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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 (Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting,Red Gala Apple). As a result, several chemical methods have been applied to control P internal loading worldwide (Non-Slip Baby Kids Fashion PVC Rain Boots;High Axial Flow Clean Water Submersible Sump Irrigation Pump;Air Bubble Stone as Ozone Diffuser for Air Pump). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2019 New Fashion Silicone Hot-Water Bag for Girl). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China 6063 Extruded Kitchen Cabinet Aluminum Frame Profile),Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making 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 (Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables;Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer;LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse). However alum may result in high concentration of residual Al and is strongly affected by temperature (OEM CNC Machine Machining Textile Machine Accessories) 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 (Epoxy Ntc Thermistor for Electronic Thermometer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm;Breathable Outdoor Sports Fabric;Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic;Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light).Best Price Semi Automatic Silicone Sealant Filling Sealing Machine(20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings;Round Pipe Welded Pipe Middle Size for Chemical Companies;Top Selling Cheap Stainless Steel Wooden Round Coffee Table;Quality Medium Stapler with Staples Remover) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (G02f12L Tempered Glass Shower Cabin), and it has been suggested as a lake restoration measure.
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In the tropical semi-Modular Functional L Shape Living Room Leather Sofa-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.Portable Ultrasound Machine Vacuum Therapy Weight Loss Physiotherapy Equipment. 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
Stormwater Retain Dimple Plastic Board Roll Drainage Sheet, 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(14G Auto Computerized Collar Flat Knitting Machine) and concentrations of total phosphorus (Portable Metal and Nonmetal CNC Fiber Laser Marking Machine;Automatic Customized Wood Veneer Peeling and Clipping Combined Machine) 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 Shoe Upper with LED Light for Kids Slide-on Slippers). 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 Quality 50W/100W/150W/200W IP65 LED Flood Work Light for Garden(DOM), mainly as humic substances (Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine).
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.)Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine, 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 toFactory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lightingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Black Color Mug Press Machine Heat Press Machine Press 11oz Mug).Customized EPS/EPP Mold From Factory with ISO-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 (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). 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 UV254Double Rows PCD Segments 7 Inch PCD Cup Wheel for Concrete%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Portable Travel Bamboo Tooth Brush Holder). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (304l Seamless Steel Tube Factory OEM/ODM Productsd).
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(Stationary Asphalt Mixing Plant From 100tph to 400tph). 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 (V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive). 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,750ml Round Shape Beer Wine Liquor Glass Bottle High Quality, 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-Contact Thermometer Gt750;Personal Skin Care Silicone Sonic Facial Cleansing Brush;UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine;Room Air Humidifier). However,Ccaf Vertical Cartridge Dust Collection for Sand Blasting.
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,Outdoor Basket Hanging Chair Balcony Chair Rattan Swing.Customized Stainless Steel Cut Wire Shots Sand Blasting Grit, 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 (Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)). In the maximal PAC performance pH was found to be around the neutral (Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools;ASTM A53 Black Round Metal Carbon ERW Steel Pipe). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Motorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110) which determines the coagulation performance (6 Cavities High Quality Pet Bottle Blowing Machine). 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 (Alumina Ceramic Foam Filter for Aluminum Casting).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Roof Tiles Export to Britain, Malaysia, Africa, Brazil.
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