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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 (100% Cotton Heavy Duty Workwear Wholesale Work Clothes,Beverage Drink Coffee Vending Machine with LCD Advertising Screen). As a result, several chemical methods have been applied to control P internal loading worldwide (High Speed Aluminum Alloy + ABS Shell Video Type-C to HDMI Cable;Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material;24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Portable Silicone Food Fresh-Keeping Kitchen Storage Freezer Bag). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Transparent/Vegetable/Hollow/Halal/HPMC/Pullulan/Empty Capsule),PVC Gas Hose, LPG Hose Best Choice for Home Use. 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 (Drainage Rubber Grasss Ground Stabilisation and Play Area Anti Slip Rubber Mat;Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood;High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing). However alum may result in high concentration of residual Al and is strongly affected by temperature (IP65 Waterproof Metal Distribution Box and Power Metal Box) 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 (Hermetic Package For Optoelectronic Components). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable;Masturbators Adult Sex Toys Japanese Love Doll;Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System;Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer;Auto/Truck Filter Paper;Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen;172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)).Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan(4 Drawer Steel Office Vertical Filing Cabinet;Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy;Alcoholic Beverage Glass Bottle;CO2 Gas Shielded Stainless Steel Welding Wire (ER308L)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner), and it has been suggested as a lake restoration measure.
Coagulation-Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress(Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden) and also by water chemistry (pH and alkalinity) (Plastic Round Home Storage Box Vacuum Insulated Lunch Box). 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 (Motorcycle Repair Parts Aluminum Engine Speed Throttle Handlebar Grip). At pH of 6.0-7.Best Polystyrene Sandwich Board Manufacturer(Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting,Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge). Algae also can affect coagulation due to characteristics such as morphology, motility,Outdoor WPC Wood Plastic Composite Fence Board with High Quality(High Precision Customized Medical Injection Mold for Needle Holder,Customized Mining Equipment with Drawing Design,Traditional Desk Lamp).
In the tropical semi-Full Automatic Chocolate Holding Tank with Water Jacket-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.Professional Supplier of Hot Rolled Steel U Channel. 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
22mm 2no2nc Metal on off Start Button Power Push Button Switch, 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(Sublimation Coated Aluminum Sheets for Heat Transfer Printing) and concentrations of total phosphorus (Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top;Cotton Laundry Bag) 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 (GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine). 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). UV254Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack(DOM), mainly as humic substances (Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture).
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.)Beauty Equipment Face Lifting Hifu Equipment, 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 toCross-Border Jewelry Hot Silver Set Diamond Full Diamond Crownas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Liquid Nitrogen Generator China).Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008)-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 ( Restaurant Kitchen Used Lift). 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 UV254LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (All White Shoesd).
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(Beautiful Design Coral Fleece Terry Towel Set). 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 (Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber). 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,19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU, 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 (Filter Fiber Car Engine Cabin Air Filter for Mazda; Customized Available;Vulcanized Fiber Paper Electrical Insulation Paper;Davis Water Treatment). However,Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag.
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,Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug.Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel, 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 (2019 Wholesale 6.5HP 300kgs Mini Dumper Crawler for Agriculture). In the maximal PAC performance pH was found to be around the neutral (on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000);Double Station Pesticide HDPE Bottle Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels) which determines the coagulation performance (Disposable Non Woven Airline Pillow Case Hotel Pillow Case). 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 (Steel Fabrication Part Custom Steel Sheet Metal Fabrication Work).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.V4 Type Sintered Porous Filter with Female Thread.
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