Comparative performance studies of water lettuce, duckweed, and algal-based stabilization ponds using low-strength sewage

Implementation of water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) in the re-treatment of conventionally treated pharmaceutical wastewater: a case study of Radiant Pharmaceuticals Limited, Dhaka, Bangladesh

Since Bangladesh already has robust pharmaceutical industries, nearly all companies owned effluent treatment plant (ETP) facilities to improve the quality of wastewater. Water retreatment utilizing affordable, accessible, and environmentally sustainable techniques have not yet been thoroughly investigated. In this study, the potential of water hyacinth and water lettuce was investigated at three different concentrations: 50% of total volume coverages (1000 g macrophytes/2000 ml water), 75% of total volume coverages (1500 g macrophytes/2000 ml water), and 100% of total volume coverages (2000 g macrophytes/2000 ml water) on the post-treated ETP's wastewater for 3 weeks in a mesocosm environment. Heavy metals, such as chromium (Cr) and nickel (Ni) along with physicochemical parameters (pH, EC, TDS, DO, and BOD5) were measured after 7 days intervals. Results indicated that water hyacinth was considerably more efficient than water lettuce at removing many factors, including metals. Water hyacinth was able to remove 79.15% of nickel and 92.97% of chromium while also increasing DO and EC by 36.72% and 14.59%, respectively, at 100% of total volume coverages. On the other hand, 100% of the total volume coverage of water lettuce decreased the pH, TDS, and BOD5 readings by 6.70%, 31.62%, and 87.61%, respectively. With each treatment, the water quality significantly improved over the control. The findings suggest that the pharmaceutical industries may improve the quality of their treated wastewater even more by integrating phytoremediation technology with traditional ETP facilities.

Performance assessment of local aquatic macrophytes for domestic wastewater treatment in Nigerian communities: A review

The concept of treating wastewater before disposal is a global necessity. Recent mechanisms of doing this include the use of Constructed Wetland Systems (CWS). This technique is believed to be cost-effective and simpler compared to conventional methods. The application of this system is primarily dependent on the use of plants through the phytoremediation process. There is evidence of the potential of some locally found Nigerian aquatic plants such as water lettuce, water hyacinth and duckweed to be applicable for this purpose. However, there is little information on their performance level in remediating domestic wastewater. Thus, this review paper assessed the performance of these local macrophytes for domestic wastewater treatment and the potential of contributing the same in Nigerian communities. This was done by reviewing recent literature on the role of water lettuce, water hyacinth and duckweed, their occurrence and their efficiency in minimising different wastewater contaminants. Contaminant indicators such as total solids, electrical conductivity (EC), BOD, COD, dissolved oxygen, total phosphorous, total nitrogen, and heavy metals have been reduced using these macrophytes. The review indicates that the selected macrophytes do not only have the potential for wastewater purification but high efficiencies in doing so when applied appropriately in the Nigerian communities.

Phytoremediation potentials of Eichhornia crassipes for nutrients and organic pollutants from textile wastewater

We used live water hyacinth (WH, Eichornnia crassipes) to purify effluents from textile factories and monitored changes in the physicochemical properties, organic pollutants, and WH biomass. Although the water plant could not thrive in the highly polluted effluents after eight weeks, it achieved 55, 91, 53, 84, 96, 53, and 55% removal efficiency for total Kjeldahl-N (tK-N), NH₃-N, organic-N, PO₄^3-, SO₄^2-, Cl^-, and hardness, respectively. Likewise, the biomass growth showed a positive and strong correlation with NH₃-N (0.998), tK-N (0.956), organic-N (0.923), pH (0.853), and EC (0.712). In contrast, chemical oxygen demand and total oil and grease (TOG) evinced negative and strong correlations of -0.994 and -0.807, respectively. Further, Cl^- correlated mildly (-0.38), while alkalinity (0.154) and water hardness (-0.296) were less influential on the biomass growth. From the removal models, an average of 312 ± 7.7 g of WH would ensure 100% remediation of the nutrients in 29.2 ± 2.5 days. Except for organic-N, the removal kinetics generally favors pseudo-first-order, suggesting the sorbates' concentration and contact time as the limiting factors. Conclusively, WH is a phytoremediator of high potentials for industrial textile effluents, provided the effluents are conditioned at optimum concentration before contact with mature WH of sufficient biomass weight. Novelty statement Eichhornia crassipes was used for simultaneous removal of nutrients and organics from textile effluents. The influence of the macrophte's biomass weight and maturity on the remediation process were examined. Also, the limiting parameters that govern the remediation process were investigated via statistical correlation and kinetic study.

Novel preparation of fungal conidiophores biomass as adsorbent for removal of phosphorus from aqueous solution

The present study focused on phosphorus adsorption by novel fungal conidiophores biomass in aqueous solution. Fungal Conidiophores biomass was prepared from the fungal strains Aspergillus oryzae (YFK) and Fusarium oxysporum (YVS2). The functional groups and morphology of Conidiophores Biomass (CB) from these strains were characterized by FTIR and SEM. FTIR confirms the presence of alcohol, carboxylic acid, carbon dioxide, cyclic alkene, amine, alkene, fluoro compound, and halo compound groups. Batch mode study was carried out with two CB's such as Aspergillus oryzae CB (ACB) and Fusarium oxysporum CB (FCB) with initial concentration of phosphorus ranging from 20 to 100 mg L^-1. Based on the batch experiments, the adsorption kinetics (pseudo first order and pseudo second order), isotherms (Freundlich and Langmuir models), and thermodynamic (standard entropy, energy, and enthalpy) parameters were calculated. The adsorption kinetics and isotherm studies showed that the adsorption data well fitted with PSO kinetic model. From the isotherm results, it was found that ACB and FCB exhibited highest adsorption capacity 25.64 mg g^-1 and 26.32 mg g^-1 of phosphorus respectively at the optimal condition of pH (7), time (90 min), dose (250 mg), and room temperature (35 °C). Thermodynamics values were found to be endothermic and spontaneous in nature for phosphorus adsorption. Finally, the results suggested that the ACB and FCB are economically feasible cost-effective adsorbent for removal of phosphorus in wastewater treatment. Graphical abstract.

Biochar-based constructed wetlands to treat reverse osmosis rejected concentrates in chronic kidney disease endemic areas in Sri Lanka

The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20-85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K⁺, Ca⁺², Mg⁺², etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters.

Phytoremediation of parboiled rice mill wastewater using water lettuce (Pistia stratiotes)

Phytoremediation is an emerging technology applied for treatment of wastewater. It is a suitable option notably in developing countries as it is simple, sustainable and cost effective. In the present lab-based batch study the free floating aquatic plant water lettuce (Pistia stratiotes) is used for treatment of parboiled rice mill wastewater having low pH, high chemical oxygen demand (COD), nitrogen, and phosphate. In raw rice mill wastewater (undiluted) growth of water lettuce is found to be inhibited. Later on, two different dilution approaches (raw and facultative pond effluent 1:1; raw and tap water 1:1) are applied in order to effectively use this technology. In all cases a control (without plant) is maintained to compare the performance with the Aquatic Plant based Treatment (APT) system. In the APT system results reveal that removal of soluble COD (SCOD), ammoniacal nitrogen (NH4-N), nitrate nitrogen (NO3-N), and soluble phosphorus (sol. P) are upto 65%, 98%, 70%, and 65% respectively. The study highlights the efficacy of water lettuce in removing organics and nutrients from parboiled rice mill wastewater.

Remediation of nutrient-rich waters using the terrestrial plant, Pandanus amaryllifolius Roxb

Effective control of eutrophication is generally established through the reduction of nutrient loading into waterways and water bodies. An economically viable and ecologically sustainable approach to nutrient pollution control could involve the integration of retention ponds, wetlands and greenways into water management systems. Plants not only play an invaluable role in the assimilation and removal of nutrients, but they also support fauna richness and can be aesthetically pleasing. Pandanus amaryllifolius, a tropical terrestrial plant, was found to establish well in hydrophytic conditions and was highly effective in remediating high nutrient levels in an aquatic environment showing 100% removal of NO3(-)-N up to 200 mg/L in 14 days. Phosphate uptake by the plant was less efficient with 64% of the PO4(-)-P removed at the maximum concentration of 100 mg/L at the end of 6 weeks. With its high NO3(-)-N and PO4(3-)-P removal efficiency, P. amaryllifolius depleted the nutrient-rich media and markedly contained the natural colonization of algae. The impediment of algal growth led to improvements in the water quality with significant decreases in turbidity, pH and electrical conductivity. In addition, the plants did not show stress symptoms when grown in high nutrient levels as shown by the changes in their biomass, total soluble proteins and chlorophyll accumulation as well as photochemical efficiency. Thus, P. amaryllifolius is a potential candidate for the mitigation of nutrient pollution in phytoremediation systems in the tropics as the plant requires low maintenance, is tolerant to the natural variability of weather conditions and fluctuating hydro-periods, and exhibit good nutrient removal capabilities.

The fate of isoproturon in a freshwater microcosm with Lemna minor as a model organism

Degradation, bioaccumulation and volatile loss of the 14C-labeled phenylurea herbicide isoproturon (IPU) was examined in a freshwater microcosm with the free floating macrophyte species Lemna minor during a 21-day exposure time. Isoproturon volatilisation was very low with 0.13+/-0.01% of the initially applied herbicide. Only a minor amount of the herbicide was completely metabolised, presumably by rhizosphere microorganisms and released as 14CO2. In total, about 9% isoproturon was removed from the aquatic medium during 21 days. The major portion of the pesticide was removed by bioaccumulation of Lemna minor (5.0+/-0.8%) and the bioconcentration factor (BCF) based on freshweight was 15.8+/-0.2. However, this study indicated a high persistence of IPU in freshwater ecosystems and a potential hazard due to bioaccumulation in non-target species. The novel experimental system of this study, developed for easy use and multiple sampling abilities, enabled quantitatively studying the fate of isoproturon and showed high reproducibility with a mean average (14)C-recovery rate of 97.1+/-0.7%.