Alternative Technology Assn Forums

1. 

   Benny
   Member

   Can anyone offer any comments on why a relatively small aerobic septic system would need a 1.5kW blower ? I'm working with a client now and was really surprised to find the motor is so big - and it runs 24h/day. There are many comments online about people trying timers etc but the general recommendation seems to be to run the aeration 24h/d. This is for a facility with 12 residents and 4-5 staff. I can't find any definitive information on the model but it looks like a Biomax C30 and they confirmed that the manual says is uses a 1.5kW blower. Thats 36units per day and $3000 per year !
   Other systems seem to use much smaller blowers round about 80 to 100W.

   I've checked with a power meter and its definitely using 1.5kW too - its not lightly loaded and just idling along.

   Posted Thursday 28 Jan 2016 @ 8:25:20 am from IP #
2. 

   Bushwalker
   Member

   AFAIK the Biomax is a larger scale commercial unit. It uses a bioreactor process.

   How big is this system, and what is the design throughput?

   I agree that normal domestic systems use around 100w blowers. Our recently deceased system had a 150w blower, the new system uses a 50w blower.

   Posted Thursday 28 Jan 2016 @ 9:14:33 am from IP #
3. 

   axess
   Member

   Benny,

   That's 19 people plus visitors and contractors etc. How many sinks,toilets and grease traps would that be?

   Could you install a smarter variable speed blower motor that adjusts to load variations? This is a common practice in industrial motor upgrades.

   Perhaps analogous to fixed air conditioner units that are either flat out or stopped, as opposed to inverter units that ramp the speed up or down according to load.I don't know if this would work with a blower motor though.

   Posted Thursday 28 Jan 2016 @ 8:57:12 pm from IP #
4. 

   axess
   Member

   Furthermore-

   What about multiple smaller units or, retain the existing unit and add a smaller unit similar to the use of an electric outboard for slower,trolling purposes.

   Maybe fit a PV system for offsetting some of the power costs if you have a large roof area. If it's a residential/group accomodation facility then there might be grants available to fund it.

   Posted Thursday 28 Jan 2016 @ 9:03:59 pm from IP #
5. 

   Bushwalker
   Member

   I agree it could be best to offset the blower consumption with PV.

   If the air pump for the system is pulling 1.5kW it is a serious air pump, probably something like this:

   http://www.wastewaterequipment.com.au/products/Becker-SV8-160-2-01-3-Phase--1-5KW-

   Maximum Flow: 75m3/hr = 1250 Litres per minute

   Your standard domestic wastewater plant probably has something like this:

   http://www.wastewaterequipment.com.au/products/Hiblow-HP100-Air-Blower

   Air Flow: 100 litre per minute

   Without seeing the plant in question, I can only suggest that the air requirements are far above that of a domestic system. If you replaced the existing pump with the low power units, you'd need at least a dozen of the domestic units to match the supply.

   Posted Thursday 28 Jan 2016 @ 10:11:31 pm from IP #
6. 

   Benny
   Member

   Thanks for the replies.
   We can't find out exactly what the system is so far. The servicing agents just service it and didn't install it. But as I said it does look very like the Biomax C30 pictures and given that their manual says the C30 uses a 1.5kW air pump I suspect thats what it is.
   If you look at the info' on their website the C30 is designed for 18 people in an accommodation environment and up to 5400L/day processing.
   We are considering solar for the whole site but for now just want to find out why this blower seems so big. If a domestic system (designed for say 4 people?) uses 100W why does a system for 18 people use 15x more power ? Not the old cubed law is it ?
   I checked at a nursery where I volunteer and they have a similar system We have up to 30 people there every day using toilets - no washing machines and not there all day of course, but this system is using an 86W blower.
   We're not going to try timers or different sized motors without some pretty good idea that all will still work OK.
   I'll try to find more info' on other suppliers "commercial" systems.

   Posted Thursday 28 Jan 2016 @ 11:47:42 pm from IP #
7. 

   Bushwalker
   Member

   Looking at the Biomax website, it would appear that the plant naming refers to the number of tanks, they all seem to be the same size tanks. I'm guessing about 3m high by 2m wide. So, I think that makes the tank about 9000L?

   

   The C30 has 3 tanks, the C80 has eight tanks. If my volume calculations are correct and your guess is the system is a C30, your C30 has around 27,000L to aerate.

   Compared to an Envirocycle 10NR (10 person domestic) and assuming both systems are similarly filled, then the C30 has about triple the capacity. Maybe this commercial system has a larger capacity overhead than a domestic system.

   Posted Friday 29 Jan 2016 @ 12:40:00 am from IP #

RSS feed for this topic