PA12 nylon dust reduction of selective laser sintering reprocessing by optimization of refresh rate and powder handling

In this work, a novel composite adsorbent from coconut activated shell carbon (CAC), green mussel shell (GMS) and natural zeolite (ZEO) binding with ordinary Portland cement (OPC) were investigated over a range of two problematic parameters as known as ammoniacal nitrogen (NH3-N) and COD. The optimum conditions for adsorption in the batch study occurred at pH 7, shaking speed of 200 rpm, contact time of 120 min, adsorbent dosage of 5g and particle size of 2.36–3.35 mm. The adsorption isotherm behavior was investigated using Langmuir and Freundlich model, while adsorption kinetic behavior was investigated using Pseudo-first- and second-order model. The column adsorption experiment were conducted to investigate the varying effect of flowrate of (1.5, 2.0, 2.5 and 3.0 mL/min). The kinetics of adsorption were studied using Thomas, Adam Bohart and Yoon-Nelson model. The composite adsorbents were further tested for regeneration over five adsorption-desorption generation cycles. Based on the finding results, the best optimum ratio towards NH3-N and COD removal from leachate was achieved i-e, CAC 2.5g, GMS 1.5g and ZEO 1g respectively. The determination of isotherm adsorption describe the experimental result found better suited to the Langmuir isotherm. This composite adsorbents mainly shows monolayer adsorption coverage was predominant. Conversely, the kinetic adsorption obeyed well the second-order kinetic model that describe sorption process rate were controlling by the second-order kinetic model mechanism (chemisorption). Column adsorption result describes that the percentage removal of NH3-N and COD was achieved up to 99.78% at lower flowrate 1.5 mL/min which indicates in longer break-through and exhaustion times. Meanwhile, the adsorption experiment data fitted well-established with column adsorption model, namely, Thomas, Adam Bohart and Yoon-Nelson model. The finding results revealed that Thomas and Yoon-Nelson model found better suited as compared with Adam Bohart model. In conclusion, this research has successfully proven that the composite adsorbent is a suitable adsorbent for removal percentage of NH3-N and COD from landfill leachate

Empirical analysis of rough set categorical clustering techniques based on rough purity and value set

Clustering a set of objects into homogeneous groups is a fundamental operation in data mining. Recently, attention has been put on categorical data clustering, where data objects are made up of non-numerical attributes. The implementation of several existing categorical clustering techniques is challenging as some are unable to handle uncertainty and others have stability issues. In the process of dealing with categorical data and handling uncertainty, the rough set theory has become well-established mechanism in a wide variety of applications including databases. The recent techniques such as Information-Theoretic Dependency Roughness (ITDR), Maximum Dependency Attribute (MDA) and Maximum Significance Attribute (MSA) outperformed their predecessor approaches like Bi-Clustering (BC), Total Roughness (TR), Min-Min Roughness (MMR), and standard-deviation roughness (SDR). This work explores the limitations and issues of ITDR, MDA and MSA techniques on data sets where these techniques fails to select or faces difficulty in selecting their best clustering attribute. Accordingly, two alternative techniques named Rough Purity Approach (RPA) and Maximum Value Attribute (MVA) are proposed. The novelty of both proposed approaches is that, the RPA presents a new uncertainty definition based on purity of rough relational data base whereas, the MVA unlike other rough set theory techniques uses the domain knowledge such as value set combined with number of clusters (NoC). To show the significance, mathematical and theoretical basis for proposed approaches, several propositions are illustrated. Moreover, the recent rough categorical techniques like MDA, MSA, ITDR and classical clustering technique like simple K-mean are used for comparison and the results are presented in tabular and graphical forms. For experiments, data sets from previously utilized research cases, a real supply base management (SBM) data set and UCI repository are utilized. The results reveal significant improvement by proposed techniques for categorical clustering in terms of purity (21%), entropy (9%), accuracy (16%), rough accuracy (11%), iterations (99%) and time (93%). vi

Utilization of wastewater treatment sludge in the production of fired clay bricks: An approach towards sustainable development

Wastewater treatment sludge has increase due to the increasing of population and economic potential. Sludge generally contains heavy metals that could lead to environmental effect as well as to human health. This study is focus on utilization of sludges into incorporated fired clay brick. The samples of sludge were gathered from IWK in Perwira and Senggarang. The heavy metal concentration in the wastewater treatment sludge was identified using X-Ray Fluorescence. Sludges were incorporated into bricks at various percentages: 0 %, 1 %, 5 %, 10 %, 20 %, and 30 %. The physical and mechanical characteristics of brick after being integrated with both types of sludges were identified. Furthermore, heavy metals leachability of sludge bricks was tested. The findings reveal that Barium (Ba) has the highest heavy metal concentration in the raw materials, and the chemical composition is Silicon Dioxide (SiO2). Bricks with 5 % sludge content exhibited optimal physical and mechanical attributes for both sludge types. However, sludge from Senggarang exhibited the better results compared to Perwira sludge. In terms of leachability, heavy metals were analysed in bricks from both sludge types. Bricks containing up to 20 % sludge from Senggarang exhibited the lowest heavy metal leachability. Nevertheless, value of heavy metals from both sludges is complied with USEPA standard. In conclusion, 5 % of both sludges is the best percentage to be utilized into fired clay brick by considering it properties and leachability. This study also demonstrated that adopting cleaner production techniques for building bricks can make a substantial contribution towards attaining Sustainable Development Goals (SDGs)

Compressive Strength of Fired Clay Bricks Incorporated with Ceramic Sludge Industry

Sludge is created during a variety of industrial processes, including industrial ceramics. Considering sludge waste is often disposed of in landfills, the expense of treating sludge waste is becoming uneconomical, and landfill area is diminishing. The industrial ceramics sludge has been identified as a potential alternative ingredient in making bricks. In this research, the optimum percentage of ceramic industry sludge incorporation with fired clay is determined according to its physical properties in order to improved compressive strength in fired clay brick. From the result shows that by incorporation of 30% of ceramic sludge into fired clay brick complied with the British Standard (BS) requirement and Eco-Labelling criteria in SIRIM ECO 023:2016 for building material usage. Therefore, ceramic sludge can be material for brick production with appropriate mix and design and as an alternative substitution of reasonable material that offers eco-friendly disposal method

Assessment of thermal conductivity and indoor air quality of fired clay brick incorporated with electroplating sludge

Industrial activity is one of the main contributors in developing and growth of economy in Malaysia. Industries and agricultures in Malaysia, generate harmful waste which, if not properly disposed of can damage to landfills and the environment. Brick is one of an important masonry unit needed as building materials. This paper addresses the thermal conductivity and Indoor Air Quality (IAQ) when the fired clay bricks are combined with electroplating sludge (ES). The fired clay bricks were examined using five different ratios 2%, 4%, 6%, 8% and 10%. The X-ray Fluorescence (XRF) result showed that the highest percentage of electroplating sludge composition was aluminium oxide (Al2O3) which is 67.20%. The clay soil showed that the highest percentage of silicon dioxide (SiO2) and aluminium oxide (Al2O3) which was 67.60% and 19.70%, respectively. The IAQ result of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), formaldehyde (HCHO) and particulate matter (PM10) of fired clay brick with 4% of electroplating sludge was acceptable and safe to be used as building material as it had the most lower gas emissions and compared to the control brick with 0% of sludge. Moreover, all parameters in every pattern did not have much contrast with the limit by Industry Code of Practice on Indoor Air Quality (ICOP-IAQ) standard. Therefore, electroplating sludge an alternative low-cost material that provides an environmentally friendly disposal method

Electric field and space charge characteristics of xlpe insulation doped with nanofillers

Various types of nanoparticles had been introduced as additive to polymeric insulator by previous researchers. As a result, the existence of nanometre-size particles is well acknowledged in enhancing the dielectric strength in insulation material. The remained unanswered that is concerning the nanometre-sizes in maximising the potential of nanocomposite insulator. The main criteria to dictate the dielectric performance is by measuring the level of electric field distribution. While, electric field properties also influenced by the accumulation amount of space charge. So, this study was conducted to evaluate the electric field and space charge distribution in within nanocomposite insulator. The primary purpose is to identify the finest size in each type of selected nanoparticles in optimising the dielectric properties, but selecting the best type of nanofillers as well. Three different sizes attributed from 100nm, 80nm and 50nm were selected from three different nanofillers which are nanometre silicon dioxide (NSD), nanometre titanium dioxide (NTD) and air. All these nanofillers were doped in XLPE separately for simulation based study. Electric field distribution and space charge tabulation on each selected size were measured and compared. Consequently, each type of nanofillers give a selection different of sizes for the best dielectric performance. Conclusively, the best size for NSD, NTD and air were 100nm, 80nm and 50nm respectively. The dominant influence of nanometre-size is the intrinsic behaviour of an oxidised element in nanofillers. In term of type, NTD is performed in electric field distribution can correlated with its permittivity constant, ε. But for space charge tabulation, NSD is better due its intrinsic behaviour and insulation structure