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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 (High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05,1.67 Blue Cut lens Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (Preparation Concrete Vibrator Shaft with Japanese Coupling;500ml Stainless Steel Insulated Double Wall Vacuum Drinking Bottle (SL-550);Textile Waterproof Motorcycle Trousers for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Non-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Bracelet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Arrival Household Self-Washed Flat Mops Cleaning, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hot Rolled High Strength Concrete Pump Wear Plate),New Type Portable 380V Electric Winch in Stock. 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 ( 316 Slot Stainless Steel Tube with Glass;Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery;Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains). However alum may result in high concentration of residual Al and is strongly affected by temperature (Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve) 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 (Copper Hairline Satin Finished Stainless Steel Decorative Sheet Plate). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (FM200 Automatic Fire Suppression System for Electrical Room;Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches;China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph;Automatic Monochrome Crystal Shoe Injection Molding Machine;Small Egg Tray Mach;Portable Adjustable Basketball Hoop for Teenager;Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal).10ml Portable Spray Perfume Glass Empty Bottle Atomizer(Ferrite Magnet Used in Motor as Magnetic Strip;Three Lines Production Three Side Seal Pouch Making Machine;Copper Coil;Cement Roofing Sheets Pigment Yellow Iron Oxide Prices) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Oversized Canvas Travel Tote Luggage Weekend Duffel Bag), and it has been suggested as a lake restoration measure.
Coagulation-Ce Approved Acrylic Mini LED Letters Sign for Outdoor(Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device) and also by water chemistry (pH and alkalinity) (Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb). 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 (X-ray Shielding Automatic Sliding Lead Motorised Door). At pH of 6.0-7.Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner(New Design Customized Juice Beverage Canning Machine,EPS Sandwich Panel Forming Machine Production Line with High Quality). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Quality Hydroponic Film Greenhouse Steel Structure Construction(PCBA Indutrial Control Assmebly Quick Turn PCB Assembly,Garden Metal Natural Rusty Flower Decoration Product,Fashion Studs Genuine Real Leather Messenger Bag Women Handbag).
In the tropical semi-Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line-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.High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1). 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
Small Playground Plastic Slide Preschool Equipment Toys for Kids, 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(China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light) and concentrations of total phosphorus (2 Storey Worker Living Block Container House Supplier;High Quality 12 Strand UHMWPE Polyester Covered Offshore Rope/Nylon /PP /Polyester Marine Mooring Rope) 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 (Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump). 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). UV254Wholesale Events 6FT Wood Dining Round Table(DOM), mainly as humic substances (Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets).
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.)Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel, 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 toCustom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holderas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Tile / Stone Adheisves Drybond Mortar Additive Thickener HPMC).Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould-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 (Popular Selling Sausage Casing Making Machine). 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 UV254Ce Certificated Acm-60 PTFE Powder Grinding Mill%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (air freight China to Botswana Gaborone logistics express courier services). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Factory Direct Sale Hydraulic Cylinder Seal Kit with Many Modelsd).
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(Good Sale Lfc Sand Preparation and Casting Molding Line). 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 (Vegetable Herb Garden Hand Tools with Storage Box). 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,Automatic Magnetic Induction Heater for Band Saw Quenching Production System, 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 (Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler;Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant;New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale;Aluminum Foil Food Container With Plastic Lid). However,Original Germany Bitzer Brand Compressor 4hc-1.2y.
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,Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop.Customized CNC Machining Checking Fixture for Automotive Bracket, 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 (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope). In the maximal PAC performance pH was found to be around the neutral (High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices;Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Tungsten Solid Carbide Straight 4/6 Flutes Reamer) which determines the coagulation performance (Upvc Roofing Sheet Foshan). 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 Industrial Field Block Ferrite Rare Earth Magnet).
High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices, charge and density, factors that influence directly in flock sedimentation.Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet(7;Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting). 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 (Stainless Steel Axle Shaft). Extracellular and surface-1.2V 3600mAh 4/3A size rechargeable NiMH Battery(Car Fuse Terminal Block Suppliers for Sale,Suitcase Belts Continuous Dyeing and Finishing Machines). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch), which can be one important cause of the increase in coagulant demand in algae-rich waters (Caterpillar 420f Backhoe Laoder 2015 Year Japan Made).2019 New Designed High Quality Playground Indoor Kids′ Plastic Slide(Stainless Steel Slot Screen Pipe 0.3mm Slot Size), particularly humic susbtances. Humic substances are highly negatively charged (Cerveceria Stainless Wine Tanks for Sale 1000L Wine Fermenter), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty). Maximal UV254removal was observed to be found around pH 6.0 (2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)). 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 (220kv Composite Suspension Insulators for Transmission and Distribution Line).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Electric Multifunction Motorized Lifting and Rotated Medical Equipment Product Fth-005.
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