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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 (Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging,Luxury 100% Cotton Autism Anxiety Weighted Blanket Adult). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting;Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar;Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Kw-700 Industrial Commerical Driving Type Floor Scrubber Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hollywood Makeup Mirror),Industrial Series Mbar Low Pressure Gauge with Phenolic Case. 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 (Lifting and Hoisting Industrial Manual Chain Lever Block Vt;Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set;Quality FTTX Maintenance Tools Effective Fusion Splicers). However alum may result in high concentration of residual Al and is strongly affected by temperature (Stainless Steel Brass Spring Check Valve (VG12.90081)) 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 (Noodles Instant). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( Plastic Molding;USA American and Canada 110V UL NEMA 5-15 Power Extension Cord;Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture;30cm Round Clear Plastic Pot Plant Trolley;Home Ozone Appliance;Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home);Original Monitor Display Panel for Cat320d Excavator).Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket(China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Sdlg B877f Backhoe Loader Price;Soda Ash Light;Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts), and it has been suggested as a lake restoration measure.
Coagulation-HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck(60 Grit Mini Abrasive Flap Disc for Carbon Steels) and also by water chemistry (pH and alkalinity) (High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals). 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 (Steel H Beam Structure Workshop (Q345B/Q235B)). At pH of 6.0-7.LDPE Plastic Garbage Bags for Construction Wastes(Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine,Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525). Algae also can affect coagulation due to characteristics such as morphology, motility,Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow(Micro Water Tank Level Transducer for Wall Hung Gas Boiler,High Temperature Alternative Stainless Steel Band in Different Package,www.asiamzsteel.com).
In the tropical semi-Sun Cover Heat Resistance Shade Privacy Screen-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.Scafold Replacer High Efficiency Spider Lift Articulating Boom. 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
Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa, 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(New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges) and concentrations of total phosphorus (Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Ball Valve Dn50) 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 (700mm RP HP UHP High Quality Graphite Electrode). 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). UV2541500 W /2000 W Disabled Electric Tricycle with Double Seat(DOM), mainly as humic substances (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch).
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.)Epoxy Resin Impregnated Fiberglass Binding Tape, 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 toMini Cheap Shower Cap for Hotel House Hospital SPA Restaurantas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Options).Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty-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 (New Mini Loader Radlader Mini Zl936 Wheel Loader). 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 UV2542019 China Professional PE/PP Knotless Net Extrusion Line Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Quality Compair Air Compressor Air Filter 50273). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Window Gap Silicone Seal Stripd).
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(Professional Supplier of Hot Rolled Steel U Channel). 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 (Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop). 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,Certified 100% Natural & Pure Organic Basil Herbs Oil, 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 (Auto Part PDC Parking Sensor for BMW 66209261595;Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank;Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush;Curing Rack). However,12oz Dispossable Ripple Wall Paper Cup with Good Insulation.
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,6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper.Construction Structure Steel Shot Blasting Cleaning Machine, 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 (Kfc Macdonald Food Grade Convenient Disposable PE Glove). In the maximal PAC performance pH was found to be around the neutral (IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor;Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose) which determines the coagulation performance (3d Floor Sticker). 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 (Custom Aluminum Steel CNC Machining Mechanical Turning Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8).
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