Compact Treatment Research Articles

АНАЛИЗ ТЕХНИЧЕСКИХ РЕШЕНИЙ КОМПАКТНЫХ УСТАНОВОК ДЛЯ ОЧИСТКИ СТОЧНОЙ ЖИДКОСТИ

Introduction. In this paper, we consider the operation principle, features, advantages, and disadvantages of compact domestic wastewater treatment plants designed by domestic manufacturers. The compact plants used until 2000 were designed to reduce such two indicators in the waste liquid as BOD and suspended solids. Since 2000, modern compact plants capable of reducing four indicators (BOD, suspended solids, nitrogen, and phosphorus) have been developed and installed in Russia. Methods. Biological methods of removing organic substances and nitrogen from the waste liquid are used at modern compact plants. Phosphorus is removed by using both biological and physical-and-chemical methods. The main issue in the operation of compact domestic wastewater treatment plants is the extremely nonuniform flow of wastewater; the coefficient of hourly nonuniformity can be 3.5 or higher. Another serious issue is the reduction in the waste liquid temperature in the cold period to critical values that hinder the biochemical oxidation of organic substances in aeration tanks. In permafrost areas (Yakutia), the influence of this factor can be observed even in the warm period. Results. Based on theoretical research and many years of experience in commissioning, we identified the consequences of design flaws and violations during operation for the stability and performance efficiency of compact plants of various modifications. Conclusion. The performed study made it possible to develop and recommend the optimal option for wastewater treatment, which allowed us to ensure that the indicators were brought to the maximum permissible concentrations of pollutants (suspended solids — 2–3 mg/l, BODult — 3–5 mg/l, ammonium nitrogen — 0.4 mg/l, nitrate nitrogen — 9 mg/l, phosphorus — 0.2 mg/l), established for discharge into fishing reservoirs.

Correlation between microstructures and tensile deformation behavior of a PM near α Ti–6Al–2Sn–4Zr–2Mo−0.1Si alloy

A powder metallurgy (PM) near α Ti–6Al–2Sn–4Zr–2Mo−0.1Si (wt.%) alloy was fabricated by in-situ dehydrogenation and hot extrusion of a TiH2-based powder compact and heat treatments. Three types of microstructures were obtained in the as-consolidated state and after different heat treatments. They are a basketweave microstructure consisting of a network of inter-penetrating α plates filled with domains of ultrafine β transformed structure (βt) (Type I microstructure), an α/β lamellar microstructure with most β layers being thin and discontinuous plus α layers at prior β grain boundaries (Type II microstructure) and an α/βt lamellar microstructure (Type III microstructure). Although the three types of microstructures render the alloy with a similar yield strength (1085–1109 MPa) and ultimate tensile strength (1217–1239 MPa) due to the balanced effects of various strengthening mechanisms, the Type II microstructure exhibits a significantly lower tensile ductility than the other two types of microstructures (elongation to fracture: 5.5% vs. 13–14%). Examination of dislocations in the tensile deformed specimens reveals that dislocations cutting through the thin β layers in the Type II microstructure during deformation. Such interactions between moving dislocations and thin β layers in the Type II microstructure are expected to be the primary reason for the clearly lower strain hardening rate, premature fracture of grain boundary α layers and low tolerance to strain localization observed in the tensile tests, fracture surface examination and DIC analysis. This correlation between the microstructures and tensile deformation behavior strongly suggests that preventing moving dislocations cutting through thin β layers by turning them into thicker and ultrafine structure strengthened βt lamellae or blocks is critically important in ensuring high tensile ductility of high strength PM near α titanium alloys.

Treatment of the complex liquid phase that contains produced water, condensate oil, and floccule from an offshore gas field: A pilot system for the South China Sea

Produced water (PW) of the liquid phase is the largest volume by-product from the process of offshore oil and gas production, and compact and efficient treatment methods are brought into focus. The PW, condensate oil, and floccule in the liquid phase all require treatment to satisfy the requirements of the standards. The liquid phase volume from offshore gas fields is typically not as large as that from offshore oil fields. The presence of the floccule and severity of emulsification, however, cause higher levels of treatment difficulty. Ecological damage to the ocean and some other potential hazards can be caused if PW discharged into the ocean contains oil that exceeds the concentrations of the value, of which ranges from 15 mg/L to 50 mg/L according to different standards. Condensate oil phase pipes may also be corroded if the oil phase is not well treated. This study examines a pilot system with the capacity of 0.5 m3/h, that includes pre-, PW, and condensate oil treatments performed at an industrial offshore gas field platform on the South China Sea. The water and oil phases were transparent in appearance. The concentration of oil in the PW discharged to the ocean was less than 50% of the value of the relative standards. The concentration of water in the condensate oil was lower than 200 mg/L, which satisfied the requirement of this platform for transportation by submarine pipelines. The accumulative floccule in the liquid phase was also gathered using a filter bag that proceeded a virtuous circle due to the avoidance of the accumulation of the floccule. This pilot system provides a novel solution method for the liquid phase from offshore gas fields containing highly emulsified PW, condensate oil, and floccule, which diffuses between the PW and the condensate oil.

Using the Forestry Reclamation Approach for Reclaimed Surface Mineland in the Western Gulf: Effects on Pinus taeda Seedling Growth and Survival

While land reclamation efforts of surface mines have considerably increased soil stability since the implementation of SMCRA (Surface Mining Control and Reclamation Act), research suggests that resulting soil compaction hinders the productivity of forests post-mining. The Forestry Reclamation Approach (FRA) was developed to improve forest health in the Appalachian region through a five-step process that minimizes soil compaction and establishes a productive forest. The FRA has not yet been tested in the western Gulf Coastal Plain (GCP). The higher clay content of some GCP soils and the dearth of coarse fragments (e.g., cobbles, stones and boulders) may affect reclamation practices and the ability of these methods to create productive forests. Compaction caused by conventional reclamation methods in the GCP has not been studied in great detail. Thus, this study attempts to provide a comparison of two reclamation methods, FRA low-compaction method used in the Appalachian region with that of conventional scraper-pan (scraper) methods in the GCP. This study used the FRA with common silvicultural practices of the western Gulf. The two hectare study site was installed with a randomized complete block design with three replicates comparing conventional scraper reclamation used in the region with that of an unmined control and the FRA-style low compaction treatment. Following soil reclamation, containerized loblolly pine (Pinus taeda L.) seedlings of a western Gulf provenance were hand-planted. Soil chemical and physical parameters were assessed on each treatment to determine the effect the FRA and scraper method had on resulting tree seedling growth and survival. After three growing seasons, seedlings in the FRA plots had significantly greater tree volumes than both the scraper (p = 0.0139) and the control (p = 0.0247) treatments. The FRA plots also had a 97% survival rate, while scraper plots had a survival of 86%. The FRA plots had significantly lower soil bulk densities than scraper (p = 0.0353) and control (p < 0.0001) plots which likely influenced growth and survival trends. Soil nutrients were increasingly available on the FRA and scraper plots, likely due to mixing of the soil profile when compared to the unmined control. Leaf-level water potential and gas exchange were not correlated to growth and survival and did not differ among treatments. These results suggest reclamation practices modeled after FRA methods may benefit tree growth and survival in the Western Gulf.

Long-term effects of organic matter removal, compaction, and vegetation control on tree survival and growth in coarse-textured, low-productivity soils

The Long-Term Soil Productivity Network is providing a systematic examination of the effects of organic matter removal and compaction on a variety of different soils and forest types across North America. Here we report on the 22nd-year survival and height growth of white oak (Quercus alba), northern red oak (Q. rubra), and shortleaf pine (Pinus echinata) on rocky, nutrient-poor soils that have a low to moderate water holding capacity in the Missouri Ozark Highlands. Treatments included three levels of organic matter removal (sawlog, whole tree, and whole-tree plus forest floor) and three levels of soil compaction (none: bulk density = 1.34 g cm−3; moderate: bulk density = 1.65 g cm−3; and severe: bulk density = 1.78 g cm−3) each with and without vegetation control. Following treatments, bareroot, 1–0 white oak, northern red oak, and shortleaf pine seedlings were planted at a 3:3:1 ratio, approximating the distribution of these species in this region. Within half of each plot, a vegetation control treatment was applied for the first 10 years by treating competing vegetation with herbicide. After 22 years, vegetation control significantly increased biomass and height of all planted species. The average height for northern red oak with vegetation control treatments was 884 cm with vs. 606 cm without; white oak was 837 cm with vs. 424 cm without; shortleaf pine was 1339 cm with vs. 1220 cm without. Moderate compaction increased average white oak height by 15% and severe compaction increased average height by 18% compared to no-compaction treatments. Compaction was not a significant treatment for red oaks or for shortleaf pines. However, the coarse fragments in the study soils appear to have muted much of the compaction to the soil’s fine-earth fraction and may have had the unintended effect of providing partial vegetation control. Whole-tree removal reduced average shortleaf pine heights by 6% vs. sawlog-only removal, while whole-tree + forest floor removal increased heights 3% compared to sawlog harvests. Organic matter removal was not a significant treatment for either oak species. Red oak survival probability was 0.79 with vegetation control vs. 0.34 without; white oak was 0.81 with vs. 0.65 without; shortleaf pine was 0.49 with vs. 0.45 without. Overall, vegetation control was the dominant factor driving survival and growth of oaks, and to a lesser degree, growth of shortleaf pine. Organic matter removal and compaction treatments had relatively little negative effect on height, indicating the resilience of these species to harvest-related disturbances in Ozark Highlands soils.

Five-year growth, biomass, and nitrogen pools of Douglas-fir following intensive forest management treatments

In young Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands, intensive forest management has resulted in variable responses in survival and growth and therefore stand biomass due to effects on microclimate and competition for limited resources. As seedling genetics and management practices develop over time, there is a need to re-evaluate how Douglas-fir survival and growth varies with intensive practices. Five-year Douglas-fir diameter at 15 cm (D15) and height growth, biomass, and nitrogen (N) pools after organic matter removals and soil compaction at a recently established site in central Oregon (NARA) were compared to five-year results from three Douglas-fir sites with organic matter removal and vegetation control treatments that were established 10–14 years earlier in central Washington (Fall River and Matlock) and northern Oregon (Molalla). The NARA site contained up to two times greater individual-tree foliar and branch biomass for the same stem D15 than the previously established sites, possibly due to a lower planting density, a warmer climate, and/or improved genetics/different seed sources. Prediction of stem biomass was similar at all sites using D152*height. Periodic D15 and height growth from 1 to 3 years and five-year Douglas-fir biomass was lower in the bole-only (BO) without compaction treatment at NARA compared to other treatment combinations. Greater periodic D15 and height growth after five years of annual vegetation control (Fall River, Matlock, and Molalla) resulted in larger Douglas-fir biomass compared to the initial vegetation control treatments. These results indicate the beneficial effects of vegetation control on early growth across a wide range of conditions. With one exception, whole-tree removal treatments did not affect five-year-old Douglas-fir biomass or N pools, indicating site resilience to increased OM removal across the region. A principal component analysis (PCA) clearly separated all four sites according to climate, soil temperature and moisture, N availability, D15 and height growth, and Douglas-fir and competing vegetation biomass. Within each site, the PCA showed that vegetation control was associated with the greatest differences in Douglas-fir and competing vegetation biomass. This supports the notion that site factors and vegetation control treatments are critically important in mitigating response to intensive management practices.

Decomposition of wood stakes in the Pacific Northwest after soil compaction and organic matter removal

Forest operations can affect soil productivity by impacting the amount and distribution of surface organic matter (OM) and changing the properties of surface mineral soil. The North American Long-Term Soil Productivity Study (LTSP) was developed to address such long-term changes after pulse disturbances associated with clearcut harvesting, soil compaction, and OM removal across a wide spectrum of forest sites. From 2000 to 2002 we established a study to assess the impact of four soil disturbance treatments on OM decomposition in the mineral soil on seven LTSP study plots from southern British Columbia, Canada to southern Oregon, USA. The soil treatments were combinations of two levels of compaction and organic matter removal: 1) removal of only merchantable logs [OM0] , 2) removal of all the forest floor and woody material [OM2], 3) no soil compaction after harvest [C0], and 4) “severe” soil compaction after harvest [C2]. Aspen (Populus tremuloides Michx.) and pine (Pinus taeda L.) wood stakes were inserted into the mineral soil of each treatment plot and in an adjacent unharvested control stand to a depth of either 20 or 30 cm (depending on soil depth). At the end of three years the soil compaction and the OM removal treatments had relatively little effect on pine or aspen stake decomposition at the British Columbia study sites. In the United States, soil compaction increased decomposition on the two study sites with coarse-texture mineral soil with surface OM intact. Three key findings were: (1) a strong positive relationship (p = 0.0009) between stake water content and stake mass loss, (2) aspen and pine stake decomposition was greater in the clearcut-LTSP treatments than in the unharvested stands, (3) the rehabilitation of the compacted soil treatment on the British Columbia study sites generally increased wood stake decomposition. However, overall, there were no consistent wood stake decay trends across all sites and LTSP treatments.

Thermistors manufactured from nioubium oxide in the ZrO2-Bi2o3 / Termistores manufacturados de óxido de nioúbio no ZrO2-Bi2o3

Thermistors are thermal resistors that allow high changes in the dielectric constant due to the sensible temperature change. The thermistors can be P.T.C.R and N.T.C.R. They are devices applied within the oil exploration industry, automobiles and electronics. The ceramic powders were obtained from stoichiometric quantities by ball milling with subsequent compaction, sintering and heat treatment from 825 ° C for 24 hours and cooled to room temperature. The samples were characterized by X-ray diffraction, scanning electron microscopy, calculation of the apparent density, dielectric constant and qualitative thermistor factors, called temperature coefficient and characteristic ratio. The samples from the mixture between the niobium zirconia-bismuth oxides obtained significant results for commercial and industrial application in the respective temperature ranges, between 30ºC-80ºC and 460ºC-600ºC.

Slow Sand Filtration for Cercariae Removal in Rural Egypt.(Dept.C)

In 1990, El-Mansoura University signed a contract with the international Development research Center IDRC to conduct an integrated research to field test the process of slow filtration. A pilot plant was constructed and installed in Sandoop Compact Water Treatment Plant in El-Mansoura City. The pilot plant consists of an intake, Up flow Roughing Filter (URF), and four SSP's. The raw water source was El-Bahr El-Saghier Canal, a branch of the Nile River. A slug of 10000 cercariae units in one liter was dropped on the water surface at each of three filters, no presence of cercariae at the final effluent of the SSF were detected. At some depths across the sand layer positive samples were identified. During this study twenty samples from the effluent of the tested slow sand filters; the URF, and the compact treatment plant were collected. Out of the 20 samples positive results showed nil after the SSF, 5 after the URF and, 3 after the compact unit. These results indicated the efficiency of the SSF in removing cercariae.

Building Pareto Frontiers under tree-level forest planning using airborne laser scanning, growth models and spatial optimization

This article evaluates the conflicts between spatial, production and financial goals using tree-level decision-support built from stand dynamics equations, airborne laser scanning data and optimization based on mixed integer programming. The resulting Pareto Frontiers evaluated the role of spatial goals to create compact treatment areas along the 10-year forest plan composed of two periods. The weight of spatial goals was progressively increased to quantify the trade-offs towards (1) financial performance, (2) timber production, (3) clustering of harvesting decisions and (4) the Hart-Becking stand density index computed at tree-level using regions derived from ALS. The proposed framework was illustrated in pine forest located in Central Spain using tree-level inventory. The proposed tree selection method was feasible and provided results fast to support operational decision-making. Proved feasibility of the tree selection method optimization allowed the fast PF computation. The results showed the benefit of increasing the weight of spatial goals up to 20–40% to promote the clustering of tree harvests. The observed reduction of financial revenues from increasing priority to spatial clustering paid off, financially and operationally, considering the possible implementation of solutions, which were very dispersed when fully maximizing revenues or benefit. The assimilation of the Pareto Frontier supported with robust optimization contributes to improve forest management planning efficiency. This article turns tree-level decision making into contemporary by integrating multi-temporal decisions, using multi-objective scenarios to assess preferences, and making use of ALS technology as the vector to transform forest data into management decisions.

REGRESSÃO QUADRÁTICA PARA TEORES DE ÁGUA EM FUNÇÃO DA COMPACTAÇÃO DO SOLO

REGRESSÃO QUADRÁTICA PARA TEORES DE ÁGUA EM FUNÇÃO DA COMPACTAÇÃO DO SOLO Barbara Barreto Fernandes¹; Indiamara Marasca²; Murilo³ Battistuzzi Martins; Jefferson Sandi4 e Kleber Pereira Lanças5 1 Engenheira agrônoma, Rua Luis Carlos Da Silveira, 345, Tenis Clube, 19806-370, Assis – SP, Brasil. E-mail: babarretof@hotmail.com 2 Engenheira agrônoma, Fazenda Cachoeira do Montividiu – 75915-000, Montividiu – GO, Brasil. E-mail: marasca_7@hotmail.com 3 Universidade Estadual de Mato Grosso do Sul – Unidade de Cassilândia. Rodovia MS 306 - km 6,4; 79540-000, Cassilândia, MS, Brasil. E-mail: mbm_martins@hotmail.com 4 Universidade La Salle de Lucas do Rio Verde. Av. Universitária, 1000, Parque das Emas - 78455-000, Lucas do Rio Verde, MT, Brasil. E-mail: jffsandi@gmail.com 5 Departamento de Engenharia Rural na FCA/UNESP, Av. Universitária, 3780 - Altos do Paraíso, 18610-034, Botucatu, SP, Brasil. E-mail: kp.lancas@.unesp.br 1 RESUMO O trabalho teve por objetivo avaliar a influência do teor de água na avaliação de resistência mecânica a penetração do solo, medida através do índice de cone. O experimento foi realizado na UNESP/FCA, Botucatu-SP, sendo selecionadas duas classes de solo: o Nitossolo Vermelho distroférrico e o Latossolo Vermelho. Utilizou-se o delineamento inteiramente casualizado, com os seguintes tratamentos de compactação: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4=5 e T5 = 10 passadas consecutivas de um trator agrícola. Utilizou-se um penetrômetro hidráulico-eletrônico para a amostragem da resistência mecânica do solo à penetração nas camadas de: 0,00 - 0,10; 0,10 - 0,20; 0,20 - 0,30; 0,30 - 0,40 m em quatro condições de teor de água. Com o aumento do tráfego, maior foi a compactação. Porém para o solo argiloso, a partir de uma passada do trator, os valores de resistência à penetração tiveram pouco aumento, não diferindo estatisticamente para a camada mais superficial (0-0,20 m) e para a camada de 0,20-0,40 m a partir de duas passadas. Para o solo de textura média, este comportamento foi observado a partir de uma passada para a camada mais superficial (0-0,20 m) e de cinco passadas para a camada de 0,20-0,40m. Palavras-chave: resistência do solo, umidade, agregação. FERNANDES, B. B.; MARASCA, I.; MARTINS, M. B.; SANDI, J.; LANÇAS, K. P. QUADRACTIC REGRESSION FOR WATER CONTENTS IN THE FUNCTION OF SOIL COMPACTION 2 ABSTRACT The objective of this work was to evaluate the influence of water content in the evaluation of mechanical resistance to soil penetration, measured through the cone index. The experiment was conducted at UNESP/FCA, Botucatu - SP, being selected two classes of soil: a Nitossolo Vermelho distroférrico and a Latosolo Vermelho. A completely randomized design was used, with the following compaction treatments: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4 = 5 and T5 = 10 consecutive passes of an agricultural tractor. A hydraulic-electronic penetrometer was used to sample the mechanical resistance of the soil to penetrate the layers; 0.00 – 0.10; 0.10 - 0.20; 0.20 - 0.30; 0.30 - 0.40 m in four water content conditions. With the increase in traffic, greater was the compression. However, for the clayey soil, from a tractor pass, the penetration resistance values ​​had a small increase, not differing statistically for the most superficial layer (0 - 0.20m) and for the 0.20 - 0.40 m layer from two passes. For medium textured soil, this behavior was observed from one pass to the most superficial layer (0 - 0.20 m) and five passes to the 0.20 - 0.40 m layer. Keywords: soil resistance; moisture; aggregation.

Response of soil health indicators to organic matter removal and compaction manipulations at six LTSP sites in the Western US

Forest soils control many ecosystem services that enable and support primary forest productivity. Therefore, maintaining the health of the soil is critical to sustainable forest management. The long-term soil productivity (LTSP) experiment was initiated to increase our understanding of how the soil responds to pulse harvest disturbance and experiments have enabled tracking of soil health parameters across many diverse forest types. The purpose of this study was to investigate the effect of organic matter (OM) removal and compaction manipulations on soil health indicators at six long-term LTSP sites (study durations 16–25 years) in the Pacific Northwest and Northern California, USA.We hypothesized that only the most severe OM removal treatment would exhibit decreased soil nutrient pools and reduced biological processes and compaction would have less detrimental impact on soil properties than OM removal treatments. We collected mineral soil samples at six LTSP sites and measured soil health properties related to nutrient pools (total soil carbon (C) and nitrogen (N), active C) and biological processes (C and N mineralization and enzymatic potential activity). Our results indicate that the effects of OM removal treatments are more prominent than those effects of compaction treatments. Despite variation in inherent site properties, we did find consistent evidence that severe harvesting treatments may disrupt mineral soil functions and remain detrimental to most soil health measurements, even after 16–25 years. In contrast, bole-only and whole-tree removal treatments did not have this effect on soil parameters indicating these practices may not incur such long-lasting or deleterious effects. These results indicate the importance of reducing soil disruption due to harvesting in order to maintain ecosystem functions and highlights the importance of understanding the range of impact harvesting practices may have on forest soil health.

Compact wastewater treatment process based on abiotic nitrogen management achieved high-rate and facile pollutants removal

Chemically enhanced primary treatment (CEPT), ammonium ion exchange and regeneration (AIR) and membrane bioreactor (MBR) were coupled as CAIRM to treat domestic wastewater compactly and efficiently. CAIRM achieved efficient removal of chemical oxygen demand, ammonia nitrogen, total nitrogen (TN) and total phosphorus with total hydraulic retention time of 4.6 h, and obtained 2.3 ± 0.9 mg/L TN in the effluent. CEPT removed phosphate and impurities and prevented AIR from pollution. AIR maintained excellent nitrogen removal with a slight decrease in the exchange capacity of ion exchangers. MBR polished the effluent from AIR, and the larger particle size and better dewaterability of sludge mitigated the membrane fouling. Many heterotrophic genera, such as Rhodobacter and Defluviimonas, were enriched in the oligotrophic MBR. This study demonstrates the viability and stability of CAIRM in efficient wastewater treatment, which will address critical challenges in insufficient nitrogen removal and high land occupancy of current processes.

Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability k g as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing k g with an increase of DOC (i.e. k g,65% > k g,80% > k g,95% ) at a relatively low suction range (< 200 kPa) because both biochar and compaction treatment reduce the connected pores.

Trophic status, phytoplankton diversity, and water quality at Kafr El-Shinawy drinking-water treatment plant, Damietta

Abstract This work aims to study the seasonal fluctuation in physicochemical characteristics, trophic status, and some pollutants influencing phytoplankton diversity, and water quality at a compact Kafr El-Shinawy drinking-water treatment plant, Damietta – Egypt seasonally during 2018. Phytoplankton distribution was affected by the trophic status of water, level of pollutants, and physicochemical treatment processes of water. The predominance of phytoplankton species, especially Aphanizomenon flos aquae (Cyanophyta), Gomphosphaeria lacustris (Cyanophyta), Microcystis aeruginosa (Cyanophyta), Nostoc punctiforme (Cyanophyta), Oscillatoria limnetica (Cyanophyta), Pediastrum simplex (Chlorophyta), and Melosira granulata (Bacillariophyta) in treated water was much less than that in raw water. Trihalomethanes (THMs) levels in treated waters were higher than in raw water, while lower concentrations of heavy metals were recorded in treated water. Intracellular levels of microcystins were lower, whereas the extracellular levels were higher in treated water than raw water, and the former recorded the highest level in raw water during summer. Hence, the levels of dissolved microcystins and THMs in treated water were higher especially during summer, the season of luxurious growth of Microcystis species. Trophic state index (TSI) was relatively high in raw water compared with treated water due to high concentrations of nutrients (total-P, total-N, nitrite, nitrate, and ammonia) in raw water.

Synergistic effect of graphene/boron nitride binary nanoparticles on aluminum hybrid composite properties

In this study, hexagonal boron nitride nanoparticulates (BN: 0.5, 1, 1.5, 2 wt.%) and graphene nanoplatelets (GNPs: 0.15, 0.30, 0.45 wt.%) reinforced hybrid aluminum matrix composites were produced via the powder metallurgy (PM) process. In this process, mixing, dispersing, drying, filtering, compaction, and heat treatment were applied. The microstructure, Vickers hardness, density, compressive strength, and phase analysis of Al-BN, Al-BN-graphene composites, and pure Al were evaluated. The phase and microstructural analyses of the specimens were examined by an X-ray diffraction device and a scanning electron microscope. The results showed that maximum density (2.63 ± 0.01 g/cm3), minimum porosity (2.6%), maximum micro Vickers hardness (58 ± 1.5 HV), and the highest ultimate compressive strength (260 MPa) were achieved at Al-1BN-0.15GNP composite compared with pure Al and Al-BN. A significant improvement in ultimate compressive strength and micro-Vickers hardness of Al-1BN-0.15GNPs was obtained as ~ 225% and ~ 87% in comparison with those of pure aluminum. As a result, the mechanical properties of Al-BN-GNP hybrid composites were improved up to 1%BN and 0.15%graphene contents. Over these contents, the mechanical strength deteriorated due to the clumping of GNPs and nano-BN particles.

Solving Gravimetric-Volumetric Capacitive Paradox of 2D Materials through Dual-Functional Chemical Bonding-Induced Self-Constructing Graphene-MXene Monoliths.

High electrical conductivity and all-open microstructure characteristics intrinsically endow both graphene and MXenes with superior electrochemical energy storage capability. However, the above two-dimensional (2D) thicker electrodes (>20 μm) severely dilute their unique rapid electronic-ionic transferring characteristic, posing a paradox of high gravimetric and high volumetric capacitive properties due to massively excessive macropores or an unduly restacked issue. Herein, we elaborately construct novel monolithic NH2-graphene and Ti3C2Tx MXene (NG@MX) composites through dual-functional induced self-assembly with the help of both covalent and hydrogen bonding interactions. Notably, much thicker monolithic NG@MX electrodes (>90 μm) fabricated by a conventional roll-coating method without any further compaction treatment can simultaneously deliver two times gravimetric (gra.) and volumetric (vol.) performance than those of pure graphene (in vol.) or MXene (in gra.) materials. Moreover, monolithic NG@MX-based supercapacitors can remarkably present two times energy density as that of graphene and four times as MXene, respectively. Such greatly enhanced electrochemical properties are closely related to the appropriate equilibrium of the volumetric density and the open structure, which can effectively guarantee the rapid transfer of both electrons and ions in the thick monolithic NG@MX electrodes. Undoubtedly, dual-functional chemical bonding-induced self-constructing NG@MX monoliths efficiently solve the long-existing gra. and vol. capacitive paradox of the thicker 2D materials used in supercapacitors, which will guide the design of high-performance capacitive materials and promote their practical application in electrochemical energy storage.

Assessment of the Efficiency, Environmental and Economic Effects of Compact Type On-Site Wastewater Treatment Plants—Results from Random Testing

This study presents the results of random testing of selected on-site wastewater treatment plants (WWTPs) constructed in Poland in Masovia Voivodship in the years 2011–2016. The vast majority of tested on-site WWTPs were compact (container) type treatment plants, based on low rate activated sludge (AS), sequencing batch reactors (SBR), or a hybrid (activated sludge supported with biological film, AS + BF) method. Compact type plans are becoming more and more popular in single households in Poland, due to the option of co-financing. According to certificates provided by producers and distributors, container on-site wastewater treatment plants are efficient in BOD5 removal, with the expected removal rate being over 80%. The aim of this study was (1) to analyze BOD5 in effluents sampled from randomly selected on-site WWTPs, (2) to evaluate predicted and real environmental effects of the implementation of on-site WWTPs in selected communes within Masovia Voivodship, and (3) to calculate unit environmental and economic effects of container on-site WWTPs in three different technologies. Results of this study show that in most cases, there is a gap between the declared and the real BOD5 removal efficiency. There is also a difference between the performance of different container type technologies. The lowest real environmental effect was obtained for AS technology, and the highest for the hybrid one. The predicted environmental effect has only been almost achieved in the case of hybrid systems. Based on net present value (NPV) benefits, technologies can be set up as follows: AS &gt; SBR &gt; AS + BF, making the AS method the most effective technology from the point of view of the economy.

Use of a nitrification inhibitor reduces nitrous oxide (N2O) emissions from compacted grassland with different soil textures and climatic conditions

Grassland accounts for 70 % of the global agricultural area. Grassland amended with N fertiliser, although increasing productivity, encourages the emission of the greenhouse gas nitrous oxide (N2O). Soil compaction can result in impeded water movement and the development of anaerobic conditions that favour N2O production and emissions from denitrification. Soil compaction has become more prevalent in grassland with the use of increasingly heavy machinery and the extension of seasonal animal grazing periods, especially when soil moisture is high; close to field capacity. The effect of a nitrification inhibitor - dicyandiamide (DCD) on emissions of N2O from grassland moderately compacted from animal trampling or a tractor were investigated at two experimental field sites in the UK; a silt clay loam soil in a wet climate (SRUC) and a sandy loam in a drier climate (HAU). Compaction treatments repeated annually over three years (2011–2013) gave an overall increase in soil bulk density for the tractor compaction and animal trampling at both sites but to different degrees related to soil texture. Cumulative N2O emissions from tractor compaction for both SRUC and HAU were significantly greater than from the uncompacted control over the three years, with changing climate, soil texture and soil pH influencing the magnitude of N2O emissions. The use of DCD decreased cumulative N2O emissions at both sites, with the reduction greatest under tractor compaction, especially for the drier, sandier soil with the greater porosity. DCD appeared to decrease soil nitrate (NO3−) concentrations and decreased potential NO3− losses from leaching and run-off. Extrapolating from these data, the presence of moderate compaction, as identified in grasslands in England and Wales, could result in an estimated annual increase in N2O emissions of between 0.10 and 0.78 Mt of N2O, but these emissions could be reduced by up to 16 % and 51 % through the use of DCD, depending on compaction depth and soil texture. Although no yield increases were seen from the use of the DCD at both sites, N2O emissions were reduced.

Compaction and Heat Treatment Effects on the Structural and Mechanical Properties of Sintered Fe&lt;sub&gt;3&lt;/sub&gt;C-W-Co Alloys

In this article, the 75Fe3C-20W-5Co alloy is developed by the powder metallurgy technique in order to study the microstructure and the mechanical properties obtained after solid phase sintering. The mechanical grinding of the mixture of these Fe3C-W-Co powders lasted 6 hours.The powders were compressed by cold isostatic pressing (CIP) at different compaction pressures (5MPa, 10MPa, 15MPa and 18MPa). The green compacts obtained were sintered at a temperature equal to 1350 °C, followed by a heat treatment at different temperatures (850 °C, 950 °C and 1100 °C). The samples were then cooled in different baths (oil and water). The characterization of this sintered steel alloy was carried out by X-ray diffraction (XRD) and with an optical microscope. The results reveal that the structure of these sintered alloys consisted of the Fe matrix phase and the W-Co solid solution phase. The compaction pressure influences the number and size of the pores. Hardness and wear resistance increase with increasing compaction pressure.