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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 (OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat,Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light). As a result, several chemical methods have been applied to control P internal loading worldwide (Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085);20qt Portable Small Rotomolded Insulated Medical Cooler Box;Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Multi Span Venlo Type Agriculture Production Glass Greenhouse, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hansel Outdoor Electric Rides Adult Amusement Motorcycles),Video Tripods Monopod Self Aluminum Camera Tripod. 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 (Quick Charger 18W USB-C Pd Charger for iPhone11;75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display;Carboxy Methyl Cellulose (CMC) for Daily Use). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fng Fgg 0b 2 3 4 5 6 7 9pins High Quality Circular Cable Connector with Release Yard) 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 (Factory Supplying Ductile Iron Rectangle Gully Sewer Drain Manhole Cover for OEM Services). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Outdoor LED Courtyard Solar Street Lights for Garden Path Road;Equipment Auto Fire Extinguisher Ball Automatic Fire Extinguisher Ball;Black Matt Strong Metal Bag Slider Zip Pullers;3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves;Small Stainless Steel Padlock;1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire;China Supplier Good Quality Bending U Bolts Parts).Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)(OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag;Automatic Control Apricot Shell Charcoal Carbonization Kiln Price;Push Up Teddy Bodysuit;304L 316L Stainless Steel Sheets From Ticso) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices), and it has been suggested as a lake restoration measure.
Coagulation-0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag(Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove) and also by water chemistry (pH and alkalinity) (750ml Round Shape Beer Wine Liquor Glass Bottle High Quality). 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 (Car Air Filter Air Cabin Filter for Toyota Land Cruiser Hilux Coaster 17801-58010). At pH of 6.0-7.Modern Ladies Clothes Shop Design for Clothing Store Display(M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher,6 Head Garment Computerized Embroidery Machine Industrial Use for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Flexible Cloth Backdrop P18 3X6m LED Video Curtain(Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale,4-Way Brass Angle Valves Chrome Plated Water Supply Stop,Wood Chipper Machine).
In the tropical semi-BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle-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.Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller. 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
Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014), 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(Wallbox Socket Type 2 16A 3.7kw Single Phase EV Charging Point EV Charger for Electricvehicles) and concentrations of total phosphorus (Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton;Automatic 0.5kg Powder Fire Extinguisher Auto Ball Fire Extinguisher Ball Price) 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 (Customized Speed 110V-220V 60X60X25mm Axial Brushless Cooling AC Ec Powerful Fan). 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). UV254Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy(DOM), mainly as humic substances (2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer 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.)Clear Flat Cellophane Bakery, Cookies, Candies, Dessert Treat Roll Bags, 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 toCustomized Plastic Injection Mould Products Industrial Parts Plastic Cross Pipeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(DJ Equipment Bar and Night Club Decoration LED Kinetic System).10W-1000W Servo Motor, Energy Saving Industrial Sewing Machine Servo Motor-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 (9-80V Laser Red Zone LED Work Safety Lights for Forklift Truck). 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 UV254New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Triangle Plastic Checkout Counter Divider Bar with Logo Printed). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (White Powder Calcium Chloride for Refrigerating Fluidd).
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(Digital Control Gold Powder Coating Machine for Metals). 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 (Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion). 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,99% Nano Grade Electronic Use Titanium Dioxide, 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 (Real-Time GPS Padlock Container Tracker GPS Tracking Car/Truck Fleet Management;Outdoor Food Truck Mobile Food Car for Sale;Durable Soft Polishing Wheel for Polishing Wood and Plastic;Comenda Dishwasher Parts). However,630kgs Galvanized Suspended Platform, Electrical Suspend Working Platform, Swing Stage.
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,A76 Nordic Living Room Dining Room Furniture.Good Quality Brow Pencil Pencil Private Label Wholesale, 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 (Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe). In the maximal PAC performance pH was found to be around the neutral (Medical Equipment One Step Tp Device Syphilis Rapid Test Kit;Agricultural Machinery Partslinear Bearings Kh3050). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( 12V- 48V DC) which determines the coagulation performance (80-160g Bath Ball Fizzer and Bath Bomb for SPA Bathing). 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 (Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037.
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