Integrated approach as sustainable environment technique for managing construction waste : a review

The construction industry was reported as a major consumer of natural resources worldwide. Almost 60% of the natural resources consumed by this industry have caused a lot of environmental impacts on humans and the environment. Among the impacts were the disruption of human water sources, changes in the biological ecosystem and disruption of the food supply chain among biological factors. Countries around the world have enforced several laws and regulations. Apart from that, waste management technologies were formulated by government agencies and the world’s researchers were among initiatives to minimise the waste generation rate. Several technologies, such as recycling and recovery technologies were highlighted to be very efficient in minimising the waste accumulation rate. This paper discussed an integrated concept for managing construction waste in a sustainable manner. The integrated approach has adopted the reuse method, central sorting facilities, recycling facilities, thermal treatment facilities and disposal facilities. Implementations of these integrated approaches were able to save the world’s raw materials and natural energy sources as well as reducing the impacts of pollution on the environment

Performance of an innovative multi-stage anaerobic reactor during start-up period

Start-up of an anaerobic reactor is a relatively delicate process and depends on various factors such as wastewater composition, available inoculum, operating conditions and reactor configuration. Accordingly, systematized operational procedures are important, mainly during the start-up of an anaerobic reactor. In this paper, the start-up performance of an innovative multi-stage anaerobic reactor using synthetic wastewater at various organic loading rates (OLRs) was investigated. In Phase 1 of the experimental study, the reactor was operated at hydraulic retention time (HRT) of 1 day with corresponding OLR of 1.07 kg COD.m-3.d-1. Thereafter, the reactor was operated at intermittent feeding (Phase 2), with HRT of 1.4 day and OLR of 0.82 to 2.45 kg COD.m-3.d-1. Results showed up to 71% COD reduction in the Phase 1 of the experimental study. However, in Phase 2, when the reactor was operated at intermittent feeding, the COD removal efficiency increased from 75 to 92%. It can be concluded that the multi-stage anaerobic reactor system performed better at intermittent feeding, indicating that the reactor required low loading rate and sufficient HRT for gradual acclimatization for reactor start-up. The reduction of the period necessary for the start-up and improved operational control are important factors to increase the efficiency the reactor system.Key words: Anaerobic reactor start-up, biomass, glucose wastewater, intermittent feeding, multi-stage anaerobic reactor

Treatment of wastewater using response surface methodology: a brief review

Response surface methodology (RSM) is widely applied to gathering knowledge on the interactions among parameters that require optimization during the treatment of wastewater. It can be used to optimize parameters during the process of treating wastewater, e.g., landfill leachate. The experimental design methods are useful to evaluate the parameters involved in a treatment with the minimum number of experiments. This will reduce the need for reagents and materials for experiments, which finally causes both time and expense to be increased. Anaerobic digestion of wastewater technologies escalated depending on the design configuration of the reactor. Several important parameters are taken into consideration in designing an anaerobic reactor such as operating conditions, seed sludge, wastewater composition and mixing. To construct a highly efficient degradation system, it is necessary to optimize such effective parameters. As a result, the advanced statistical design is used for process characterization, optimization and modelling. In this paper, the fundamentals of RSM and its application in the anaerobic treatment of wastewater was discussed in brief. The various works done in an anaerobic reactor using RSM for prediction and optimization are given

Prediction and optimization of the Fenton process for the treatment of landfill leachate using an artificial neural network

In this study, the artificial neural network (ANN) technique was employed to derive an empirical model to predict and optimize landfill leachate treatment. The impacts of H2O2:Fe2+ ratio, Fe2+ concentration, pH and process reaction time were studied closely. The results showed that the highest and lowest predicted chemical oxygen demand (COD) removal efficiency were 78.9% and 9.3%, respectively. The overall prediction error using the developed ANN model was within -0.625%. The derived model was adequate in predicting responses (R2 = 0.9896 and prediction R2 = 0.6954). The initial pH, H2O2:Fe2+ ratio and Fe2+ concentrations had positive effects, whereas coagulation pH had no direct effect on COD removal. Optimized conditions under specified constraints were obtained at pH = 3, Fe2+ concentration = 781.25 mg/L, reaction time = 28.04 min and H2O2:Fe2+ ratio = 2. Under these optimized conditions, 100% COD removal was predicted. To confirm the accuracy of the predicted model and the reliability of the optimum combination, one additional experiment was carried out under optimum conditions. The experimental values were found to agree well with those predicted, with a mean COD removal efficiency of 97.83%

The evolution of green shipping practices adoption in the international maritime industry

Seaborne trade exhibits a continual expansion with technological advancement, reportedly 10.7 billion tons in 2017, with a 3.8% growth annually. It is forecast to double in the next two decades (UNCTAD, 2018). The International Maritime Organization (IMO) is persistently heading to stricter regulatory amendments to steer shipping towards a greener and more sustainable future. Therefore, green shipping has drawn enormous interest from both academia and researchers. This paper summarizes a comprehensive bibliometric analysis aiming to understand the development of research trends in this area and suggest future research. Most of the research is focused on air pollution, practical operation or technical measures, recycling for GSP in the shipping sector. The theoretical approach to GSP and its concept is yet to be crystalline for the marine industry. According to existing research, further study is required to establish a GSP construct and propose pollution abatement technical solutions with a comprehensive evaluating tool. Besides, scholars from different territories may collaboratively suggest setting up standards and legislation of GSP for the life cycle of the ship to achieve an ever-sustainable maritime transport industry worldwide

Elucidation and characterization of new chlorinated by-products after electrochemical degradation of hydrochlorothiazide using graphite poly vinyl chloride electrode

This paper describes an electrochemical treatment process of hydrochlorothiazide (HDZ) under different conditions such as initial concentration, sodium chloride and applied voltage. In this present study, HDZ was treated by electrochemical oxidation process using graphite-PVC composite electrode as anode and Platinum (Pt) as cathode. All results were analyzed using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). It was found that at high applied voltages, and high amounts of NaCl, the electrochemical treatment process was more efficient. The removal% of HDZ was 92% at 5 V after 60 min. From the obtained results, the electrochemical oxidation process of HDZ followed pseudo first order with rate constant values ranged between 0.0009 and 0.0502 min−1, depending on the experimental conditions. Energy consumption was also considered in this study, it was ranged between 0.9058 and 5.56 Wh/mg using 0.5, 0.3 and 0.1 g NaCl within interval times of (10, 20, 30, 40, 50, 60, 70, and 80 min). Five chlorinated and one non-chlorinated by-products were formed and analyzed in negative ionization (NI) mode during the electrochemical process. Due to the strong oxidizing potential of the chlorine (Cl2) and hypochlorite ion (ClO−), HDZ and its by-products were removed after 140 min. Furthermore, a novel synthesis of chlorothiaizde as one of the new by-products was reported in this present study. Toxicity was impacted by the formation of the by-products, especially at 20 min. The inhibition percentage (I%) of E. coli bacteria was decreased to be the lowest value after 140 min

Effect of covid-19 virus on reducing GHG emission and increasing energy generated by renewable energy sources: a brief study in Malaysian context

Coronavirus 2019 (COVID-19) has globally affected the human mortality rate and economic history of the modern world. According to the World Health Organization, COVID-19 has caused a severe threat to the health of the vulnerable groups, notably the elderly. There is still some disagreements regarding the source of the virus and its intermediate host. However, the spread of this disease has caused most countries to enforce strict curfew laws and close most industrial and recreational centres. This study aims to show the potential positive effects of COVID-19 on the environment and the increase of renewable energy generation in Malaysia. To prevent the spread of this disease, Malaysia enacted the Movement Control Order (MCO) law in March 2020. Implementation of this law led to a reduction in environmental pollution, especially air pollution, in this country. The greenhouse gases (GHG) emission , which was 8 Mt CO2 eq. from January 2020 to March 2020, reduced to <1 Mt CO2 eq. for April and May. The reduction of GHG emission and pollutant gases allowed more sunlight to reach photovoltaic panels, hence increasing the renewable energy generation