Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Advanced oxidation of landfill leachate: Removal of micropollutants and identification of by-products.

In this study, Z-scheme MoSSe quantum dots (QDs) are synthesized by a facile hydrothermal process for photodegradation of tetracycline (TC) with visible light activity. Compared to original bulk Mo...

Direct Z-Scheme Heterostructures Based on MoSSe Quantum Dots for Visible Light-Driven Photocatalytic Tetracycline Degradation

The wastewater originates from different industrial, municipal, and agriculture processes and contains different nitrogen sources, for example, nitrate, ammonium, nitrite, and phosphate such as inorganic and organic sources. The discharge of high nitrate and phosphate to the ecosystem or nearby water bodies can cause eutrophication which disbalances the aquatic ecosystem. Furthermore, ingestion of these pollutants can cause severe toxicity and disease to humans and animals. Thus, from an environmental and social perspective, its treatment is essential with no negative impact on the ecosystem. Microalgae are fundamental, mixotrophic microorganisms that treat different wastewater and utilize nitrate and phosphate in the medium as a source of nutrients. Among them, Picochlorum sp., have the potential to remove nitrogen and phosphate from wastewater. The biomass produced by Picochlorum sp. can be a promising candidate as a sustainable feedstock for biofuel and bioproducts formation. Thus, the present review provides a brief knowledge and understanding about the concentration of nitrogen and phosphate in different wastewater, their negative impacts, and the uptake mechanism of microalgae. Furthermore, the review also provides an insight into Picochlorum sp., and the effects of different physiological and nutritional factors on their growth, wastewater treatment efficacy, and biomass for value-added products and biorefinery applications. In addition, the review is useful to understand the potential of Picochlorum sp. for a tenable wastewater treatment process.

Phycoremediation of nitrogen and phosphate from wastewater using Picochlorum sp.: A tenable approach.

Microalgae Chlorella vulgaris and Scenedesmus dimorphus co-cultivation with landfill leachate for pollutant removal and lipid production.

A feasibility study on optimization of combined advanced oxidation processes for municipal solid waste leachate treatment

Sustainable resources management, incorporating energy markets and resources such as electricity, fossil fuels, renewable and sustainable energy capital is essential for society to understand production and conversion of various forms of energy, their current as well as future supply. Waste-to-energy (WTE) or energy-from-waste (EFW) is a well-identified transitional technology which could prevent complete depletion of renewable resources. In our present study, the selected microalgae (Chlorella pyrenoidosa) was cultured in paddy-soaked wastewater (PWW) using outdoor raceway ponds of 50 L capacity where biotransformation of nutrients (NH3–N removal: 75.89 ± 0.69%; PO4–P removal: 73.71 ± 0.75%; yield co-efficient YN: 6.12 mg biomass/mg of N; YP: 7.77 mg biomass/mg P) has occurred with better growth and biochemical composition (dry biomass weight: 1.56 ± 0.11 g/L; chlorophyll: 15.57 ± 0.14 mg/L; specific growth rate (SGR): 0.42/d; lipids: 27.47 ± 1.41% biomass; carbohydrates: 23.77 ± 1.00% and protein: 46.12 ± 3.55%). Further, the obtained algal lipid was identified for a wide range of fatty acid methyl esters (FAME) and consequently brought forward to in-situ single-step transesterification by optimizing reaction conditions. Central composite design (CCD) of response surface methodology (RSM) has given optimized conditions of sample amount: 2 g (wet); methanol sulphuric acid volume: 3 mL; and hexane volume: 4 mL, under the reaction temperature of 90 °C for maximum biodiesel conversion (46.54% of algal lipids). The outcome of our current research may add value to the application and development of WTE technology for sustainable energy conservation.

Outdoor cultivation of Chlorella pyrenoidosa in paddy-soaked wastewater and a feasibility study on biodiesel production from wet algal biomass through in-situ transesterification

This book chapter presents a review on the application and challenges of microalgae (phycoremediation) for wastewater treatment. Primarily, the general brief is an investigative focus that compares current technologies in wastewater research around the globe and emphasizes the positive aspects of the phycoremediation approach. Much scientific literature has reported the feasibility and innovative merits of phycoremediation, particularly on the assimilation and accumulation of nutrients from wastewater. We discuss the potential of the technology, based on existing reports such as the advantages and disadvantages of phycoremediation. Subsequently, the biomass application from certain quantities of wastewater will have a benefit in the form of commercial applications. The chapter ends with a discussion of trends and future directions based on the detailed literature review with a focus on ensuring safer and sustainable implementation of phycoremediation.

J. Umamaheswari

Papers

A feasibility study on optimization of combined advanced oxidation processes for municipal solid waste leachate treatment

Outdoor cultivation of Chlorella pyrenoidosa in paddy-soaked wastewater and a feasibility study on biodiesel production from wet algal biomass through in-situ transesterification

Phycoremediation: An Integrated and Eco-friendly Approach for Wastewater Treatment and Value-Added Product Potential