Differential response of Bruguiera cylindrica to individual (CuSO₄) and combined (CuSO₄ NaCl) effect was evaluated. The plantlets were treated with control, 0.15 mM CuSO₄, 400 mM NaCl and 0.15 mM CuSO₄ + 400 mM NaCl. Under combined stress, higher accumulation of Cu in the roots indicate that the roots are the primary site of Cu accumulation and thus the plant perform as an excluder and photosynthetic efficiency reduced drastically and significant enhancement in the superoxide and hydroxyl free radicals which increase membrane lipid peroxidation, leading to cellular damage and destruction. As evidenced from SEM-EDXMA, increase in Cu and Na⁺ levels in xylem and pith regions of leaf and stem and the presence of deeply stained structures, denoting the probable formation of complex containing the metal. Increased CaOx crystal forming cells (crystal idioblasts) reveals the regulation of bioaccumulated Cu and Na⁺ by complexing with CaOx. Thus the study suggested that, 400 mM NaCl and 0.15 mM CuSO₄ treatments does not have negative impact on plant growth, the NaCl tolerance potential compromised in the presence of mild CuSO₄ concentration during combined stress.

Nutriment distributions might influence Cd distribution and Cd tolerance in mangrove plant roots. To demonstrate this, Aegiceras corniculatum was stressed by Cd, and the distributions of Cd, Ca, P, Na and Cl in plant roots were detected with the aid of SEM-EDX. It was found that endodermis, pith and xylem were the predominant tissues for retardation and regional enrichment of Cd. Na and Cl distributions suggest a critical role of salt resistance tissues on Cd tolerance in roots. P participated in Cd retardation and regional enrichment of endodermis and xylem. P, Na, Cl and Ca distribution had a high correlation to that of Cd in roots. The synergetic accumulation between Ca and Cd could be a crucial mechanism for Cd tolerance in A. corniculatum roots. In conclusion, the research of Cd and nutriment distributions in A. corniculatum roots deepens the understanding on Cd tolerance in mangrove plants.

Microbiological activities are essential in the bioremediation of polluted soils. The enzymatic activities of microorganisms are usually used as a biological indicator of soil health. The aim of this work was to observe the catalase, acid phosphatase (AcP), and alkaline phosphatase (AlP) activities in soil that was amended with agro-industrial by-products and macronutrients during the process of total petroleum hydrocarbon (TPH) removal. To this end, microcosm tests were performed with soil and agro-industrial by-products ratios of 100:2:2, for soil:sugarcane bagasse pith:filter cake mud (SSF); 100:2, for both soil:sugarcane bagasse pith (SS); and for soil filter cake mud (SF). The macronutrients—carbon, nitrogen, and phosphorus—in the experimental treatments were adjusted to 100:10:1 with a solution of NH₄NO₃ and K₂HPO₄. The best TPH removal (51.4%) was obtained with SSF at 15 days. In addition, a significant correlation was observed between TPH removal and AlP as well as AcP (r = 0.74, p < 0.0001; r = 0.70, p < 0.0107, respectively). Fungi growth was also correlated with both AlP (r = 0.97, p < 0.0001) and AcP (r = 0.95, p < 0.0001) activities. Besides, bacterial and fungi growth showed a correlation with TPH (r = 0.86, p < 0.001; r = 0.77, p < 0.0034, respectively). It could be said that the agro-industrial by-products and macronutrients contributed to pollutant removal from the oil-polluted soil at relatively short amount of time. In addition, the enzymatic activities were increased after the treatment; in this study, the high sensitivity enzyme was AlP, and it could be used as an indirect indicator of oil pollutant removal.

The potential of agricultural waste materials for the removal bisphenol A (BPA) from aqueous solution was investigated. BPA is an endocrine-disrupting compound (EDC) used mainly in the plastic manufacturing industry. It may be hazardous to humans and animals because of its estrogenic activity. Agricultural wastes are sustainable adsorbents because of their low cost and availability. Hence, this study investigated the removal of BPA from water by adsorption onto treated coir pith, coconut shell and durian peel. The adsorption of BPA from water onto adsorbent was evaluated using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The effects of morphology, functional groups, and surface area on adsorption before and after pretreatment with sulfuric acid and reaction were investigated, and it was found that the treated adsorbent were able to remove BPA. Carbonyl and hydroxyl groups had appear in large number in FTIR analysis. The present study indicates that coir pith had removed 72 % of BPA with adsorption capacity of 4.308 mg/g for 24 h, followed by durian peel (70 %, 4.178 mg/g) and coconut shell (69 %, 4.159 mg/g). The results proved that these modified phyto-waste were promising materials as alternative adsorbent for the removal of BPA from aqueous solution.

Due to India’s population expansion, water recycling is critical to reducing water scarcity. The purpose of this study is to discuss the recycling and reuse of domestic greywater. The horizontal subsurface flow constructed wetland (HSSF-CW) was employed to treat greywater, with bioenergy crops replacing decorative plants. CO 86032 and CO 15027 sugarcane varieties were employed for phytoremediation. In a laboratory-scale HSSF-CW system with dimensions of 0.92 m, 0.61 m, and 0.45 m, coarse aggregate (20 mm), brick jelly (20 mm), and red soil mixed with coir pith (1/3 of coir pith volume-based) were employed as filter materials. During a hydraulic retention time (HRT) of 2 to 48 h, the maximum removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and total nitrogen (TN) was 77.78–90%, 69.92–81.20%, 82–91.06%, and 75.83–84.02%, respectively.

This work aims to enhance the energy cost-saving potential of conventional mud-brick by including natural waste materials as insulators. The solid waste materials considered for mud bricks are rice husk, sawdust, coir pith, and fly ash. This work investigates the structural and thermoeconomic performance of four types of insulated mud bricks and three roofs of ferrocement, clay, and ceramic materials. The thermal properties of walls and roofs were measured as per ASTM D 5334 standards. The utilization of solid waste in mud bricks enhanced the structural properties and air-conditioning cost-saving potential of the mud bricks. The results also showed the mitigation of greenhouse gas emissions with the usage of insulated bricks for buildings. The rice husk mud-brick wall showed better results of higher time lag, lower decrement factor, higher air-conditioning cost-savings, acceptable payback periods, and higher annual carbon mitigation values of 11.11 h, 0.24, 1.74 $/m², 1.17 years, and 33.35 kg/kWh, respectively, among all the studied multilayer walls. Among the roofs, clay tile roof showed a lower decrement factor (0.989), higher time lag (0.73 h), higher air-conditioning cost-savings (2.58 $/m²), lower payback periods (0.61 years), and higher annual carbon mitigation (21.73 kg/kWh). The results are in designing eco-friendly and energy-efficient envelopes for buildings.

Arsenic contamination in drinking water is a matter of concern for many countries. An efficient and low-cost solution for this hazard is essentially needed on urgent basis. Therefore, in this study, banana pith (an agricultural waste) was used for biochar production and later it was modified with iron and applied for arsenic adsorption from aqueous solution. Produced biochar was characterized for proximate, ultimate, and surface analyses. Interestingly, after iron impregnation, the surface area of biochar increased (31.59 m²/g) by nearly 8 times. Morphological analysis showed that iron particles firmly held within the pores after impregnation. Arsenate (As(V)) adsorption behavior of iron-impregnated banana pith biochar was evaluated through a batch study by considering various parameters like dose, concentration, pH, temperature, and competing anions. Compared to impregnated biochar, raw biomass and its biochar showed a lesser affinity for arsenate in aqueous solution. The adsorption isotherm of As(V) on banana pith biochar was covered in the temperature range of 298 to 318 K, and kinetic data of adsorption was experimentally generated at 298 K. Langmuir model for the sorption isotherms and pseudo-second-order kinetic model for the sorption kinetics represented the experimental data. The thermodynamic study showed negative Gibb’s free energy (− 46.88 kJ/mol at 298 K, − 48.58 kJ/mol at 308 K, − 50.73 kJ/mol at 318 K) that suggested spontaneity of the adsorption process. Negative enthalpy (ΔH° = − 10.55 kJ/mol) showed exothermic nature of adsorption of arsenic, while negative entropy (ΔS° = 0.123 kJ/mol.K) suggested enthalpy-driven adsorption process. Mechanism of arsenic adsorption onto iron-impregnated banana pith biochar has also been discussed in detail. Based on the experimental observation, a predictive model for arsenate removal has been developed in this study. The findings of the present study elucidated that iron-impregnated banana pith biochar can be used as a low-cost adsorbing material for As(V) from aqueous solutions.