I'm a mechanical engineer, so I can't comment much on the details.

Evan

Dear Kate,

You need to read http://en.wikipedia.org/wiki/Greywater to start with.

You say you want to use a trickling filter.

2200 gallons per day is a lot of water. From an institution/hotel? Not from a home!!

Q's

1. After TRICKLE Filtering what do you want to do with the filteredwater?
2. A trickle filter may really TRICKLE .This may mean you may have a very large holding/filtering real estate blocked up.

If you want a rapid removal of washing/domestic wastes(not Septic) you should go for an ElectroCoagulation system(Google it) with skimoff of floatsum.

BR

MM

Hi,

Trying not to sound too critical, it appears that you have arrived a decision as to the correct waste water solution without the benefit of detailed research?

All valid points. Additionally I would want to know where does the effluent from the tf go? Ground water recharge, holding tank, additional polishing, to the river, run, kill, or whatever it is called in your part of the world? Often transferring water from one basin to another is not well regarded. Please be kind and recycle.