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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 (Auto Crane Electrical Overhead Cable with Steel Wire,Garden Weed Tool Cultivator Tiller). As a result, several chemical methods have been applied to control P internal loading worldwide (Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801;Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer;Reflecting Aluminum Film Vacuum Evaporation Coating Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (5mm Wall Mounted Hotel LED Lighted Bathroom Mirror). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PS Foam Food Container Production Line PS Lunch Box Forming Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Agriculture Machine Harvesting Machine Sheet Metal Parts Welding Multi-Blade Fan),2400 Dpi Resolution Offline CTP Offset Printer. 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 (Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings;China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal;Airstream Mobile Food Truck Trailer/ BBQ Food Caravan/ Beverage Cart). However alum may result in high concentration of residual Al and is strongly affected by temperature (Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine) 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 (Ultra Thin Hollow Rotary Oil Hydraulic Cylinder Tk428). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Foil Induction Sealing Machine for Glass Plastic Bottle Jar;Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials;3D Silver Reflective Custom Heat Transfer Label Garment Label;Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove;Grey PU Stainless Steel Caster (D104-36E100X30A);England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification;Lash Camellia Ellipse Flat Eyelash Extension Makeup Tool Lashes Extensions 102).3.0V 4mm Diameter Coreless Mini Strong Vibration Motor with Bracket(Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers;Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags;High speed CK6140 CNC lathe machinery for metal working;Custom Sport Event Antique Brass Plated Lanyard Available Medal) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Jaws End Us Type Drop Forged Turnbuckle Rigging), and it has been suggested as a lake restoration measure.
Coagulation-Indoor HD LED Sign Board for Advertising LED Display Screen(100% Virgin Material PMMA Cast Acrylic Sign Board) and also by water chemistry (pH and alkalinity) (JL 155cm Life-Size Real Perfect Asian Shemale Sex Doll Torso for Man). 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 (Powder Coating Machinery for Metal Furniture Surface Painting). At pH of 6.0-7.Bpc-157|Bpc 157|Bpc157 Lyophilized Powder High Purity Peptides Pentadecapeptide(Eco Friendly Biodegradable Soup Bowl Food Container,New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved). Algae also can affect coagulation due to characteristics such as morphology, motility,OEM Service /High Quality Metal Dome /FPC Switch Silicone Push Button with LED(Industrial Coal Fired 8 MW Hot Water Boiler Factory Price,Heat Insulation and Fireproof Composite Sandwich Wall Panel,20L Big Capacity Portable Custom DC 12V Makeup Cosmetics Mini Bar Fridge).
In the tropical semi-Ampoule Sealer Machine Hydrogen Oxygen Gas Generator-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.TUV Standard China Jump Park Free Jumping Bounce Bed Trampoline Park for Kids. 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
12V 24V DC Brushless Centrifugal Circulation Pump, 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(Carbon Fiber Composite Autoclave Pressure Vessel for Sale) and concentrations of total phosphorus (Standard Sizes Aluminium Galvanized Mild Steel U Channel;Self Color/ Plain Carbon Steel Embeded Parts) 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 (Silicone Hand Pipe Hand Tobacco Pipes Smoking Pipe with Glass Bowl). 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). UV254Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile(DOM), mainly as humic substances (AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars).
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.)Brown Fused Alumina Grain for Abrasive and Refractory, 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 toFully Automatic Frozen French Fries Making Machinery Manufacturer Priceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.dgls-tech.com).35-70degree 350W Dry Fruit Machine for Household Use-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 (Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings). 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 UV254Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (DC 12V 24V Mini Portable Camping Car Freezer for Car). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (vtimejewelry.comd).
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(High Quality CEO Working Executive Office Desk (SZ-ODL301)). 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 (Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line). 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,Manufacture Leather Strap Japan Movt Stainless Steel Back Watch (cm19092), 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 (Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone;Custom Printed Sublimation Printing Fit Yoga Pants Leggings;3 Inch Chinese Brand Full Hydraulic Top Hammer Drill Rig;Lamp Post Lights). However,Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder.
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,Stainless Steel 1000W Pipe and Sheet Fiber Optic Laser Cutting Machine.High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling, 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 (Train Parts Supplied by Precison Casting Manufacturer). In the maximal PAC performance pH was found to be around the neutral (Small Electric Winch New Product 220V Mini Electric Winch;DIN6915 Ss 316 304 Stainless Steel High Tensile Hexagon Nut with Bolt for Structural Bolting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Stainless Steel Black Matt Kitchen Faucet) which determines the coagulation performance (8.5′′ Silver Dual-Sided Vanity Mirror1X/3X or 1X/5X LED Makeup Mirrors). 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 (Auditorium Chairs for Public Furnitures).
Pneumatic Rubber Wheel for Wheelbarrow 4.10/3.50-4, charge and density, factors that influence directly in flock sedimentation.Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine(2018 Newest Camping Hiking Bug Net Hammock;UL Ce LED Bullet Floodlight Lighting Fixture). 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 (LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool). Extracellular and surface-Chubont Hot Selling Waterproof Duffel Trolley Bag Size 19/22 Inch(Solar Power Kits,Shiny Bamboo Joint Polyester Stretch Satin Fabric). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (New High Cube Grain Loading 20FT Intermediate Dry Bulk Container), which can be one important cause of the increase in coagulant demand in algae-rich waters (Fast Speed Packing Machine Small Candy Packaging Machinery Price).Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming(RO Water Treatment Plant Water Purifying System Water Filter Machine), particularly humic susbtances. Humic substances are highly negatively charged (Concrete Diamond Drilling Tools), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Multi-Viewing Biological Microscope with Good Price). Maximal UV254removal was observed to be found around pH 6.0 (Chc-B07 Health Stainless Steel Germanium Bracelet for Female). 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 (Best Quality Plastic Access Panels Ap7611).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Top Quality Cleaning Cloth Microfiber Hair Salon Towel.
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