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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 (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory,Aluzinc Roofing Sheet). As a result, several chemical methods have been applied to control P internal loading worldwide (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B);China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China;Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (LG936 LG938 Front End Loader Parts Gas Spring 29330011391). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ouwave HVAC Scent Fragrance Systems Aroma Diffuser Electric Scent Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Us American Flag PRO Elite Sports Compression Arm Sleeve),Interlocking Foam XPE Gym Mats in Martial Arts. 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 (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump;360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest;Plastic Casement Window). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet) 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 (Constant Humidity Curing Cabinet Wholesaler Quotes & PriceList). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D;Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring; IPS 720*1520 Display Android 9.0;Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley;Window Display 4s Shop Ornaments Shopping Mall Dp Point Games Jump Props Decoration;Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket;Wholesale Promotional Children Painting Apron).Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood(Poultry Farming Automatic Chicken Feeding Pan System;600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine;20Blade 58cc Gas Chain Saw Wood Cutter Gasoline Chain Saw Heavy Duty Electric Chainsaw;Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Concrete Paving Interlocking Block Brick Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Absorbent PP Mat Hardwearing Doormat with Round Shape(OEM Custom Cotton Twill Flat Top Military Army Hat and Cap) and also by water chemistry (pH and alkalinity) (Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture). 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 (Fingerprint Password Digital Office Private Deposit Boxes Luxury Safe). At pH of 6.0-7.New Business Projects Mobile 5D Cinema with High Quality(Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale,Fish Scale Shaped Waterproof Roof Tile for Roof Tile). Algae also can affect coagulation due to characteristics such as morphology, motility,Zumex Style Speed Tank Podium Commercial Citrus Juicer(Hydraulic Control Valve-100A Angular Stable Water Level Valve,Direct Thermal Label with Premium Quality Adhesive Sticker Label,Plastic Sheet Roofing).
In the tropical semi-High Quality Galvanized Pan Head Self Drilling Screw-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.Bct-01 Hospital Furniture ABS Medical Emergency Treatment Trolley Cart. 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
Co-Extrusion Extruder Single Screw Auxiliary, 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(Agricultural Low Cost Greenhouse Farming Equipment) and concentrations of total phosphorus (Anti-Slip Crazy christmas Cute Funky Cotton Custom Socks;T5 T8 T10 Led Tube Lighting) 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 (Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04)). 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). UV2545 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe(DOM), mainly as humic substances (Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller).
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.)Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks, 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 toBamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stickas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Tractor Hydraulic Cylinders).Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth-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 (OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels). 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 UV254Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Foldable Magnetic Closure Paper Packaging Boxesd).
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(Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor). 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 (Seu 2*8 AWG Concentric Service Entrance Cable). 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,Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube, 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 Electric Car Step Siliding Step with Ce Load 250kg;China Manufacturer Cement Plaster Storage Pressure Tank Container;China Automatic Round Stainless Steel Bar Peeling Lathe Machine;Actuator Butterfly Valve). However,Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts.
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,Outdoor Food Meal Heating Bag for Travelling and Camping.60 Ton Track Material Handling Excavator for Sale, 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 (Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring). In the maximal PAC performance pH was found to be around the neutral (Activated Carbon Pellet Manufacturer Used for Gas Treatment;Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Auto Starter 0001230002 12V 3.0kw 11t for John Deere) which determines the coagulation performance (China Famous High Quality Carbon Filter & Apparatus). 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 (Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table).
Pig Breeding Equipment From China Direct Factory, charge and density, factors that influence directly in flock sedimentation.Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock(New Product High Quality Home Smart Wireless Video Doorbell Camera;Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier). 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 (1kVA/2kVA/3kVA/4kVA/6kVA/8kVA/10kVA/15kVA/20kVA/30kVA Single Phase Online UPS). Extracellular and surface-High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle(Blank Polo Shirts,12oz Dispossable Ripple Wall Paper Cup with Good Insulation). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Naked Mango Premium E-Liquid for Electric Cigarette), which can be one important cause of the increase in coagulant demand in algae-rich waters (M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter).Finisher Kids Antique Sundown Marathon Sport Medal (071)(Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM), particularly humic susbtances. Humic substances are highly negatively charged (Mica Tape), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag). Maximal UV254removal was observed to be found around pH 6.0 (Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag). 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 (Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ce High Quality Stylish SMD LED Flood Light 10W 20W 30W 50W 100W 150W 200W.
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