Biosolids dewatering using super absorbent polymers (SAPs) Mostafa M.Noureldin Illinois Institute of Technology

Biosolids dewatering using super absorbent polymers (SAPs) Mostafa M.Noureldin Illinois Institute of Technology

Overview Super absorbent polymers (SAP) Biosolids management concerns Approach Results SAP removes water from biosolids SAP is recycled Conclusions Future work

Super absorbent polymers SAP Hydrogels Retain large water volume Add little mass Many applications Agriculture Diapers Wire water blocking

Biosolids management There s s too much water Hinders process efficiency Removal is energy intensive Biosolids management is expensive Hypothesis: An SAP-based dewatering process can be cost effective

Lab work Concept Water recovery Biosolids SAP SAP Reuse

Experimental work 1. Milorganite: Biosolids by-product 5% N 4% Fe 2% P 2 O 5 1.2% Ca 2.Tea filter 3. SAP

Preparing surrogate biosolids Milorganite reconstitution Volume = 500 ml Temperature range = 22-25 25 C Electric blender Solid content % 5 10 15 20 g 25 50 75 100

Water absorption is rapid 100 Original % solids 5% Pure Water Water captured, g 75 50 25 10% 15% 20% SAP dose is 0.5 gram 0 0 5 10 15 20 Time, min

Water uptake increases with SAP dose 12 SAP dose, g 0.5 1.5 Solid content, % 10 8 2.5 Double 6 5 4 0 5 10 15 20 Time, min

Milorganite versus real biosolids? Overnight mixing improves hydration Yields more realistic slurry

Solids preparation affects water removal 12 SAP dose = 2.5 g 11 10 Solid content, % 9 8 7 6 5 4 Alternate preparation method 0 5 10 15 20 Time, min

Surrogate vs. Real biosolids sample 8 7 Milorganite Digested sample Solid content, % 6 5 4 3 0 5 10 15 20 Time, min

SAP regeneration Regeneration through: 1. ph control 2. Temperature control 3. Electrolysis Test is conducted on Pure Water

Regeneration rate decreases over time 80 Pure Water 70 % Water recovery 60 50 40 30 20 Applied potential (v) 5 10 0 0 20 40 60 80 100 120 Time, min

Regeneration rate increases with potential 80 Pure Water 70 % Water recovery 60 50 40 30 20 Applied potential (v) 5 10 10 0 0 20 40 60 80 100 120 Time, min

Regeneration rate increases with potential 80 Pure Water 70 % Water recovery 60 50 40 30 20 10 Applied potential (v) 5 10 15 0 0 20 40 60 80 100 120 Time, min

Regeneration rate increases with potential 80 Pure Water 70 % Water recovery 60 50 40 30 20 Applied potential (v) 5 10 10 15 20 0 0 20 40 60 80 100 120 Time, min

Performance decreases with increasing cycles 0 Time, min to collect 50 ml of water 10 20 30 40 50 60 Biosolids could improve cycling performance Pure water leaches ions from SAP 70 1 3 5 7 9 11 13 15 17 Cycles

Dewatering is rapid Conclusions Solids concentration is increased at least 50% SAP can be regenerated Biosolids characteristics affect performance

Suggested applications Pre-treatment Blending Storage Conditioning Thickening Gravity belt Rotary drum Digestion Aerobic Anaerobic Lime stabilization Dewatering Centrifuge Filter press Drying beds Biosolids Thanks Disposal Drying Direct drying Storage

Future work Continue with real biosolids test Bench scale design Membrane BIOSOLIDS SAP Thicker biosolids Continuous contacting design Water recovery SAP Reuse $avings

Future work Assess the possibility of reducing non- reusable polymers before dewatering Analysis of different parameters Membrane selection procedure Particle size distribution Surface charge

Questions?

Project Team Professor Paul Anderson (EnvE( EnvE) Professor Fouad Teymour (ChBE( ChBE) Enve MS student (Mostafa M. Noureldin)

Extra aiding data

SAP-based biosolids dewatering concept Efficient management Wet biosolids Dry biosolids Water recovery Dry SAP Wet SAP SAP recycle

Lab work Concept Water recovery SAP Reuse

Water distribution in biosolids: Intracellular water Colloidal water Free Water (75%) Depending Capillary water 95 % of biosolids is water

Water management in WWTP Wastewater influent Discharge Screens Grit Chamber Primary clarifier Aeration tank Secondary clarifier Conventional WWTP Return activated sludge Biosolids treatment and disposal Disinfection

Test

SAP types and preparation processes Wide variety depending on: 1.Chemistry 2.Cross linking Core Surface 3.Manufacture Starch, cellulose, polyvinyl, and polyethylene Polyacrylicacid Preneutralization Postneutralization

Expanding Beyond Simple Dewatering

Ionic Partitioning Some ionic species can be preferentially enriched in the absorbed hydrogel This can be controlled by proper design of the hydrogel functionality Possible by-products of value in aqueous recovery stream, e.g. Liquid fertilizer,

Directed Polymer Synthesis Controlled crosslink density leads to control over absorption/desorption rate and capacity. Design of functionality (Sulfonic( vs. carboxylic acids) can enhance the osmotic pressure of the hydrogel and thus the rate of absorption. Design of functionality (acid vs. base) can be used to target specific ion separation