Russell griffiths Posted June 9, 2018 Share Posted June 9, 2018 Could anybody tell me why I shouldn’t direct a portion of my rainwater into my treatment plant. I will tell you what I’m thinking. Our treatment plant will discharge into a small nature pond I have just constructed, now there are only two of us in the house so fairly low discharge coming out into the pond, I am concerned about it drying out in warmer weather and thought a flush through of some rainwater will keep it topped up. So what harm am I going to do to all the good bacteria stuff in the treatment plant if they get a dose of nice clean water. Cheers russ. Link to comment Share on other sites More sharing options...
Nickfromwales Posted June 9, 2018 Share Posted June 9, 2018 Just run the rainwater to the pond ? 1 1 Link to comment Share on other sites More sharing options...
Onoff Posted June 9, 2018 Share Posted June 9, 2018 18 minutes ago, Nickfromwales said: Just run the rainwater to the pond ? But that'll bypass the treatment plant that he wants to keep "wet". Link to comment Share on other sites More sharing options...
Nickfromwales Posted June 9, 2018 Share Posted June 9, 2018 Reads that it's the pond drying out that's the issue to me. . How would you gauge a bit of rainfall ? It's either all of it or none? Sleep time, too tired to think anymore. . Link to comment Share on other sites More sharing options...
Onoff Posted June 9, 2018 Share Posted June 9, 2018 4 minutes ago, Nickfromwales said: Reads that it's the pond drying out that's the issue to me. . How would you gauge a bit of rainfall ? It's either all of it or none? Sleep time, too tired to think anymore. . You no read op pwopery! Link to comment Share on other sites More sharing options...
Ian Posted June 10, 2018 Share Posted June 10, 2018 6 hours ago, Nickfromwales said: Just run the rainwater to the pond ? +1 I’ve done several larger commercial jobs which needed surface water attenuation where we took all the rainwater off the roofs and piped it to a pond. The extra bit you then need is an overflow weir from the pond which is piped to a traditional soakaway or to SW mains sewer. Link to comment Share on other sites More sharing options...
nod Posted June 10, 2018 Share Posted June 10, 2018 9 hours ago, Russell griffiths said: Could anybody tell me why I shouldn’t direct a portion of my rainwater into my treatment plant. I will tell you what I’m thinking. Our treatment plant will discharge into a small nature pond I have just constructed, now there are only two of us in the house so fairly low discharge coming out into the pond, I am concerned about it drying out in warmer weather and thought a flush through of some rainwater will keep it topped up. So what harm am I going to do to all the good bacteria stuff in the treatment plant if they get a dose of nice clean water. Cheers russ. Hi Russ we have had exactly the same dilemma We were told that over sizing is a bad thing Only two of in a five bed house Three bathrooms We were recompense a nine pop plant So we have diverted the rainwater from one side of the house To the manhole servicing the treatment plant Link to comment Share on other sites More sharing options...
Russell griffiths Posted June 10, 2018 Author Share Posted June 10, 2018 Ok more info. I have 3 roofs on the house so it will be easy to take say 2 downpipes and split them off and direct towards the treatment plant. I have thought about running straight to the pond, but the route to the pond is directly past the plant, which leaves very little land to run a second pipe past the plant, there is also the distance involved. If I can connect the house side of the plant it will save an additional trench of 30m plus all the pipe, I know the pipe is not expensive it’s the agro of the additional trench and work I’m thinking of. What im thinking is what harm could I do to the treatment plant with this flush of clean water. Cheers russ. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted June 10, 2018 Share Posted June 10, 2018 It's not at all good to run excess water through a treatment plant, as it will dilute the nutrient concentration which will then dilute the aerobic bacteria population, meaning that when a flush of nutrient enters the tank there may be insufficient bacteria to quickly consume it. If fresh water then flushes through the tank it could very easily end up washing partially-digested material through the outlet. If that outlet is running to a watercourse, then there is a significant risk that discharging high biological oxygen demand waste could have an adverse impact on the watercourse. 2 Link to comment Share on other sites More sharing options...
Russell griffiths Posted June 10, 2018 Author Share Posted June 10, 2018 Top man @JSHarris I was hoping you would comment Link to comment Share on other sites More sharing options...
Russell griffiths Posted June 10, 2018 Author Share Posted June 10, 2018 If you have any more info on this and the time I would be interested @JSHarris Link to comment Share on other sites More sharing options...
Jeremy Harris Posted June 10, 2018 Share Posted June 10, 2018 Really just that the general rule is to try to maintain a high nutrient level in a treatment plant with a throughput of effluent that is matched as closely as possible to the size of the tank. Over sizing the unit is not good, for the same reason as putting too much water through a unit, it dilutes the nutrient content. I think it's best to try and deal with rainwater run off with either a soakaway, or some form of surge storage system. We had to use the latter, because of the proximity of the stream (it's about 6 or 7m from our front door), and as we didn't have room for a surge storage pond we ended up burying twenty 196 litre Aquacell crates under the drive, to give us nearly 4000 litres of surge storage capacity. This drains to the stream slowly, via a permeable soil layer, so complies with the SuDS rules. Link to comment Share on other sites More sharing options...
ProDave Posted June 10, 2018 Share Posted June 10, 2018 Just to be clear, th treatment plant will not "dry out" If the objective is to stop the pond drying out, then run the rainwater to it, but you will need a mechanism to stop the pond over filling which may be as simple as a weir that allows the pond water to run off somewhere else if the level gets too high, though it would be better to divert the rainwater away from the pond in that situation. Link to comment Share on other sites More sharing options...
Nickfromwales Posted June 10, 2018 Share Posted June 10, 2018 My take would be to discharge to the pond and pump back to the plant from the pond when necessary. Maybe that could be automated ? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted June 10, 2018 Share Posted June 10, 2018 There should never be a need to pump fresh water from a pond to a treatment plant, as the treatment plant will sit full of water/effluent/bacteria even with no input for a few weeks. If left unused for months then the bacterial population will die down, leaving the tank full of treated effluent with a low BOD, and there will be a delay when effluent reaches the treatment plant again before the bacterial population has had a time to multiply up, but as the resting BOD of the tank contents will be much lower than the limit, it can take usually tolerate this time delay without significantly exceeding the discharge BOD limit. Link to comment Share on other sites More sharing options...
dpmiller Posted June 10, 2018 Share Posted June 10, 2018 some systems (many?) also have a holiday mode to slow down the process when there's little or no input. Link to comment Share on other sites More sharing options...
joe90 Posted June 11, 2018 Share Posted June 11, 2018 As I put in a different thread, our six person treatment plant ( three bed house) will mostly have only the two of us and that’s why I chose a vortex that can be “ turned down” to match the input, the commissioning bloke said lack of food ( poo) will adversely affect the efficiency of the plant ( I.e. too much water). Link to comment Share on other sites More sharing options...
ProDave Posted June 11, 2018 Share Posted June 11, 2018 2 hours ago, joe90 said: As I put in a different thread, our six person treatment plant ( three bed house) will mostly have only the two of us and that’s why I chose a vortex that can be “ turned down” to match the input, the commissioning bloke said lack of food ( poo) will adversely affect the efficiency of the plant ( I.e. too much water). Is that done by just turning the pump on and off on a timer? I notice the Graff units do that on a roughly 50% duty cycle. It seems you could probably do that to any air blower treatment plant. Link to comment Share on other sites More sharing options...
Ian Posted June 11, 2018 Share Posted June 11, 2018 2 minutes ago, ProDave said: I notice the Graff units do that on a roughly 50% duty cycle. It seems you could probably do that to any air blower treatment plant. We've got a Biopure 1 at a holiday home that only gets used at weekends and we were advised by the manufacturer to operate the air blower on a timer switch 2 hours on/2 hours off. Its been operating about 18 months and seems to be working well so far. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted June 11, 2018 Share Posted June 11, 2018 4 hours ago, ProDave said: Is that done by just turning the pump on and off on a timer? I notice the Graff units do that on a roughly 50% duty cycle. It seems you could probably do that to any air blower treatment plant. I've built a programmable timer that fits inside a standard outdoor single socket (the ones that remains weatherproof with the plug in) and turns the power to that socket on and off with a solid state relay. I've configured this as an extension lead, so although it's wall mounted inside the stone pump enclosure, it's plugged in to one side of a two gang weatherproof socket. I've not yet tested it, but the idea is that the timer can be programmed to turn the pump on and off, with programmable on and off times, both because there are only two of us most of the time (the treatment plant is a Biopure 1) and to reduce the power used by the pump. The selection of the on and off timing is interesting, because @PeterStarck mentioned some time ago that the air ports on his unit (which looked very similar in design to the Biopure, with a conical lower tank section) got blocked with sludge and this may have contributed to his subsequent pump failure. I've been wondering what the best compromise is between on and off times. The 2:1 off to on ratio seems to be one used by other switched systems, and my guess is that the off time needs to be short enough so as to not pose too much risk of sludge settling down too firmly, as it's the air that keeps much of the sludge suspended within the unit, to allow more complete digestion. I did look around to see if there was an affordable and reliable way to sense BOD, as that seemed to be a clever way to select the pump operating duty cycle. If the BOD drops below a certain point than the pump timer could go into the lowest power mode, with the duty cycle changing as the BOD increased in the main tank. Sadly I couldn't find a suitable BOD sensor, nor could I find any information as to whether an analogue measurement (such as measuring gas concentrations in the air above the tank) would reflect the BOD of the tank contents. I do have a PCB master for the timer, it uses an 8 pin microcontroller, simply because as well as switching the SSR on and off, it also sends a signal to the alarm unit, so that the low pressure alarm doesn't operate when the pump turns off during the time cycle. I have to plug a laptop in to change the on and off times, though, as I couldn't be bothered to add external controls for this. The PCB also includes a power supply that runs the alarm unit, and a doppler radar intruder sensor, that triggers our CCTV system to record. The latter is only included because the pump housing is right next to the lower end of the drive, so is ideally positioned to trigger the cameras at the front. 1 Link to comment Share on other sites More sharing options...
joe90 Posted June 11, 2018 Share Posted June 11, 2018 2 hours ago, ProDave said: Is that done by just turning the pump on and off on a timer? I notice the Graff units do that on a roughly 50% duty cycle. It seems you could probably do that to any air blower treatment plant. No, it’s done by adjusting flow of air to various parts, you could see when he was turning it the amount of bubbles and turbulence lessoned. The timer switches from large bubbles ( to break up solids) to fine bubbles ( that generate bio activity). Link to comment Share on other sites More sharing options...
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