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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 (Precision Assembly Jigs Fixtures for Car Outlet,NBR Silicone Rubber Product Rubber O-Ring with High Quality). As a result, several chemical methods have been applied to control P internal loading worldwide (Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine;Recessed Colorful Solar Interaction LED Underground Lighting;Factory Custom Rubber Badge PVC Patches with Male Velcro). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Price Aluminium Sulphate for Water Treatment). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (24 26 30 Inch Large Standing Air Cool Fan Industrial Ventilation Fan Stand Fan),2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster. 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 (Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board;295L Commercial Horizontal Curved Glass Door Freezer;YAMAHA Ybr125 Carburetor Motorcycle Parts-Oumurs 11950603101). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Souriau Connector Header with Cable) 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 (Indoor Appliance Portable Water Air Cooler with 6000CMH). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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; USA;High Quality Paper Pulp Egg Tray Forming Machine;2kw Solar Hybrid System with Solar Controller MPPT;Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador).10.5 Inch Silicone Straws and Stainless Steel Straws, No-BPA Reusable Drinking Straws(Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens;K12 Stainless Steel Hinges inseparable High strength load bearing Hydraulic -damping hinge;Iridescent Clutch Bag;China Best Tipper Truck of HOWO 4X2 with Lowest Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Medical Equipment/Dog Oxygen Mask/Nasal Oxygen Mask), and it has been suggested as a lake restoration measure.
Coagulation-High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine(Six Spout Impeller Cement Packing Machine) and also by water chemistry (pH and alkalinity) (Competitive Full Color SMD3535 P8 LED Display for Outdoor Commercial Advertising). 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 (Produce OEM Electrical Automotive Copper Terminal Connector). At pH of 6.0-7.Woma Acrylic Shower Panel Cubicle Room for Old People (Y698)(1616 Aluminum LED Strip Channel Surface Mount LED Extrusion,ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe). Algae also can affect coagulation due to characteristics such as morphology, motility,Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting(11kv 2000 kVA Oil Immersed Power Distribution Transformer,Pre-Painted Color Coated Aluminum Coil and Strip,Featured).
In the tropical semi-MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration-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.Sf606 Serve Motor Automatic Wood Cut off Saw Machine. 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
Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer, 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(Personalized Custom PVC USB Flash Drive for Company Promotional Gift) and concentrations of total phosphorus (Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould;Grapes Plastic Packaging Bag Supplier & Manufacturer) 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 (Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)). 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). UV254Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)(DOM), mainly as humic substances (Summer Mesh Bulk Ankle Socks Cheap Mens Dress Socks).
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.)Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches, 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 toInconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Herringbone Pattern Agricultural Wheel 6.50-8).Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil-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 (Anti Corrosion Zinc Rich Pure Epoxy Powder Coating). 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 UV25413.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Chrome Cast Iron Ball Forged Steel Ball Grinding Media). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Antique Porcelain Plates Wholesaler Quotes & PriceListd).
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(Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket). 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 (Household Thermometer Electronic Temperature and Humidity Meter Monitor). 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,ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee, 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 (9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine;Twist Lock Power Cord;Hyaluronic Acid Gel Microneedling Device for Meso Serum Mesotherapy Solution;11mm Neck Amber Crimp Top Vial with Cap Septum). However,Farrowing Crate Galvanized Swine Farrowing Crates.
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,Double Sided Tape 1/2 Inch 10 Feet, Transparent Acrylic Double-Sided Tape.Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog, 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 (Indoor HD LED Sign Board for Advertising LED Display Screen). In the maximal PAC performance pH was found to be around the neutral (Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod; with Windproof). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper) which determines the coagulation performance (PA PC PBT Pet Plastic Svmd 3-in-1 Dehumidifying Dryer). 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 (Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker.
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