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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 (New Design Artificial Leather Fabric PVC Leather for Furniture (1008#),Wafer Type Cast Iron Butterfly Valve Manufacturer). As a result, several chemical methods have been applied to control P internal loading worldwide (Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning;Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275;Blackboard Imprint Unique Glass Drinking Jars for Canning). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Anti-Wrinkle Eye Cream Six Peptide Anti-Aging Serum Black Circle Cleaner),Paint Spray Booth Air Flow Vehicle Paint Booth for Sale. 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 (High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic;Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Custom Design China Plastic Injection Molding Factory) 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 (Acidulants High Purity Acidity Regulators Sodium Citrate). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Pre-Heated Copper Coil Pressure Solar Water Heater Equipment;Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale;Hot Selling SAA Rcm Listed CCT Changeable LED Down Light;Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades;Black Stainless Island Range Hood;Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle;20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen).High Purity Calcined Alumina Micro Powder for Ceramics Refractories(Manufacturers Supply Through Hole Right Angle USB 1394 Connectors;Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo;Smart Board Interactive Blackboard;Factory Directly Sale Virgin Kraft Liner Paper Machines) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Special Offer Stock Primary School Uniform Shirt for Boys), and it has been suggested as a lake restoration measure.
Coagulation-Customized Dummy Animal Teething Toy Design Baby Pacifer(12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery) and also by water chemistry (pH and alkalinity) (Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult). 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 (Portable LED Display Interactive Module Laser Sensor Smart Interact Whiteboard for Student). At pH of 6.0-7.Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings(Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts,Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer). Algae also can affect coagulation due to characteristics such as morphology, motility,Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches(Aol CNC 1625 Cutting Plotter for Corrugated Cardboard,Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock,Elegant and Comfortable Design Ideal Dining Chair).
In the tropical semi-Automatic Concrete Paving Interlocking Block Brick Making Machine-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.Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows. 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
Plastic Injection Moulding for Plastic Car Toys Products, Truck Parts, 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 Model Solar Room Lighting System Lighting Kit Light in Remote Area) and concentrations of total phosphorus (Lacquered PVC High Intensity and Good Elastibity Tarpaulin;/Rotary Device Cnc Wood Router Price) 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 (with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)). 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). UV254Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valve(DOM), mainly as humic substances (Food Cardboard Paper Packing Box for Pastry).
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.)GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine, 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 toBaby Teething Toy Wooden Bunny Round Ring Teetheras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Qt40c-1 High Quality Bullet Cube Ice Block Machine).Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine-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 (Hot Sale 99% Powder Form CAS 70288-86-7 Ivermectin with Best Price). 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 UV254Samsung 46 49 55 LCD video wall Samsung LCD screen%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Arrival Sports Anti UV Protective Arm Sleeves). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Starch Separation Decanterd).
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 Leather Wristband USB Disk 4GB to 32GB). 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 (Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag). 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,Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal, 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 (7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing;Textile Machine Parts Multiple Pattern Box;Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker;Aluminum Led Heat Sink Profile). However,AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars.
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,250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups.Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072, 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 (Accept Customization Perfume Direct with Good Price). In the maximal PAC performance pH was found to be around the neutral (AAC Autoclaved Aerated Concrete Brick Making Machine;Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette) which determines the coagulation performance (Modern Industrial Restaurant Furniture Turner Vintage Toledo Counter Bar Stools). 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 (FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound).
Professional Super-Automatic Tyre Changer Without Lever, charge and density, factors that influence directly in flock sedimentation.Non Alkali Glassfiber Yarn for Weaving Electric Cable(Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair;2400 Dpi Resolution Offline CTP Offset Printer). 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 (Trailer Part Coupling). Extracellular and surface-Outdoor Decoration Small Music Dancing Garden Water Feature Fountain(Offline Backup Time UPS 500-3000VA,Small MOQ Food Grade Glass Bottle Wine Cork Stopper). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Quality Precision Plastic Mold/Mould Insert), which can be one important cause of the increase in coagulant demand in algae-rich waters (Alternator for Toyota 91).Indoor or Outdoor Power Distribution Equipment Metal Box(Guard Rail Roll Forming Machine 2.0-4.0mm Thickness), particularly humic susbtances. Humic substances are highly negatively charged (3s 11.1v 1800mah 25c), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (China Genuine Leather White Color Safety Shoes). Maximal UV254removal was observed to be found around pH 6.0 (HS20-600 Shipping Lifting Device Customized Hydraulic Station). 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 (China Supplier Customized Polish Storage Wall Mounted Wine Rack).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps.
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