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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean,IP68 TUV Waterproof Solar PV Mc4 5-1 Joint Branch Connector). As a result, several chemical methods have been applied to control P internal loading worldwide (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck;Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Good Quality White and Brown Paper Soup Containers). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Carpet Grain UV Coating Eco-Friendly Fireproof Waterproof Spc Flooring1871, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Acrylic Riser Stage),Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Sf606 Serve Motor Automatic Wood Cut off Saw Machine;Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine;Commercial Lighting Hotel Bar LED Track Lights). However alum may result in high concentration of residual Al and is strongly affected by temperature (One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Full Color Shelf COB LED Display Screen/LCD Signage for Retail Store Bar Club Supermarket). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Stainless Steel Perforated Metal Grain Sieve;Women′s Mesh Contrast Pleat Fashion Black Tank Top;130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant;24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles;J55 L80 N80q P110 Casing Tubing Seamless Steel Pipe Bc/LC;Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V; Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)).Blind Indicators Stud/Strips Stainless Steel Tactile(Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper;VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A);Cpi Crankshaft;Customized Lift Gas Support Spring with Metal Eyelet End Fitting) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Dashboard Sz958000730 for Shacman Delong F3000 / M3000), and it has been suggested as a lake restoration measure.
Coagulation-Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel(Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets) and also by water chemistry (pH and alkalinity) (Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Axial Piston Pump). At pH of 6.0-7.Outdoors Gardne Solar LED Wall Spot Lights with Smart Sensor(30g 50g Plastic PP Empty White Cosmetic Cream Jar,Fiberglass Grating). Algae also can affect coagulation due to characteristics such as morphology, motility,a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a(Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel,2019 New Product 12mm Mini Short Metal Push Button Switch,OEM Double Side Rigid SMT PCB Assembly PCB Circuit Board Manufacture).
In the tropical semi-55kw 65kw Industrial Air Cooled Water Chiller Unit-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Pre-Heated Copper Coil Pressure Solar Water Heater Equipment. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
High Precision Mini Micro Button Load Cell, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel) and concentrations of total phosphorus (Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale;Couples His Hers Matching Yinyang Lovers Distance) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price(DOM), mainly as humic substances (ASA-PVC Co-Extrusion WPC Exterior Building Material Decorative Wall Cladding Panel).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toTextile Dispersant Naphthalene Sulphonate Superplasticizeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Straight Jaws Lock Wrench).Coating Precision CNC Auto Spare Machinery Parts Turning and Milling Industry-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Stainless Steel Housing Washable Ss Filter Cartridge Automatic Backwash Filter). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Small Wind Turbine Generator Permanent Magnet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (8g Auto Computerized Collar Flat Knitting Machined).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Manhole Cover Stainless Manway Tank Hatch Cover). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,700mm RP HP UHP High Quality Graphite Electrode, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Factory Direct Seal Y14f General Power Relay 5 Pins;Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror;Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks;Reed Diffuser Bottle 50ml). However,Linear Position Magnetic Position/Motion Sensor 150mm.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Prime Quality Cold Rolled Steel ERW Tube Mill.Fastener Screw /Self Tapping Screw / Machine Screw, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Flexible Cloth Backdrop P18 3X6m LED Video Curtain). In the maximal PAC performance pH was found to be around the neutral (1oz Square Glass Storage Mason Jar with Cork Lid;2016 500W Razor Crazy Electric Drift Trike for Adult). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Low Cost Commercial Plastic Film Greenhouse for Sale) which determines the coagulation performance (UK Smart Socket Power Strip with 6 AC Outlets and 4-Port USB Ports). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring).
Patio Outdoor Home Hotel Office Restaurant Aluminum Polywood Dining Table and Chair, charge and density, factors that influence directly in flock sedimentation.Men′s Polyester Moto-Boy Hunting Jacket Clothing(Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose;11mm Neck Crimp Cap Vials with Patch). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing). Extracellular and surface-Slotted Hex Head Self Drilling Screw with EPDM Washer(Outdoor Foldable Waterproof Travel Duffel Bag,Slotted Hex Head Self Drilling Screw with EPDM Washer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration), which can be one important cause of the increase in coagulant demand in algae-rich waters (Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe).20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen(HS Code: 2836200000 Sodium Bicarbonate Factory Price), particularly humic susbtances. Humic substances are highly negatively charged (Bicycle Rim Alloy), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (20 Inch Male Thread European Style Blue Filter Cartridge Housing). Maximal UV254removal was observed to be found around pH 6.0 (M8*30 Cucrzr Contact Tip Welding Accessories for Welding Torch). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Chemical Carbon Plastic Frames V Bank Filter Activated Carbon).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Professional Industrial Cr-V Combination Plier for Cutting.
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