Dryden Aqua AFM active filter media and mechanical filtration systems

AFM active filter media
replaces sand & activated carbon

AFM in Tertiary WWT .....Power point presentation click here
Reports & Schematics	Pressure Filters for AFM	RGF system	Skid mounted system	AFM removes List 1 chemicals	Activated Sludge


Tertiary treatment of sewage effluent, the performance of AFM against different systems

TYPE OF FILTER	Suspended solids			Turbidity ntu			fecal bacteria /100ml			water velocity
TYPE OF FILTER	inlet mg/l	outlet mg/l	Performance %	inlet	outlet	Performance %	inlet	outlet	Performance %	m3/m2/h
RGF sand filter with sand	7.14	2.2	69%	3.5	2.23	36%	23120	12300	46%	1.2
Pressure filter with sand	8.18	3.82	53%	5.87	4.76	18%	22311	18023	19%	4.96
Moving bed sand filter with sand	7.08	3.82	46%	2.13	1.79	16%	14067	10307	26%	5.4
Drum filter 10 micron	14.66	7.33	50%	7.16	3.88	45%	56712	38460	32%	3.23
Disc Filter 10 micron	5.6	3.1	44%	2.22	2.06	7%	30450	21138	30%	2.12
Ring Filter 10 micron	7.41	3.98	46%	3.01	3.17		9447	7761	17%	2.5
AFM Pressure filter	10.60	0.89	96%	2.98	0.24	92 %	23000	10000	58 %	3.59

NOTE : The results are from a report published in the Spanish magazine " Technology del Agua" in December 2009, page 47. The AFM results correspond to a test made at a water treatment works by and independent water company in a working effluent plant near Valencia the 11/12/2009. The test bed is shown on the right. click here to down load a copy in Spanish

Under normal operating conditions if sand is used for the treatment of sewerage effluent, the sand will rapidly become colonized and blocked by bacteria. However the micro structure, catalytic activity and high negative zeta potential of AFM make it self sterilize. AFM will not biofoul or coagulate, so it is the perfect media to use in standard pressure filters or rapid gravity for the treatment of wastewater. A simple pressure sand filter with AFM will out-perform a moving bed filter of any deep bed sand filter by a factor of 2 or 3 times, and it is 1/10th of the cost.

The performance achieved is almost as good if not better than membrane systems. AFM will remove solids from the water down to approximately 5 microns. AFM will also remove even smaller particles and adsorb organic molecules by surface adsorption. When used in combination with our resonating ZPM unit for mechanical coagulation the performance is even better. In addition, membranes result in the development of high concentrations of phosphates, which can cause major problems.

Operational criteria

The loading on AFM for tertiary treatment of sewage is very high as such water flow rate of no more than 10 cubm/hr per square meter of filter bed surface area. Back-flush frequency normally ranges from 3 to 24 hours, back-flush flow rate is 50 cubic metres per hour per square meter of filter bed surface area for 2 to 5 minutes. The back-flush water is directed back to the beginning of the works. Air purging of the bed prior to back-flushing will reduce the amount of back-flush water, air purge rate is 50 to 100m/hr

Performance benefits.... typical 90% removal

The graph presents the results from a sewage works showing the suspended solids level in the discharge from the percolating filters. The water then enters the humus tanks, and the water quality results for the works discharge from the humus tanks is presented. The AFM filter receives its water directly from the percolating filters ( AFM influent) but before the humus tanks. The AFM effluent data gives an average value of approximately 7mg/l from an influent of around 70mg/l. 90% solids removal efficiency is achieved. The data is the same as the results presented in the above Table.