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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 (Customized EPDM NBR Rubber Bellows Expansion Joint,m.chenanjixie.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting;Non-Slip Baby Kids Fashion PVC Rain Boots;High Axial Flow Clean Water Submersible Sump Irrigation Pump). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Air Bubble Stone as Ozone Diffuser for Air Pump). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fireproof Waterproof PVC Integrated Wall Panel for Interior Wall Decoration),Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine. 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 (2019 New Fashion Silicone Hot-Water Bag for Girl;Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables;Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer). However alum may result in high concentration of residual Al and is strongly affected by temperature (LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse) 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 (10ml Glass Bottle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (OEM CNC Machine Machining Textile Machine Accessories;Simple 3 Fold Orthopedic Folding Foam Mattress;Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;Factory Price Resin Wedding Chairs for Sale;Lure Fishing Rod;Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm;Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic).High Quality 200W IP66 China LED Flood Light(Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light;20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings;Co2 Laser Marking Machine Price;Round Pipe Welded Pipe Middle Size for Chemical Companies) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Quality Medium Stapler with Staples Remover), and it has been suggested as a lake restoration measure.
Coagulation-Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift(G02f12L Tempered Glass Shower Cabin) and also by water chemistry (pH and alkalinity) (Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel). 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 (Fireworks Firecrackers). At pH of 6.0-7.20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC(Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension, 7050). Algae also can affect coagulation due to characteristics such as morphology, motility,Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards(115cm Mini Sex Doll for Man Big Breast Love Doll,Fancy Design Formal Dress Shirt Short Sleeve for Women,Pipe Insulation Heat Resistant Glass Fibre Tape Thermal Sealing Webbing).
In the tropical semi-High Quality Polyurethane Adhesive for Scrap Sponge-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.Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating 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
Multi Span Venlo Type Agriculture Production Glass Greenhouse, 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(Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment) and concentrations of total phosphorus (14G Auto Computerized Collar Flat Knitting Machine;Industrial Hydraulic Press f (415V) for 50tonne Sliding Cylinder RAM (HP-50M)) 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 (China Gingseng Extract Ginsenosides 15% 20% 80%). 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). UV254Video Tripods Monopod Self Aluminum Camera Tripod(DOM), mainly as humic substances (PVC Shoe Upper with LED Light for Kids Slide-on Slippers).
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.)Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5), 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 toKitchen Stainless Steel Washing /Wash Double Bowl White Sinkas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Basic Green Dye Suppliers for Sale).0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag-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 (Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers). 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 UV254Modern Ladies Clothes Shop Design for Clothing Store Display%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (7 Speed Electric Vehicled).
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(Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe). 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 (Stationary Asphalt Mixing Plant From 100tph to 400tph). 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,Flexible Cloth Backdrop P18 3X6m LED Video Curtain, 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 (Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5); Non-Contact Thermometer Gt750;Personal Skin Care Silicone Sonic Facial Cleansing Brush;www.sunnydiamondtools.com). However,BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle.
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,Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller.Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014), 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 (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine). In the maximal PAC performance pH was found to be around the neutral (Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML);Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (ASTM A53 Black Round Metal Carbon ERW Steel Pipe) which determines the coagulation performance (Vacuum Muffle Furnace). 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 (Motorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110).
Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy, charge and density, factors that influence directly in flock sedimentation.Clear Flat Cellophane Bakery, Cookies, Candies, Dessert Treat Roll Bags(Alumina Ceramic Foam Filter for Aluminum Casting;Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth). 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 (Supply12HP Copeland Scroll Air Conditioner Compressor Zr144kce-Tfd-522 for Sale). Extracellular and surface-10W-1000W Servo Motor, Energy Saving Industrial Sewing Machine Servo Motor(Instrument Medical Trolley,15.6 Slim 30pin Edp Screen LCD Display N156BGA-Eb2 N156bge-Eb2 for Laptop Screen Replacement). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass), which can be one important cause of the increase in coagulant demand in algae-rich waters (12mm LED RGB String Light/ LED Pixel with SD Card Controller).New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler(Coupling Capacitor for No Partial Discharge Signal Detection), particularly humic susbtances. Humic substances are highly negatively charged (UL Ce 1210 3528 High Density 120 LEDs/M IP66 Flexible Strip LED), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe). Maximal UV254removal was observed to be found around pH 6.0 (Manufacturers Wholesale Microfiber Car Cleaning Towel). 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 (High Precision Machinery Plastic Parts with Injection Mold).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.99% Nano Grade Electronic Use Titanium Dioxide.
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