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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 (All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable,China Ahu Hepa Filter). As a result, several chemical methods have been applied to control P internal loading worldwide (Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier;Supply Carton Sealing Use and Rubber Adhesive Duct Tape;Customized Steel Wire Small Conveyor Belt System). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (1100),Diesel Fuel Leak off Pipe for Mercedes-Benz. 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 (Metallzied Polyester Film 9um MPET Film for Capacitor Use;Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display;Wholesale Gym Equipment Adjustable Boxing Target). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Quality Wholesale Men′s Leather Sneakers Boots) 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 (3 Pin Multi Plug Socket). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (12ml Small Dropper PE Plastic Medicine Bottle;PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine;Middle Duty 20 Discs Harrow for 50 HP Tractor;Hot and Cold Temperature Thermal Shock Testing Equipment;Multihead Weigher Packaging Machine for Snacks (JA-320/420/520/720/820);Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215;Newest Hot Sales Metal 360 Degree Reading Glasses with Case).Portable Medical Ozone Therapy Unit Zamt-80 on Sale(Hydraulic Press Machine Deep Drawing Press 100 Ton;Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder;PDC Diamond Enhanced Mining Pick Tool for Hard Rock Tunneling Excavation;FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wholesale Men′s Leather Waterproof Outdoor Trekking Boots), and it has been suggested as a lake restoration measure.
Coagulation-43L Big Volume Insulated Backpack Delivery Food/Pizza Bag(Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter) and also by water chemistry (pH and alkalinity) (Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)). 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 (Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet). At pH of 6.0-7.1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die(PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable,High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid(Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8,Forging SAE4140 S31803 Steel Crusher Eccentric Shaft,200 Micron Mesh Replacement Filter Stainless Steel Material for Water Filter).
In the tropical semi-Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair-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.Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls. 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
Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector, 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(Auto Price Crankshaft Position Sensor 90919-05043) and concentrations of total phosphorus (Duplex Hydraulic Oil Filter for Lubrication System;Roller Drying Pac) 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 (4 Fibers Wall-Mounted FTTH Distribution Box). 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). UV25440K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine(DOM), mainly as humic substances (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO).
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.)Hot Sale High Density Hotel Cashmere Wool Polyester Blanket, 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 to1/2 Inch Brass Stem Handwheel Gate Globe Valveas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(200A Lead-Acid Battery 12V Rechargeable Solar Gel Battery (QW-GEL200)).Home Furniture Metal Chair Grey Velvet Dining Chair-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 (Waste Pet Plastic Bottle Crushing Washing Recycling Machine). 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 UV254168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Glass Mike Bottle 200ml 250ml with Screw Cap Straws). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (N & L Chinese Furniture Modern Design Kitchen Cabinetd).
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(2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part). 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 (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug). 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,OEM High Efficiency Polycrystalline 260W Solar Panel, 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 (Modern Style Prefabricated Steel Structure Poultry House; Splicing Machine S6;Double Deck High Quality Aluminum Pontoon Boat for Sale;Hot Sale Floor Standing Cabinet Network Cabinet). However,Basketball Rebounded Practice Machine for Professional Trainer (S6839).
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,DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil.Customized Sand Casting Brake Wheel Hub for Trailer and Truck, 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 (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)). In the maximal PAC performance pH was found to be around the neutral (Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes;Floor Mounted Glass U Clamp Channel for Glass Balustrade). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Curve Spear Tunnel Bolt for Concrete Ring) which determines the coagulation performance (Cnc Router 5 Axis). 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 (Brand New Forklift with Double Front pneumatic Tire).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant.
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