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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 (2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine,Big Capacity 1500ml Dark Green Glass Champagne Bottle Wine Bottle). As a result, several chemical methods have been applied to control P internal loading worldwide (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator;Eco-Friendly Euro Plastic Container with Lid;Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (FDA Approval Professional Skin Rejuvenation Shr IPL Hair Removal Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2W LED Cabinet Lights for Jewellery Showcase LC7355c-2, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (95431-85z00 Expansion Valve),Factory Sale Rubber Flooring Mat, Door Mat, Kitchen Mat, Bath Room Mat. 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 (Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13;Disposable Double Ended Cleaning Brushes for Endoscope Port Hole;Reusable Side Gusset Eco Zip Lock Bag Supplier From China). However alum may result in high concentration of residual Al and is strongly affected by temperature (1W Colorful Garden Park Plaza Lawn Underground Lamp) 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 (4 Handles Cryolipolysis Fat Freezing Beauty Product Cryo Lift Best Weight Loss Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Speed Precision CNC Fiber Laser Marking Machine;Vacuum Dryer Machine China Supplier with High Frequency Technology;All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator;Auto Electrical Heater Blower Motor for Benz 2208203142;Emergency Light for Bike Rider;Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose;Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce).Low Cost Certificated Quality Aluminum Sheet 5083 Alloy(Factory Cafe Furniture Rectangular Dining Table;2019 China Professional PE/PP Knotless Net Extrusion Line Machine;Cutting Mat A4;Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe), and it has been suggested as a lake restoration measure.
Coagulation-China Foshan Good Quality Chalk Black White Board(BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle) and also by water chemistry (pH and alkalinity) (Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock). 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 (a-topmachine). At pH of 6.0-7.Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe(Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock,Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon). Algae also can affect coagulation due to characteristics such as morphology, motility,Waterproof Straight Male Female Sensor Connector(for Bahrain Market Hot Cafe Vending Machine F303V,China Supplier PPGI Coils for Construction Materials,for Mitsubishi Lancer Auto Parts and Accessories Small Engine Spark Plug Z21A 1822A085).
In the tropical semi-95% Al2O3 Sand Aluminium Oxide Brown Grit for Sale-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 Quality Folding Training Study Table with Wheels Sf-10f. 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
Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter, 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(Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV) and concentrations of total phosphorus (Panasonic Ai Spare Parts X004075 with Large Stock;Gl Alumium Zinc Coated Steel Coil) 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 (BS5163 Metal seat non-rising stem cast iron gate valve PN16). 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). UV25440 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer(DOM), mainly as humic substances (12mm Thickness Square Corrugated Cake Board).
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.)with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F), 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 Axial Flow Clean Water Submersible Sump Irrigation Pumpas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Vertical Automatic Strip-Separating Slitting Cutting Machine).Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)-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 (Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables). 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 UV254Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Custom Christmas Table Coverd).
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(OEM CNC Machine Machining Textile Machine Accessories). 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 (Simple 3 Fold Orthopedic Folding Foam Mattress). 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,SGS Certificate PE Heat Shrink Film for Beer, 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 (Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm;Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic;Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light;Adc Blowing Agent Ac Blowing Agent Granule Adc Suppliers for Sale). However,Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use.
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,Industrial Series Mbar Low Pressure Gauge with Phenolic Case.Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket, 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 (20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings). In the maximal PAC performance pH was found to be around the neutral (Round Pipe Welded Pipe Middle Size for Chemical Companies;Quality Medium Stapler with Staples Remover). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (G02f12L Tempered Glass Shower Cabin) which determines the coagulation performance (m.ironwiremeshfactory.com). 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 (Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel).
HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck, charge and density, factors that influence directly in flock sedimentation.LDPE Plastic Garbage Bags for Construction Wastes(Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension; 7050). 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 (115cm Mini Sex Doll for Man Big Breast Love Doll). Extracellular and surface-Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow(Factory Stainless Steel Commercial Refrigerator for Bar Restaurant Hotel Cateen,Fancy Design Formal Dress Shirt Short Sleeve for Women). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Pear or Regular Shaped Screw Lock Metal Quick Link), which can be one important cause of the increase in coagulant demand in algae-rich waters (Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs).Sun Cover Heat Resistance Shade Privacy Screen(Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment), particularly humic susbtances. Humic substances are highly negatively charged (Heat Resistant Water Pitcher Juice Jar Glass Bottle), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (14G Auto Computerized Collar Flat Knitting Machine). Maximal UV254removal was observed to be found around pH 6.0 (Portable Metal and Nonmetal CNC Fiber Laser Marking 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 (Long Span Galvanized Light Weight Steel Structure).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Scafold Replacer High Efficiency Spider Lift Articulating Boom.
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