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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 (Best Price Aluminium Sulphate for Water Treatment,Pellet Calcium Chloride Used For Chemical Desiccant). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board;295L Commercial Horizontal Curved Glass Door Freezer;YAMAHA Ybr125 Carburetor Motorcycle Parts-Oumurs 11950603101). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Souriau Connector Header with Cable). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Saj40-1.2 Safety Device),Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric. 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 Speed Disposable Lunch Box Egg Tray Making Forming Machine;2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet;90W 1750rpm Small AC Single Phase Electric Motor with Capacitor). However alum may result in high concentration of residual Al and is strongly affected by temperature ( USA) 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 (Portable Workshop Gantry Crane). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2kw Solar Hybrid System with Solar Controller MPPT;Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador;Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens;K12 Stainless Steel Hinges inseparable High strength load bearing Hydraulic -damping hinge;Array Junction Box Iron Electrical Switch Combiner Box 16 Strings Solar Box;China Best Tipper Truck of HOWO 4X2 with Lowest Price;Medical Equipment/Dog Oxygen Mask/Nasal Oxygen Mask).Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17(Six Spout Impeller Cement Packing Machine;Competitive Full Color SMD3535 P8 LED Display for Outdoor Commercial Advertising;PA66 Plastic Zip Nylon Cable Tie for Tire Traction;1616 Aluminum LED Strip Channel Surface Mount LED Extrusion) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe), and it has been suggested as a lake restoration measure.
Coagulation-Low Price Promotional Concrete Cement Mortar Plaster Pump Machine(11kv 2000 kVA Oil Immersed Power Distribution Transformer) and also by water chemistry (pH and alkalinity) (Pre-Painted Color Coated Aluminum Coil and Strip). 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 (Huawei Mate X Smartphone). At pH of 6.0-7.18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display(10 Color Lip Liner Easy to Wear Matte Lip Pencil Waterproof Lipsticks Long Lasting Makeup Lipliner,Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M5X8...M5X70). Algae also can affect coagulation due to characteristics such as morphology, motility,34*25cm Office File Pocket Felt A4 Document Bag(Personalized Custom PVC USB Flash Drive for Company Promotional Gift,Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould,Non-Standard Custom).
In the tropical semi-Hex Washer Heaf Self-Drilling Screw with Steel and Rubber Washer-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.Best Quality Square Mini Takoyaki Grill Pan with Helper Handle. 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
Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern, 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(Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)) and concentrations of total phosphorus (Summer Mesh Bulk Ankle Socks Cheap Mens Dress Socks;gjmach-chn.com) 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 (PVC Pipe Extrusion Line CPVC UPVC Drainage Pipe Production Line). 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). UV254High Drying Efficiency Wood Sawdust Dryer for Sale(DOM), mainly as humic substances (Inconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipe).
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.)Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy, 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 toHigh Chrome Cast Iron Ball Forged Steel Ball Grinding Mediaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot Sale Square Shape 40W LED 600X600 Ceiling Panel Light).Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture-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 (Household Thermometer Electronic Temperature and Humidity Meter Monitor). 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 UV254Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (4.5qt Camping Nonstick Wholesale Cast Iron Dutch Oven Bread Pan). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hot Selling PVC Alien H3 Plastic RFID Smart Cardd).
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(9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine). 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 (Twist Lock Power Cord). 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,Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO), 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 (Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod; with Windproof;Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper;Steroids 191AA Gh Huma-Tropin Hormone Human Growth for Bodybuilding). However,Best Price Aluminium Sulphate for Water Treatment.
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,Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630.Sinbeda LCD Display for Sony Xperia Z1 Touch Screen, 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 (Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting). In the maximal PAC performance pH was found to be around the neutral (New Design Hot DIP Galvanized Pig Gestation Stall;High-Class Leather Cover Business Agenda Organizer Planner Notebook). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Strength PVC Foam Board for Building Materials) which determines the coagulation performance (Top Quality Tungsten Cemnted Carbide Solid Slitting Shear Knives Blades Cicular). 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 Foldable Storage Basket with Metal Handle and Lid).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box.
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