Fenugreek mucilage for solid removal from tannery effluent

Guar gum, a low-cost sustainable biopolymer, for wastewater treatment: A review

Rapid population growth and the resultant pollution of freshwater resources have created a water stress condition reducing the availability of safe and affordable water. Guar gum, a biocompatible macromolecule obtained from the endosperm of the seeds of Cyamopsis tetragonolobus, is a fascinating raw material for multifunctional adsorbents. This review assembled the work conducted by various researchers over the past few decades and discussed the structure, properties, and different modifications methods employed to develop versatile guar gum-based adsorbent. The paper also summarized the recent progress of guar gum-based nanocomposites for the remediation of multiple hazardous substances such as organic dyes, toxic heavy metal ions, oil-water separation as well as inhibiting the growth of bacterial pathogens. Thus, the important contribution of guar gum composites to safeguard the water quality is highlighted which will overcome the limitations and streamline the future course of innovative research.

Assessment of the application of cladode cactus mucilage flocculants for hot chemical degreasing electroplating wastewater treatment and reuse: process efficiency and storage stability

Pressures related to urban growth and industrial activities exacerbated by climate change had an impact on water resources in Tunisia. The present study examines the application of cladode cactus mucilage (CCM) flocculants for hot alkaline chemical degreasing Zn-electroplating wastewater treatment and reuse (WWTR). The CCM flocculation process was selected through their environmental benefits, economic facilities, sustainable use of the natural biopolymer product, input biopolymers substitution, and on-site treated wastewater (TWW) reuse and recovery. The alum coagulation and CCM flocculation were performed by the jar test series. The suitability of treated wastewater quality (TWWQ) with alum/CCM was also assessed for reuse purpose in terms of corrosion-scaling indices (RSI, LSI, PSI, AI), oxidation-reduction potential (ORP), and microbiological community growth (Bacillus, Pseudomonas, Mesophilic bacteria and yeasts) for 28 days storage at 25 °C. The total alkalinity removal efficiency reached 95.8% with an optimum dosage of alum + CCM for hot alkaline chemical degreasing wastewater bath rinsing. The results showed that the stability of TWWQ has significantly deteriorated during storage leading to aggressive wastewater, pathogen growth, and biological malodor production which make them unsuitable for reuse. Therefore, there is a need for CCM processing alternatives that preserve the physico-chemical and microbial of TWW properties during storage.

Wastewater treatment using plant-derived bioflocculants: green chemistry approach for safe environment

The rapid expansion of global trade and human activities has resulted in a massive increase in wastewater pollution into the atmosphere. Suspended solids, organic and inorganic particles, dissolved solids, heavy metals, dyes, and other impurities contained in wastewater from various sources are toxic to the atmosphere and pose serious health risks to humans and animals. Coagulation-flocculation technology is commonly used in wastewater treatment to remove cell debris, colloids, and contaminants in a comfortable and effective manner. Flocculants, both organic and inorganic, have long been used in wastewater treatment. However, because of their low performance, non-biodegradability, and associated health risks, their use has been limited. The use of eco-friendly bioflocculants in wastewater treatment has become essential due to the health implications of chemical flocculants. Because of their availability, biodegradability, and protection, plant-derived coagulants/flocculants and plant-based grafted bioflocculants have recently made significant progress in wastewater treatment. This study will undoubtedly provide a clearer understanding of the current state, challenges, and solutions for bioflocculation in wastewater remediation using green materials for the sake of a cleaner climate.

Arabinoxylan and rhamnogalacturonan mucilage: Outgoing and potential trends of pharmaceutical, environmental, and medicinal merits

Demand for safe, environmentally friendly and minimally processed food additives with intrinsic technological (stabilizing, texturizing, structuring) and functional potential is already on the rise. There are actually several natural excipients eligible for pharmaceutical formulation. Mucilage, as a class constitutes arabinoxylan and rhamnogalacturonan-based biomolecules used in the pharmaceutical, environmental as well as phytoremediation industries owing to its particular structure and properties. These compounds are widely used in pharmaceutical, food and cosmetics, as well as, in agriculture, paper industries. This review emphasizes mucilage valuable applications in the pharmaceutical and industrial fields. In this context, much focus has recently been given to the valorization of mucilage as an ingredient for food or nutraceutical applications. Furthermore, different optimization and extraction techniques are presented to develop better utilization and/or enhanced yield of mucilage. The highlighted mucilage extraction methods warrant assessing up-scale processes to encourage for its industrial applications. The current article capitalizes on cutting-edge characteristics of mucilage and posing for other possible innovative applications in non-food industries. Here, the first holistic overview of mucilage with regards to its physicochemical properties and potential novel usages is presented.

Efficient bioremediation of tannery wastewater by monostrains and consortium of marine Chlorella sp. and Phormidium sp

This study evaluated the bioremediation potential of two marine microalgae Chlorella sp. and Phormidium sp., both individually and in consortium, to reduce various pollutants in tannery wastewater (TW). The microalgae were grown in hazardous 100% TW for 20 days, and the reductions in biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorous (TP), chromium (Cr) and total dissolved solids (TDS) of the wastewater monitored periodically. Both marine isolates reduced the BOD and COD by ≥90% in the consortium and by over 80% individually. Concentrations of TN and TP were reduced by 91.16% and 88%, respectively, by the consortium. Removal/biosorption efficiencies for chromium ranged from 90.17-94.45%. Notably, the TDS, the most difficult to deal with, were reduced by >50% within 20 days by the consortium. The novel consortium developed in this study reduced most of the ecologically harmful components in the TW to within the permissible limits of discharge in about 5 to 15 days of treatment. Thus, both the tested marine strains of Chlorella and Phormidium sp. are promising for bioremediating/detoxifying TW and adequately improve the water quality for safe discharge into open water bodies, in particular when used as a consortium.

Optimisation of extraction and sludge dewatering efficiencies of bio-flocculants extracted from Abelmoschus esculentus (okra)

The production of natural biopolymers as flocculants for water treatment is highly desirable due to their inherent low toxicity and low environmental footprint. In this study, bio-flocculants were extracted from Hibiscus/Abelmoschus esculentus (okra) by using a water extraction method, and the extract yield and its performance in sludge dewatering were evaluated. Single factor experimental design was employed to obtain the optimum conditions for extraction temperature (25-90 °C), time (0.25-5 h), solvent loading (0.5-5 w/w) and agitation speed (0-225 rpm). Results showed that extraction yield was affected non-linearly by all experimental variables, whilst the sludge dewatering ability was only influenced by the temperature of the extraction process. The optimum extraction conditions were obtained at 70 °C, 2 h, solvent loading of 2.5 w/w and agitation at 200 rpm. Under the optimal conditions, the extract yield was 2.38%, which is comparable to the extraction of other polysaccharides (0.69-3.66%). The bio-flocculants displayed >98% removal of suspended solids and 68% water recovery during sludge dewatering, and were shown to be comparable with commercial polyacrylamide flocculants. This work shows that bio-flocculants could offer a feasible alternative to synthetic flocculants for water treatment and sludge dewatering applications, and can be extracted using only water as a solvent, minimising the environmental footprint of the extraction process.

Natural Polysaccharides as Treatment Agents for Wastewater

This chapter gives an account of recent developments in biopolymers with an emphasis on natural polysaccharides as treatment agents in wastewater remediation. Almost all sources of water around the world are polluted to some degree, owing to a heavy influx of industrial effluents, domestic and agricultural wastes. These discharges vary from simple nutrients to highly toxic hazardous chemicals. Numerous approaches have been studied for the development of cheaper and more effective water remediation agents containing natural polymers. Among these, natural polysaccharides deserve particular attention. These materials have proved to be better treatment alternatives compared to their synthetic counterparts because of their particular structure, physicochemical characteristics, chemical stability, high reactivity and excellent selectivity towards aromatic compounds, metals and other contaminants that cause water pollution.

Biotreatment of industrial tannery wastewater using Botryosphaeria rhodina

The treatment of a tannery wastewater was performed on the laboratory scale using the ascomyceteous fungus Botryosphaeria rhodina MAMB-05, a ligninolytic and a constitutive producer of laccases (EC: 1.10.3.2). The wastewater samples were collected in the retanning and dyeing steps and presented high values of chemical oxygen demand, COD, (15,023 ? 60.0 mg L-1), fifth-day biochemical oxygen demand, BOD5, (4,374 ? 0.1 mg L-1), total solids (28,500 ? 2.0 mg L-1), total organic carbon, TOC, (4,685 mg L-1), and chloride ion concentration (2,911 ? 0.3 mg L-1). The fungus was inoculated and after five days under agitation at 180 rpm at 28?C, the COD was reduced by 91%. The total organic carbon also decreased from 4,685 to 375.0 mg L-1 and the turbidity from 331.0 to 6.5 NTU, indicating that the biological treatment was efficient as the fungus consumed almost all the organic compounds present in the wastewater. It was not necessary to add an additional carbon source for the treatment, indicating that the concentration of organic compounds presented in the tannery wastewater effluent were sufficient for microorganism growth, during which the COD and TOC were reduced by about 91 and 93%, respectively.

Molecular spectroscopic study of acid treated fenugreek seeds

Fenugreek seeds were subjected to acid treatment in order to activate its surface. XRF indicated that there was no change in the level of metals and metal oxides as a result of the treatment. FTIR of the treated fenugreek showed no change in the characteristic bands and/or structure of the fenugreek. A shift in both OH and metal oxide bands suggest a role for metal, hydrated metal and metal oxide in fenugreek seed. Molecular modeling suggests that metal oxides such as Al16O24 offer its surface for the adsorption of gases. The interaction of gases with metal oxide is depending on the type of gas rather than the type of coordination. Finally results indicate that fenugreek could be used safely to control the level of gases in stomach.

Batch adsorption and kinetics of chromium (VI) removal from aqueous solutions by Ocimum americanum L. seed pods

In this paper batch removal of hexavalent chromium from aqueous solutions by Ocimum americanum L. seed pods was investigated. The optimum pH and shaker speed were found to be 1.5 and 121 rpm. The equilibrium adsorption data fit well with Langmuir isotherm. The maximum chromium adsorption capacity determined from Langmuir isotherm was 83.33 mg/g dry weight of seed pods at pH 1.5 and shaker speed 121 rpm. The batch experiments were conducted to study the adsorption kinetics of chromium removal for the concentrations of 100 mg/L, 150 mg/L and 200mg/L chromium solutions. The adsorbent dosage was 8 g dry seed pods/L. The removal efficiency observed for all the three chromium concentrations was 100%. The equilibrium was achieved less than 120 min for all the three concentrations. The adsorption kinetic data was fitted with first and second order kinetic models. Finally it was concluded that the chromium adsorption kinetics of O. americanum L. seed pods was well explained by second order kinetic model rather than first order model.

Anaerobic digestion of tannery soak liquor with an aerobic post-treatment

The leather industry occupies a place of prominence in the Indian economy due to its massive potential for employment, growth and exports. The potential environmental impact of tanning is significant. This study focuses on tannery soak liquor, generated by the soaking of hides and skins, which is characterised by high organic load and high salinity. For these reasons, the soak liquor should be segregated and pre-treated separately before being mixed with the composite wastewater, made of all other streams mixed together. The anaerobic digestion of tannery soak liquor was studied using a UASB. COD removal reached 78% at an OLR of 0.5 kg COD m(-3) d(-1), a HRT of 5 days and a TDS concentration of 71 gl(-1). The combination of the UASB with an aerobic post-treatment enhanced the performance of the overall wastewater treatment process and the COD removal efficiency of the combined anaerobic/aerobic treatment system reached 96%. However, for effective operation, the system had to be operated at very low OLRs, which affects the economic viability of such a process.