Am monitoring Water Treatment Works with capacity of 17 ML/D and all along the turbidity was <5 NTU for final effluent during dry weather season, with incoming turbidity of 500 - 800 NTU.
And now in summer the turbidity for final effluent is 50 - 60 NTU with the inffluent of 1200 - 2000 NTU of untreated. The flocculants that are usual use is Poly-electro.
The incoming flow is gravitate in all season, there is no usage of electricity to abstract water from the catchment.
My question was:
Which flocculant is good in summer and which one is good in winter?
To produce good water quality in all season which area must i focused on it.
Consider using Alum because it is very good with high turbidity and also paired with a number of Coagulant Aids or polymer that may increase floc size and also improve sedimentation
Jar test with different combinations of flocculant and coagulant is the best solution. The quality of Raw water will also play a major role in this subject. So please first check the Influent quality and do Jar Testing.
Alum is best, but experience is that water temperature is one of most prominent issue regarding dealing Turbidity, you get good results if concentrate with temperature at any season (winter or Sumer), coagulation or Fluccolation main depends on temp
Hello Phetla, as Gary Brown has said, it is useful to conduct jar tests with a range of poly-electrolytes. It may also help to carry out a zeta potential assessment to help narrow down the type of poly-electrolytes that could be tested. In many cases the suppliers of the poly-electrolytes will do these tests for you or at least advise which ones would be most likely to meet your operational requirements.
However before you do that, try to understand what is happening at the water source during the summer period - is it related to rainfall events or to temperature increases, and is there a possibility that you are experiencing algal growth in the water source - this will need another approach to address the algae before coagulation, or alternatively to modify your treatment process to incorporate a flotation clarification unit. This is likely if there is nutrient enrichment from agriculture or wastewater treatment works upstream of your source.
Best wishes - you may want to contact Lepelle Water who also have a number of treatment works in your part of South Africa.
Hi Phetla, I suggest you do some onsite flocculation test to optimise coagulation and flocculation with different dosages of coagulants and flocculants while also adjusting pH to determine optimum dosages. A plant of this size should have the required equipment. If you do not have the equipment ask a chemical supplier to do the tests for you. Trust you get this sorted,
I would consider using a coagulant like aluminium sulphate (alum) for such a high turbidity. You could continue to use the polyelectrolyte to enhance the performance of the alum.
I would consider using a coagulant like aluminium sulphate (alum) for such a high turbidity. You could continue to use the polyelectrolyte to enhance the performance of the alum.
Please contact me to discuss issue of Polymers and treatment methodology. jerry@clearflowgroup.com I have questions regarding Process flow and influent. Clearflow has developed and Patented a Gel Flocculant technology which requires zero electricity or power to treat . The Gel product is self dosing and used in all forms of waste streams from mining to municipal applications as we have multiple formulations. We use these products along with other forms of Patented Treated Water Polishing Curtain technology to meet the requirements you are looking for. All of our products are environmentally friendly and fish safe. We distribute world wide and have manufacturing in both Canada and the US. I have attached a couple brochures regarding some of our products mentioned. I look forward to your email reply.
I should also note that Clearflow's Gel Flocculants are not pH sensitive between 3 pH and 12 pH, not temperature sensitive between freezing to boiling and are not salt/chloride sensitive up to aprox 250,000 mg/l (ppm) . The Gel Product also has a high affinity to metals and charged particles including organics such as algae. and nutrients such as phosphorus. These unique features allow the products to work in a wide variety of contaminated waters. Additionally NTU reductions are seen typically in the 90% to 98% range.
Hi there, firstly have you adjusted the applied dosage between seasons and/or have you optimised dosage by conducting jar tests? You may need to change your poly for the two different seasons and you may need to consider pH adjustments, this can all be concluded with jar testing
pre-settling dams that double as raw water storage can sometimes help with reducing the sharp increases in NTU, if you have the space
does your treated water demand change between seasons? You may need to adjust for this as well