Filter is clogging and I need to make a sedimentation tank

hello guys, i was given a filter to filter out the grey water coming from my cow farm but there still is big particle that are clogging my filter even though it hs a backwash system I was thinking of makinking a sedimentation tank to solve this problem. my farm produces around 10,000 L of black/grey water a day.

Welcome to Permies Farid.

Look at using the effluent to generate biogas which will get rid of most of the bacteria and provide power.  This will not need to be filtered.  India has some excellent examples or rural community biodigesters to make home gas and electricity.  Then construct a large multi-stage ponding system (reed bed), where the end result is clean usable water.  A reed bed would clean up the other waste with usable water being the end result.  The byproducts of the system can be fish and edible water plants. The waste from the biogas generation can be used on the fields or packaged and sold as fertiliser

We have a domestic reed bed which we built ourselves and the animals prefer to drink out of this rather than tap water.  There is no smell from our system.  

Best wishes with your project.  We look forward to seeing your progress.

Could you expand on your system and how it currently works? What kind of filter are you utilizing?

Sedimentation tanks are an option in my mind.

For a sedimentation tank, you have to consider if 10,000 liters per day is 7 liters per minute, or if it all arrives at the sedimentation tank in one hour; the settling time is based on the flow and the tank size. It sounds like your water is fairly high in organic waste, so when sediment accumulates, it may sometimes produce gas bubbles and float. You will want the sedimentation tank overflow pipe to start with a tee, so floating stuff doesn't leave with the overflow. Most sediment will drop out within thirty minutes, and because settling particles reach a terminal velocity in the water, a shallow tank gives better results (albeit requires more area to have the same volume). To have a settling time of 30 minutes, with a steady flow of 7 lpm, you need a 210 liter tank with perfect diffusion of flow - no short circuiting currents. Since perfect diffusion is almost impossible, you will want to over-size the tank - or since drums are so commonly available - divide the flow between two drums. Where the water enters the drum, ease it in with a pipe that extends below the water surface where it is capped, and perforate the below-surface part of the pipe with numerous large holes. Water will not stir up sediment at the bottom and will not otherwise cause a single prevalent current across the tank.

Flow splitting is difficult to do well. The easiest way to make it accurate and easy-to-maintain, is make a splitter box where the total flow enters and there are two (or more) overflow pipes set at the same elevation - one to each tank. Each pipe can have a V-notch cut into it, so they start overflowing at the same water elevation and stay matched as the water level rises. You can make the pipe levels adjustable by having the pipes mounted in the splitter box with flexible rubber couplings - the pipes can be raised or lowered to balance flow.

You will want a sediment drain on each tank. Since you will drain sediment from a full tank, normally, the sediment drain can enter the side of the tank and have an elbow downward to near the tank center. Siphoning in this pipe will let you draw sediment and water from close to the tank bottom - as close as a centimeter or so.

The tank is doable but expensive. Worse yet, it still may not work as well as you might like. . My first action would be a pre filter or fine screen placed in front if the filter that could be emptied once or twice a day.

Hi Farid. Is this washdown water from a milking plant and the pad leading to it? Lots of dairy farms here are putting in systems that reuse the wash water with a settling pond and a solids removal process using a pump and a screen. This allows them to reduce the amount they need to pump from bores as well as limit what gets discharged to a bare minimum. The separated solids are collected and spread on the paddocks to return fertility to the soil.

John F Dean wrote:The tank is doable but expensive. Worse yet, it still may not work as well as you might like. . My first action would be a pre filter or fine screen placed in front if the filter that could be emptied once or twice a day.

it's clogging after 3 minutes of activation as you can see in these images

You haven't explained what the source of your water is clearly, but wouldn't water contaminated with animal waste be more rightly considered "black" water rather than grey?

The terminology matters, because they get handled differently and with different solutions needed. For example, grey water is usually considers safe to use for immediate landscape irrigation (provided that appropriate plant safe detergents are used). Black water is not safe for irrigation needs - it has high pathogen loads, and a risk of contaminating ground water. It needs treatment before use.

I suspect that you won't get any very useful answers here unless we have a much clearer understanding of what your water is contaminated with, and what you intended to use it for afterwards.

Michael Cox wrote:You haven't explained what the source of your water is clearly, but wouldn't water contaminated with animal waste be more rightly considered "black" water rather than grey?

The terminology matters, because they get handled differently and with different solutions needed. For example, grey water is usually considers safe to use for immediate landscape irrigation (provided that appropriate plant safe detergents are used). Black water is not safe for irrigation needs - it has high pathogen loads, and a risk of contaminating ground water. It needs treatment before use.

I suspect that you won't get any very useful answers here unless we have a much clearer understanding of what your water is contaminated with, and what you intended to use it for afterwards.

message received, you're right the water is sourced from my manures press machines wish separates the solids and liquids of fresh cow manure daily, which I presume can be referred to as black water, I have attached a picture showing the water extracted after the process

The last time I saw something similar used, settling was handled through an open “lagoon” (pond) that had a diameter of at least 100 feet. That, of course, brings in safety and zoning issues .

Handling of such black water is likely to be pretty tightly regulated - you probably have specific legal obligations to ensure it doesn't contaminate ground water and streams for example. Those regulations may spell out restrictions on how it should be handled.

As for your observation about filters clogging - I'm not at all surprised, based on what we see in that picture. Sedimentation tanks would certainly be an improvement over stepping directly to filtration.  Such tanks need to be sized based on the expected water flow.

Does it come steadily through the day, or in one large batch?

Sedimentation essentially needs the water to be stationary, or near stationary, for an extended period of time. There are two approaches.

In a batch system you would fill a tank up, then let it sit for 24 hours or so. Most of the worst sediment would settle, then you drain the water.

In a through flow system you have a slow but steady feed of water into a wide, deep tank. A corresponding slow trickle of water leaves the far side, and in between the water is near stationary so sediment can settle out. To size such a system you need a good understanding of flow rates, how quickly your sediment will settle out, and a way to ensure that the water feed in is very low velocity so that it doesn't agitate the water on entry.

In either case, you need a suitable drain for clearing out the sludge that doesn't involve someone climbing in the tank. The gases produced by slurry tanks are notorious for killing farmers who climb in to clean things and asphyxiate. The sludge produces CO2, ammonia, and NOx displacing the oxygen.

I think you can see that this is a fairly complex topic, and one which you don't want to get wrong. I would see if you can seek advice from other farmers in your area to see what they do, rather than try and design your own without more specialist input.