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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 (Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic,Din931 Carbon Steel Hex Head Bolt). As a result, several chemical methods have been applied to control P internal loading worldwide (FRP Fiberglass Underground Septic Tank for Effluent Treatment;96 Pin IDC Cable Connector D-SUB Connector SCSI Type;Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Quality Women Leggings Fitness Bra Gym Wear),40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer. 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 (Steel Jacket Steam Insulation Pipeline Production Best Quality;Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting;2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825)) 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 (Aqua Park Equipment Fiberglass Huge Anaconda Water Slide (WS-068)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car;Smelting Furnace Dust Collector Fiberglass Bag Filter;China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop;Electronic Smoke Digitizer Quartz Atomizer Short Quartz Tube;30m3/H Air Flotation Separator for Oil Waste Water Treatment Project;Sell High Quality Food Grade Sodium Carboxymethyl Cellulose CMC;European VDE Schuko 3-Pin Waterproof IP44 Power Plug).with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)(Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress;Professional Fabrication Metal Sheet Mechanical Stamping Machine Parts;W11 Three Rollers Rolling Machine;Professional Double Cup Fully Automatic Coffee Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Waterproof Straight Male Female Sensor Connector), and it has been suggested as a lake restoration measure.
Coagulation-Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)(Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush) and also by water chemistry (pH and alkalinity) (Custom ID Card Holder Soft PVC Plastic Transparent Horizontal and Verticalbusiness Card Holder (14)). 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 (Pc Bar Button Heading Machine). At pH of 6.0-7.Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil(Mill Finish Aluminum Coil Sheet 5052 5005 5754 5083 Price From China Factory,Custom Hardware Lathe Turning Steel Metal Parts High Precision CNC Machinery/Machined/Machining). Algae also can affect coagulation due to characteristics such as morphology, motility,SGS Certificate PE Heat Shrink Film for Beer(Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy,PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material,Baby Bath Sponge Cutting Press).
In the tropical semi-Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use-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.Industrial Series Mbar Low Pressure Gauge with Phenolic Case. 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
Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket, 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(Trenchless Directional Tricone Drill HDD Reamer) and concentrations of total phosphorus (AISI 304 316L 309S 317L 321 904L 421 Stainless Steel Strip;Manganese Metal) 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 (Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132)). 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). UV254HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck(DOM), mainly as humic substances (Licensed Mercedes-Benz Gtr 2 Seats Children Car in Black).
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.)LDPE Plastic Garbage Bags for Construction Wastes, 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 toCreative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Openeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(www.gl-fiber.com).Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow-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 (75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display). 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 UV254Sun Cover Heat Resistance Shade Privacy Screen%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Carboxy Methyl Cellulose (CMC) for Daily Use). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Melamine Block Boardd).
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(Outdoor LED Courtyard Solar Street Lights for Garden Path Road). 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 (Equipment Auto Fire Extinguisher Ball Automatic Fire Extinguisher Ball). 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,Scafold Replacer High Efficiency Spider Lift Articulating Boom, 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 (1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire;China Supplier Good Quality Bending U Bolts Parts;OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag;Ultra-Thin Web Camera Cover Sticker). However,Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa.
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,1500 W /2000 W Disabled Electric Tricycle with Double Seat.Epoxy Resin Impregnated Fiberglass Binding Tape, 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 (Automatic Control Apricot Shell Charcoal Carbonization Kiln Price). In the maximal PAC performance pH was found to be around the neutral (304L 316L Stainless Steel Sheets From Ticso;Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove) which determines the coagulation performance (Advanced Emergency Flame LED Explosion Proof Linear Lamp). 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 (750ml Round Shape Beer Wine Liquor Glass Bottle High Quality).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper.
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