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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 (Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers,High Quality Round Shape Corrugated Pet Cat Scratcher Board). As a result, several chemical methods have been applied to control P internal loading worldwide (Fasion Style Custom Indian Embroidery Patch;Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor;Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Full Car Key for Chrysler 5+1 Button Remote Control, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Self-Adhesive Paper Roll Thermal Adhesive Label Custom Size Sticker),WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera. 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 (Plastic Reflective Raised Pavement Marker Road Stud;Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style;PU Foam Plastic Squishy Slow Rising Toy for Unicorn). However alum may result in high concentration of residual Al and is strongly affected by temperature (Top Quality Polar Wohlenberg Paper Cutting Blade) 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 (FM-5000b Medical Electric Ophthalmology Eye Ophthalmic Operating Table). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Large Format Auto Open Heat Press with Slide-out Press Bed;Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava;Public Address System High Power Range Outdoor Column Speaker;Automatic Multi Station Nut Forging Machine/Nut Cold Forging Machine;Usps Parcel Sorting Machine;Water-Proof Silicone Coated Fiberglass Cloth;Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace).Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453)(98% Polypeptide Hormones CAS 113-79-1 Argpressin Acetate as Neurotransmitter;Custom Polyester Woven Patch Logo Snapback Hats;Magnetic Push Pins Supplier & Factory;28mm Container Floorboard Plywood Hot Sale Container Parts Good Quality) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)), and it has been suggested as a lake restoration measure.
Coagulation-Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel(Self Tapping Screw Roofing Screw Bimetal Screw) and also by water chemistry (pH and alkalinity) (Double Side Painted Aluminium Coil Plate with PE Film). 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 (New Type of Organic Fertilizer Wet Granulator). At pH of 6.0-7.NEMA IP65 Wall Mount Electric Metal Cabinets(Cation Printing Effect Micro Fleece,2 Head Embroidery Machine Cap Flat T Shirt Embroidery). Algae also can affect coagulation due to characteristics such as morphology, motility,11mm Neck Crimp Cap Vials with Patch, Cap Septem(Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles,Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover,Decking Floor Roll Forming Line).
In the tropical semi-Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)-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.Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts. 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
10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment, 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(Spot Supply Al2O3 85% Bauxite Use for Calcined) and concentrations of total phosphorus (Industrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabric;blue glass bottle with white dropper) 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 (9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion). 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). UV254Solid Surface Grade Grinding Alumina Tyihydrate(DOM), mainly as humic substances (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo).
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.)Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable, 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 toLow Temperature Extended Stem Cryogenic Forged Steel Gate Valveas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.clin-ele.com).Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China-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 (High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping). 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 UV254Desktop Fiber Laser Cutter 1390 Cheap Price 800W/1000W%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Microfiber Sport Towel for Swimming Towel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Manufacturer Stud Capacitor 420V 2700UF High Voltage Aluminum Electrolytic Capacitord).
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(Wg9130583017 Sino Truck Spare Parts Combination Switch). 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 (Fashion Environmental Protection Non-Woven Bag Cotton Shopping 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,LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens, 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 (Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33);Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261;Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data;Servo Packing/Packaging Machine Vp-320s with Volumentric Cups for Powder / Chia / Quinua /). However,Double Station Pesticide HDPE Bottle Making Machine.
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,Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories.Hydraulic Valves-Yuken Series Valve-Flow Control Valve- (one-way) Throttle, 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 (High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off). In the maximal PAC performance pH was found to be around the neutral (Aluminum Height Adjustable Walking Cane (SC-CR58-67);Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)) which determines the coagulation performance (Diamond Glass Drilling Machine). 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 (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131).
High Energy Ejector Venturi Gas Scrubber System, charge and density, factors that influence directly in flock sedimentation.PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence(Home Security Video Door Phone Camera Doorbell Intercom System for Villa;White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem). 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 (Natural Wave Brazilian Virgin Human Hair Extension). Extracellular and surface-6.2mmx6.2mmx4.3mm SMD Waterproof Tact Switch(Security Anti-Counterfeiting Texture Silk Screen Holographic Label,2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD), which can be one important cause of the increase in coagulant demand in algae-rich waters (AAC Block Making Machine Line Supplier/AAC Block Machinery).Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator(Custom Promotional Soft Cover Children Music Book Printing), particularly humic susbtances. Humic substances are highly negatively charged (Tempered Glass Shower Panels with CE / ISO9001 / CCC), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale). Maximal UV254removal was observed to be found around pH 6.0 (Cardboard CO2 100W Tube Tube Laser Cutting Machine). 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 (a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Mimaki SB210 Dye Sublimation Ink for TX400-1800D Inkjet Printer.
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