Phycoremediation of industrial wastewater using Vaucheria debaryana and Cladophora glomerata

Indigenous bacteria as potential agents for trace metal remediation in industrial wastewater

Water pollution is a burning issue that can originate from both urbanization and industrialization. This study aimed to evaluate the industrial wastewater collected from Hayatabad Industrial Estate and to use indigenous bacteria, Pseudomonas aeruginosa and Enterobacter aerogenes for bioremediation. The water samples collected were analyzed for physicochemical parameters and microbial pollution. To analyze the pollution removal efficiency by indigenous bacterial species, a pot experiment was performed for 14 days. Before and after experiment, the water samples were analyzed for trace metal concentration by Atomic Absorption Spectroscopy. The biochemical and molecular analysis confirmed the presence of two bacterial species (P. aeruginosa and E. aerogenes). The industrial wastewater treated with these isolated bacterial species showed significantly decreased level of electrical conductivity (42.33-86.45%), dissolved oxygen (16.35-63.37%), biological oxygen demand (33.33-80.62%), chemical oxygen demand (00-83.52%), total suspended solids (00-80%), and total dissolved solids (0.00-54.93%). The P. aeruginosa removal efficiency for Cu, Cd, and Pb was ranging 77.58-82.35%, 19.67-50%, and 20.40-91.66%, respectively. Similarly, the E. aerogenes removed Cu, Cd, and Pb in the range of 47.05-60.61%, 54.55-62.29%, and 85.21-91.6%, respectively. Phytotoxicity results revealed that the wastewater treated with both P. aeruginosa and E. aerogenes gives better Triticum sp. % germination rate, leaf length, and root and shoot weight. The highest plant % germination was showed by treated P. aeruginosa in control (100%), followed by E. aerogenes in control (100%). The t- test analysis showed the concentration of trace metals (TM) in industrial wastewater was significantly reduced (p ≤ 0.05) by bacterio-remediation. The study concluded that both bacterial species are active in the removal of pollution and TM from the wastewater.

Methods Using Marine Aquatic Photoautotrophs along the Qatari Coastline to Remediate Oil and Gas Industrial Water

Qatar and other Gulf States have a diverse range of marine vegetation that is adapted to the stressful environmental conditions of seawater. The industrial wastewater produced by oil and gas activities adds further detrimental conditions for marine aquatic photosynthetic organisms on the Qatari coastlines. Thus, these organisms experience severe stress from both seawater and industrial wastewater. This review discusses the biodiversity in seawater around Qatar, as well as remediation methods and metabolic pathways to reduce the negative impacts of heavy metals and petroleum hydrocarbons produced during these activities. The role of microorganisms that are adjacent to or associated with these aquatic marine organisms is discussed. Exudates that are released by plant roots enhance the role of microorganisms to degrade organic pollutants and immobilize heavy metals. Seaweeds may have other roles such as biosorption and nutrient uptake of extra essential elements to avoid or reduce eutrophication in marine environments. Special attention is paid to mangrove forests and their roles in remediating shores polluted by industrial wastewater. Seagrasses (Halodule uninervis, Halophila ovalis, and Thalassia hemprichii) can be used as promising candidates for phytoremediation or bioindicators for pollution status. Some genera among seaweeds that have proven efficient in accumulating the most common heavy metals found in gas activities and biodegradation of petroleum hydrocarbons are discussed.

Toxicity, physiological response, and biosorption mechanism of Dunaliella salina to copper, lead, and cadmium

Background

Heavy metal pollution has become a global problem, which urgently needed to be solved owing to its severe threat to water ecosystems and human health. Thus, the exploration and development of a simple, cost-effective and environmental-friendly technique to remove metal elements from contaminated water is of great importance. Algae are a kind of photosynthetic autotroph and exhibit excellent bioadsorption capacities, making them suitable for wastewater treatment.

Methods

The effects of heavy metals (copper, lead and cadmium) on the growth, biomolecules accumulation, metabolic responses and antioxidant response of Dunaliella salina were investigated. Moreover, the Box-Behnken design (BBD) in response surface methodology (RSM) was used to optimize the biosorption capacity, and FT-IR was performed to explore the biosorption mechanism of D. salina on multiple heavy metals.

Results

The growth of D. salina cells was significantly inhibited and the contents of intracellular photosynthetic pigments, polysaccharides and proteins were obviously reduced under different concentrations of Cu2+, Pb2+ and Cd2+, and the EC50 values were 18.14 mg/L, 160.37 mg/L and 3.32 mg/L at 72 h, respectively. Besides, the activities of antioxidant enzyme SOD and CAT in D. salina first increased, and then descended with increasing concentration of three metal ions, while MDA contents elevated continuously. Moreover, D. salina exhibited an excellent removal efficacy on three heavy metals. BBD assay revealed that the maximal removal rates for Cu2+, Pb2+, and Cd2+ were 88.9%, 87.2% and 72.9%, respectively under optimal adsorption conditions of pH 5-6, temperature 20-30°C, and adsorption time 6 h. Both surface biosorption and intracellular bioaccumulation mechanisms are involved in metal ions removal of D. salina. FT-IR spectrum exhibited the main functional groups including carboxyl (-COOH), hydroxyl (-OH), amino (-NH2), phosphate (-P=O) and sulfate (-S=O) are closely associated with the biosorption or removal of heavy metalsions.

Discussion

Attributing to the brilliant biosorption capacity, Dunaliella salina may be developed to be an excellent adsorbent for heavy metals.