The degradation of (RS)-MCPP was investigated in an anaerobic membrane bioreactor (AnMBR) using nitrate as an available electron acceptor under different COD/NO(3)(-)-N ratios. Results showed high soluble COD removal efficiency (80-93%) when the reactor was operated at high COD/NO(3)(-)-N ratios. However, the COD removal started to decline (average 15%) at high nitrate concentrations coinciding with a drop in nitrate removal efficiency to 37%, suggesting that the denitrification activity dropped and affected the AnMBR performance when nitrate was the predominant electron acceptor. Additionally, the removal efficiency of (RS)-MCPP increased from 2% to 47% with reducing COD/NO(3)(-)-N ratios, whilst the (RS)-MCPP specific utilisation rate (SUR) was inversely proportional to the COD/NO(3)(-)-N ratio, suggesting that a lower COD/NO(3)(-)-N ratios had a positive influence on the (RS)-MCPP SUR. Although nitrate had a major impact on methane production rates, the methane composition was stable (approximately 80%) for COD/NO(3)(-)-N ratios of 23 or more.
Tylosin has been considered inhibiting COD removal in anaerobic digestion. In this study it is proven that this is not always the case. Accordingly, elevated concentrations of Tylosin (100-800mgL-1) could be tolerated by the anaerobic system. The influence of Tylosin concentrations on an up-flow anaerobic stage reactor (UASR) was assessed using additions of Tylosin phosphate concentrate. Results showed high efficiency for COD removal (average 93%) when Tylosin was present at concentrations ranging from 0 to 400 mg L-1. However, at Tylosin concentrations of 600 and 800 mg L-1 treatment efficiency declined to 85% and 75% removal respectively. The impact of Tylosin concentrations on archaeal activity were investigated and the analysis revealed that archaeal cells dominated the reactor, confirming that there was no detectable inhibition of the methanogens at Tylosin levels between 100 and 400mg L-1. Nevertheless, the investigation showed a slight reduction in the number of methanogens at Tylosin levels of 600 and 800 mg L-1. These results demonstrated that the methanogens were well adapted to Tylosin. It would not be expected that the process performance of the UASR would be affected, not even at a level well in excess of those appearing in real wastewater from a Tylosin production site.
The effects of different hydraulic retention time (HRT) on (RS)-MCPP utilisation was investigated by decreasing the feed flow rate in an anaerobic membrane bioreactor (AnMBR). Results showed an average COD removal efficiency of 91.4%, 96.9% and 94.4% when the reactor was operated at HRT 3, 7 and 17 d, respectively. However, when the HRT was reduced to 1d, the COD removal efficiency declined to just only 60%, confirming the AnMBR is stable to a large transient hydraulic shock loads. The (RS)-MCPP removal efficiency fluctuated from 6% to 39% at HRT 3 d, however when it was increased to 7 and 17 d, the removal efficiency increased to an average of 60% and 74.5%. In addition, (RS)-MCPP specific utilisation rates (SUR) were dependent on the HRT and gradually improved from 18 to 43 μg mg VSS(-1) d(-1) as flow rate increased.
The effects of Mecoprop (RS)-MCPP were investigated in an anaerobic membrane bioreactor (AnMBr) fed with synthetic wastewater containing stepwise increases in Mecoprop concentration, 5-200 mg L(-1) over 240 days. Effects were observed in terms of soluble chemical oxygen demand (COD) removal efficiency, volatile fatty acid (VFA) production, and methane yield. Soluble COD removal efficiency was stable at Mecoprop concentrations below 200 (±3) mg L(-1), with an average of 98 (±0.7)% removal. However, at 200 (±3) mg L(-1) Mecoprop, the COD removal efficiency decreased gradually to 94 (±1.5)%. At 5 mg L(-1) Mecoprop, acetic and propionic acid concentrations increased by 60% and 160%, respectively. In contrast, when Mecoprop was increased to 200 (±3) mg L(-1), the formation and degradation of acetate was unaffected by the higher Mecoprop concentration, acetate remaining below 35 mg L(-1). Increases in the Mecoprop specific utilization rate were observed as Mecoprop was increased stepwise between 5 and 200 mg L(-1).
Water pollution during festival periods is a major problem in all festival cities across the world. Reliable prediction of water pollution is essential in festival cities for sewer and wastewater management in order to ensure public health and a clean environment. This article aims to model the biological oxygen demand (BOD(5)), and total suspended solids (TSS) parameters in wastewater in the sewer networks of Karbala city center during festival and rainy days using structural equation modeling and multiple linear regression analysis methods. For this purpose, 34 years (1980-2014) of rainfall, temperature and sewer flow data during festival periods in the study area were collected, processed, and employed. The results show that the TSS concentration increases by 26-46 mg/l while BOD(5) concentration rises by 9-19 mg/l for an increase of rainfall by 1 mm during festival periods. It was also found that BOD(5) concentration rises by 4-17 mg/l for each increase of 10,000 population.
This paper investigates the optimum operational conditions of a novel rotated bed electrocoagulation (EC) reactor for the treatment of textile wastewater. The effect of various operational parameters such as rotational speed, current density (CD), operational time (RT), pH, temperature, and inter-electrode distance (IED) on the pollutant removal efficiency were examined. In addition, the consumption of aluminum (Al) and electrical energy, as well as operating costs at optimum conditions were also calculated. The results indicated that the optimum conditions for the treatment of textile wastewater were achieved at CD = 4 mA/cm(2), RT = 10 min, rotational speed = 150 rpm, pH = 4.57, temperature = 25 °C, and IED = 1 cm. The electrode consumption, energy consumption, and operating costs were 0.038 kg/m(3), 4.66 kWh/m(3) and 0.44 US$/m(3), respectively. The removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solid (TSS), turbidity and color were 97.10%, 95.55%, 98%, 96% and 98.50%, respectively, at the first 10 min of reaction time, while the phenol compound of the wastewater was almost entirely removed (99.99%). The experimental results confirm that the new reactor design with rotated anode impellers and cathode rings provided high treatment efficiency at a reduced reaction time and with lower energy consumption.
Strict environmental concerns, depleting natural recourses, and rising demand for building construction materials have promoted scientific research toward alternative building materials. This research supports the idea of sustainability and a circular economy via the utilization of waste to produce value-added products. The research explored the potential of waste plastics and silica sand for developing thermoplastic composite as floor tiles. The samples were characterized by water absorption, compressive strength, flexural strength, and sliding wear. The morphological analysis of the sand-plastic interfaces was covered under the umbrella of this study. The maximum compressive and flexural strength were found to be 46.20 N/mm2 and 6.24 N/mm2, respectively, with the minimum water absorption and sliding wear rate of 0.039% and 0.143 × 10-8 kg/m, respectively. The study suggests the workability of the developed floor tiles in non-traffic areas of public places. Thus, the study provides a green building material through recycling waste plastics for sustainable development.
This study was to develop biogranules using a sequencing batch reactor (SBR) and to evaluate the effect of pineapple wastewater (PW) as a co-substrate for treating real textile wastewater (RTW). The biogranular system cycle was 24 h (2 stages of phase), with an anaerobic phase (17.8 h) followed by an aerobic phase (5.8 h) for every stage of the phase. The concentration of pineapple wastewater was the main factor studied in influencing COD and color removal efficiency. Pineapple wastewater with different concentrations (7, 5, 4, 3, and 0% v/v) makes a total volume of 3 L and causes the OLRs to vary from 2.90 to 0.23 kg COD/m3day. The system achieved 55% of average color removal and 88% of average COD removal at 7%v/v PW concentration during treatment. With the addition of PW, the removal increased significantly. The experiment on the treatment of RTW without any added nutrients proved the importance of co-substrate in dye degradation.
The influence of hydraulic retention time (HRT, 24, 12, and 6h) on the physical characteristics of granules and performance of a sequencing batch reactor (SBR) treating rubber wastewater was investigated. Results showed larger granular sludge formation at HRT of 6h with a mean size of 2.0±0.1mm, sludge volume index of 20.1mLg(-1), settling velocity of 61mh(-1), density of 78.2gL(-1) and integrity coefficient of 9.54. Scanning electron microscope analyses revealed different morphology of microorganisms and structural features of granules when operated at various HRT. The results also demonstrated that up to 98.4% COD reduction was achieved when the reactor was operated at low HRT (6h). Around 92.7% and 89.5% removal efficiency was noted for ammonia and total nitrogen in the granular SBR system during the treatment of rubber wastewater.
Phosphate-free spray dried detergent powders (SDDP) comprising binary anionic surfactants of palm C16 methyl ester sulfonate (C16MES) and linear alkyl benzene sulfonic acid (LABSA) were produced using a 5 kg/h-capacity co-current pilot spray dryer (CSD). Six phosphate-free detergent (PFD) formulations comprising C16MES/LABSA in various ratios under pH 7-8 were studied. Three PFD formulations having C16MES/LABSA in respective ratios of 0:100 (control), 20:80 and 40:60 ratios were selected for further evaluation based on their optimum detergent slurry concentrations. The resulting SDDP from these formulations were analysed for its detergency stability (over nine months of storage period) and particle characteristics. C16MES/LABSA of 40:60 ratio was selected as the ideal PFD formulation since its resulting SDDP has consistent detergency stability (variation of 2.3% in detergency/active over nine months storage period), excellent bulk density (0.37 kg/L), fine particle size at 50% cumulative volume percentage (D50 of 60.48 μm), high coefficient of particle size uniformity (D60/D10 of 3.86) and large spread of equivalent particle diameters. In terms of surface morphology, the SDDP of the ideal formulation were found to have regular hollow particles with smooth spherical surfaces. Although SDDP of the ideal formulation have excellent characteristics, but in terms of flowability, these powders were classified as slightly less free flowing (Hausner ratio of 1.27 and Carr's index of 21.3).
The present study demonstrated that aerobic granular sludge is capable of treating livestock wastewater from a cattle farm in a sequencing batch reactor (SBR) without the presence of support material. A lab scale SBR was operated for 80 d using 4 h cycle time with an organic loading rate (OLR) of 9 kg COD m(-3) d(-1). Results showed that the aerobic granules were growing from 0.1 to 4.1 mm towards the end of the experimental period. The sludge volume index (SVI) was 42 ml g(-1) while the biomass concentration in the reactor grew up to 10.3 g L(-1) represent excellent biomass separation and good settling ability of the granules. During this period, maximum COD, TN and TP removal efficiencies (74%, 73% and 70%, respectively) were observed in the SBR system, confirming high microbial activity in the SBR system.
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.
Inadequately treated or untreated wastewater greatly contribute to the release of unwanted toxic contaminants into water bodies. Some of these contaminants are persistent and bioaccumulative, becoming a great concern as they are released into the environment. Despite the abundance of wastewater treatment technologies, the adsorption method overall has proven to be an excellent way to treat wastewater from multiple industry sources. Because of its significant benefits, i.e., easy availability, handling, and higher efficiency with a low cost relative to other treatments, adsorption is opted as the best method to be used. However, biosorption using naturally found seaweeds has been proven to have promising results in removing pollutants, such as dyes from textile, paper, and the printing industry, nitrogen, and phosphorous and phenolic compounds, as well as heavy metals from various sources. Due to its ecofriendly nature together with the availability and inexpensiveness of raw materials, biosorption via seaweed has become an alternative to the existing technologies in removing these pollutants from wastewater effectively. In this article, the use of low-cost adsorbent (seaweed) for the removal of pollutants from wastewater has been reviewed. An extensive table summarises the applicability of seaweed in treating wastewater. Literature reported that the majority of research used simulated wastewater and minor attention has been given to biosorption using seaweed in the treatment of real wastewater.
The sol-gel/ultrasonically rout produced the novel MnS2-SiO2 nano-hetero-photocatalysts with the various ratio of MnS2. Prepared nano-catalyst were investigated in the photo-degradation of methylene blue under UV light illumination. Structural and optical attributes of as-prepared nano-catalysts were evaluated by X-ray diffraction and photoelectron spectroscopy. The morphological were studied by scanning electron microscopy-EDS, and dynamic light scattering. The diffuse reflectance spectroscopy was applied to examine the band gap energy. The Eg values of SiO2, MnS2-SiO2-0, MnS2-SiO2-1, and MnS2-SiO2-2 nanocomposites are 6.51, 3.85, 3.17, and 2.67 eV, respectively. The particle size of the SiO2 and MnS2-SiO2-1 nanocomposites were 100.0, and 65.0 nm, respectively. The crystallite size values of MnS2-SiO2-1 were 52.21 nm, and 2.9 eV, respectively. MnS2-SiO2 nano-photocatalyst was recognized as the optimum sample by degrading 96.1% of methylene blue from water. Moreover, the influence of pH of the solution, and contact time as decisive factors on the photo-degradation activity were investigated in this project. The optimum data for pH and time were found 9 and 60 min, respectively. The photo-degradation capacity of MnS2-SiO2-2 is improved (96.1%) due to the low band gap was found from UV-vis DRS. The antimicrobial data of MnS2-SiO2 were studied and demonstrated that the MnS2-SiO2 has fungicidal and bactericidal attributes.
NiS-SiO2 and Cr2S3-TiO2 synthesized by Ultrasound-Microwave method was tested for the photo-degradation of methyl red as azo dye under ultraviolet (UV) light. The structure and morphology of the synthesized materials were examined through scanning electron microscopy, X-ray diffraction and photoelectron spectroscopy, energy-dispersive spectroscopy, dynamic light scattering and the band gap energy differences were determined through diffuse reflectance spectroscopy (DRS). The crystallite size and band gap values of SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were obtained from XRD and UV-vis DRS analysis and found insignificant 44.22, 54.11, and 57.11 nm, and 8.9, 3.2, 3.0, 2.7 eV, respectively. The NiS-SiO2 and Cr2S3-TiO2 nanocomposites exhibited good stability and catalytic performance in the azo dye degradation; the composite provides a complete degradation after 50 min under UV irradiation. The effects of different quencher compounds on the Methyl red dye degradation were also investigated. The result for this experiment shows the system without the quencher was highly degradation of Methyl red. The antibacterial influence of the SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were studied versus two species bacteria. The antifungal performance of this nanoparticle was analyzed versus two species fungi as the C. albicans and P. funiculosum. Biological data demonstrated that the prepared catalyst has great bactericidal and fungicidal properties.
Recent years have seen issues related to thermal comfort gaining more momentum in tropical countries. The thermal adaptation and thermal comfort index play a significant role in evaluating the outdoor thermal comfort. In this study, the aim is to capture the thermal sensation of respondents at outdoor environment through questionnaire survey and to determine the discomfort index (DI) to measure the thermal discomfort level. The results indicated that most respondents had thermally accepted the existing environment conditions although they felt slightly warm and hot. A strong correlation between thermal sensation and measured DI was also identified. As a result, a new discomfort index range had been proposed in association with local climate and thermal sensation of occupants to evaluate thermal comfort. The results had proved that the respondents can adapt to a wider range of thermal conditions.Validation of the questionnaire data at Putrajaya was done to prove that the thermal sensation in both Putrajaya and UTM was almost similar since they are located in the same tropical climate region. Hence, a quantitative field study on building layouts was done to facilitate the outdoor human discomfort level based on newly proposed discomfort index range. The results showed that slightly shaded building layouts of type- A and B exhibited higher temperature and discomfort index. The resultant adaptive thermal comfort theory was incorporated into the field studies as well. Finally, the study also showed that the DI values were highly dependent on ambient temperature and relative humidity but had fewer effects for solar radiation intensity.
The present study describes the phytoremediation performance of water lettuce (Pistia stratiotes L.) for physicochemical pollutants elimination from paper mill effluent (PME). For this, pot (glass aquarium) experiments were conducted using 0% (BWW: borewell water), 25%, 50%, 75%, and 100% treatments of PME under natural day/light regime. Results of the experiments showed that the highest removal of pH (10.75%), electrical conductivity (EC: 63.82%), total dissolved solids (TDS: 71.20%) biological oxygen demand (BOD: 85.03%), chemical oxygen demand (COD: 80.46%), total Kjeldahl's nitrogen (TKN: 93.03%), phosphorus (P: 85.56%), sodium (Na: 91.89%), potassium (K: 84.04%), calcium (Ca: 84.75%), and magnesium (Mg: 83.62%), most probable number (MPN: 77.63%), and standard plate count (SPC: 74.43%) was noted in 75% treatment of PME after treatment by P. stratiotes. PCA showed the best vector length for TKN, Na, and Ca. The maximum plant growth parameters including, total fresh biomass (81.30 ± 0.28 g), chlorophyll content (3.67 ± 0.05 mg g-1 f.wt), and relative growth rate (0.0051 gg-1 d-1 ) was also measured in 75% PME treatment after phytoremediation experiments. The findings of this study make useful insight into the biological management of PME through plant-based pollutant eradication while leftover biomass may be used as a feedstock for low-cost bioenergy production. PRACTITIONER POINTS: Biological treatment of paper mill effluent using water lettuce is presented. Best reduction of physicochemical and microbiological pollutants was attained in 75% treatment. Maximum production of chlorophyll, plant biomass, and highest growth rate was also observed in 75% treatment.
The presence of chloride ion as an environmental pollutant is having a devastating and irreversible effect on aquatic and terrestrial ecosystems. To ensure safe and clean drinking water, it is vital to remove this substance using non-toxic and eco-friendly methods. This study presents a novel and highly efficient Ag NPs-modified bentonite adsorbent for removing chloride ion, a common environmental pollutant, from drinking water using a facile approach. The surface chemical properties and morphology of the pristine Na-bentonite and Ag NPs-Modified bentonite were characterized by field emission scanning electron microscopy (FESEM) and X-ray spectroscopy (EDX), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), and zeta potential (ζ). To achieve maximum chloride ion removal, the effects of experimental parameters, including adsorbent dosage (1-9 g/L), chloride ion concentration (100-900 mg/L), and reaction time (5-25 h), were examined using the Response Surface Methodology (RSM). The chloride ion removal of 90% was obtained at optimum conditions (adsorbent dosage: 7 g/L, chloride ion concentration: 500 mg/L, and reaction time: 20 h). The adsorption isotherm and kinetics results indicated that the Langmuir isotherm model and pseudo-second-order kinetics were found suitable to chloride ion removal. Additionally, the regeneration and reusability of the Ag NPs-modified bentonite were further studied. In the regeneration and reusability study, the Ag NPs-modified bentonite has shown consistently ≥90% and ≥87% chloride ion removal even up to 2 repeated cycles, separately. Thus, the findings in this study provided convincing evidence for using Ag-NPs modified bentonite as a high-efficiency and promising adsorbent to remove chloride ion from drinking water.
Semiconductor metal oxide with TiO2 nanoparticles removes hazardous compounds from environmental samples. TiO2 nanoparticles have shown potential as an efficient photocatalyst by being employed as a nano-catalyst for the breakdown of organic contaminants in wastewater samples. To separate substances from contaminated samples, combined UV and visible light irradiation has been used. Sol-gel synthesis was used to produce a copper chromite-titanium nanocomposite, which was then evaluated using analytical methods, such as XRD, BET, DRS-UV, and FT-IR. Using visible light, the photocatalytic activity of a nanocomposite made of CuCr2O4 and TiO2 was investigated for its role in the breakdown of malachite green. The effects of several parameters, including pH change, anions presence, contact time, catalyst amount, concentration variation, and the kinetics of photocatalytic degradation were investigated. The magnitude of transition energy calculated using UV-DRS spectra was found to be 3.1 eV for CuCr2O4-TiO2 nanocomposite. Maximum degradation was observed at pH 7.0. The surface area and pore volume of the co-doped samples of Cr2O4 - TiO2 obtained from BET were found to be 6.1213 m2/g and 0.045063 cm3/g respectively. The average particle size of the catalyst of the nano-catalysts calculated from XRD was found to be 8 nm for TiO2 and 66 nm for TiO2-CuCrO4. The peaks obtained in FTIR between the range of 900-500 cm-1 were due to the presence of an aromatic compound. The binding mechanism of a dye molecule to the surface of CuCr2O4-TiO2 nanocomposite was analysed using quantum chemical calculations with the self-consistent reaction field technique employing integral equation formalism for the polarized continuum method and the UFF atomic radii set.
Fig leaf, an environmentally friendly byproduct of fruit plants, has been used for the first time to treat of methylene blue dye. The fig leaf-activated carbon (FLAC-3) was prepared successfully and used for the adsorption of methylene blue dye (MB). The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH solution, FLAC-3 dose, volume solution, and activation agent were investigated. However, the initial concentration of MB was investigated at different concentrations of 20, 40, 80, 120, and 200 mg/L. pH solution was examined at these values: pH3, pH7, pH8, and pH11. Moreover, adsorption temperatures of 20, 30, 40, and 50 °C were considered to investigate how the FLAC-3 works on MB dye removal. The adsorption capacity of FLAC-3 was determined to be 24.75 mg/g for 0.08 g and 41 mg/g for 0.02 g. The adsorption process has followed the Langmuir isotherm model (R2 = 0.9841), where the adsorption created a monolayer covering the surface of the adsorbent. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 41.7 mg/g and the Langmuir affinity constant (KL) was 0.37 L/mg. The FLAC-3, as low-cost adsorbents for methylene blue dye, has shown good cationic dye adsorption performance.