Microalgae and wastewater treatment

Organic and inorganic substances released into the environment as a result of domestic, agricultural and industrial activities often lead to serious pollution. A number of primary and secondary treatment processes are normally used to remove easily settled materials and biodegradable components of the wastewater. The final result is a clear, apparently clean effluent which is discharged into natural water bodies. This secondary effluent is, loaded with inorganic compounds and causes eutrophication and long-term problems because of refractory organics and heavy metals that are being discharged. The aim of this review paper is to determine in some detail the wastewater treatment using algae plant energy. However, algal production raises a number of sustainability concerns regarding land use, net energy return, water use, and nutrient supply. Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary treatment coupled with the production of potentially valuable biomass, which can be used for biofuels production. Microalgae cultures offer an elegant solution to tertiary treatments due to the ability of microalgae to use inorganic compounds for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, In the current review, the role of micro-algae in the treatment of wastewater and growth parameters to be affected for the cultivation. At the same time, algal cultivation has proven useful in waste treatment processes and thus this aspect is also treated in some detail.

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment

Chapter 7 - Application of microalgae in wastewater treatment: simultaneous nutrient removal and carbon dioxide bio-fixation for biofuel feedstock production

In the current article, we will highlight on the role of algae in the treatment of wastewater. Algae cultures are an interesting solution to tertiary and quandary treatments because of their capacity to use inorganic nitrogen and phosphorus for their growth and to remove heavy metals, as well as some toxic organic compounds, thus, avoiding a secondary pollution. Our experiments were conducted using Chlorella algae for removing lead ions from wastewater. The wastewater treatment efficiency reached a maximum of 86.67% after 80 minutes.

Due to its vast environmental benefits, green technology has succeeded in widespread usage in recent times. The treatment of wastewater through physico-chemical methods is always cost-intensive when employed in industries, especially in developing and underdeveloped countries. Consequently, researchers have drawn their attention in recent years to the importance of low-cost biological wastewater treatment with algae as an alternative to traditional wastewater treatment. Moreover, secondary effluents in wastewater treatment systems are filled with inorganic nitrogen and phosphorus and cause long-term problems due to persistent organics and discharged heavy metals. Microalgae cultures represent an important step in wastewater treatment as they provide solution to tertiary biotreatment coupled with producing biomass that can be used for different purposes. Also, microalgae have demonstrated their ability to biotransform and biodegrade a wide variety of contaminants, representing a promising biotechnological remediation method. The chapter has attempted to investigate the role of various algal species in reducing the pollution load from different wastewater effluents.

In Kenya, the devolved system of governance to counties is currently facing many challenges in the provision of basic services including wastewater management. Thus there is an attempt to explore the feasibility of using vegetative wastewater treatment systems that are economically viable and environmentally sustainable. The viable options available include: Constructed wetlands; use of micro-algae and the use of Moringa Oleifera , as an herbal coagulant. Constructed wetlands treatment systems are engineered systems that consist of two general categories namely: subsurface flow systems and free water surface systems. The subsurface flow systems have also been referred to as root zone systems; rock reed filters and vegetated submerged bed systems. Free water surface systems are frequently designed to maximize wetlands habitat values and reuse opportunities, while providing effective water quality improvement. Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Microalgae cultures offer an elegant solution to tertiary and quandary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, therefore, it does not lead to secondary pollution. The use of Moringa Oleifera , an herbal coagulant, which is free of constraints viz. pH and alkalinity, has been used to reduce wastewater pollution significantly in some studies. The results of the studies showed that an optimum dose of Moringa Oleifera (60 mg/L) was observed to reduce pollution parameters - initial BOD5 and COD of dairy wastewater to the tune of 55% and 60% respectively. This review highlights on the use of vegetative wastewater treatment systems like constructed wetlands, micro-algae and Moringa Oleifera in effluent management in counties of Kenya. Keywords: constructed wetlands, micro-algae, Moringa Oleifera, wastewater, faecal coliforms, coagulation

Phycoremediation offers an effective way for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Phycoremediation offers a favorable solution to tertiary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. Indeed, for their capacity to remove heavy metals, as well as some toxic organic compounds does not lead to secondary pollution. The present research was attempted to reduce the heavy metal pollutants from the mixture of artificial wastewater samples using cyanobacteria (blue-green algae). It expresses less harm to human, animal, and plant health, as well as damage to the world as parallel with the objective of Maqasid Syariah, to preserve and protect life (nafs). The research was conducted by developing two phases which were algae culturing and phycoremediation model system. Pseudanabaena and Synechococcus were cultivated in Bold’s Basal medium in optimum condition. Three mixture of different heavy metals (Pb, Fe, Cr, Cd, Al, and Cu) were tested. The treatments were run at three concentration of heavy metals, 1, 2, and 3 mg/L for 4 weeks in the treatment room, which every week the samples were analyzed by Inductively Coupled Plasma (ICP). The result of present investigation clearly indicated that Synechococcus was highly efficient for removal of Pb > Cr > Fe > Cu > Al > Cd respectively compared to Pseudanabaena. Amongst the selected algae, Synechococcus was a great candidate as good accumulator It was concluded that the cyanobacteria were the best alternative for phycoremediation.

Public health is seriously jeopardized in developing countries due to poor sanitation and the presence of persistent pollutants in natural water bodies. Open dumping, wastewater discharge without proper treatment and atmospheric fallout of the organic and inorganic pollutants are the main causes behind the poor condition. Some of the pollutants pose a greater risk due to their toxicity and persistence. Such a class of pollutants are known as chemical contaminants of emerging concern (CECC), including antibiotics and drug residues, endocrine disruptors, pesticides and micro- and nano-plastics. Conventional treatment methods cannot treat them properly and are often associated with several disadvantages. However, the chronological development of techniques and materials for their treatment has exhibited graphene as an efficient candidate for environmental remediation. This current review considers the various graphene-based materials, their properties, advancement in synthesis methods with time and their detailed application in removing dyes, antibiotics and heavy metals. It has been discussed how graphene and its derivatives exhibit unique electronic, mechanical, structural and thermal properties. In this paper, the mechanism of adsorption and degradation using these graphene-based materials has also been discussed vividly. In addition to this, a bibliographic analysis was performed to identify the trend of research related to graphene and its derivatives in the adsorption and degradation of pollutants round the globe reflected by the publications. Therefore, this review can be instrumental in understanding the fact that further development of graphene-based materials and their mass production can provide a very effective and economical wastewater treatment method.

The concentrations and removal of Cryptosporidium, Giardia, and microbial indicators, including somatic coliphages and fecal coliforms were investigated through the wastewater treatment processes at three municipal wastewater treatment plants in Beijing, China. The experimental results showed that the concentrations of Cryptosporidium in untreated wastewater, primary treatment effluent, secondary treatment effluent, tertiary treatment effluent were 33-600, 67-333, 0-9 and 0-0.4 oocysts L(-1), and that of Giardia were 130-3,600, 533-2,033, 0-32 and 0-2.1 cysts L(-1), respectively. The reduction ratios of Cryptosporidium and Giardia by the primary treatment process were 0.12 log and 0.18 log, respectively. Oxidation ditch process had higher reduction efficiency to Cryptosporidium and Giardia than anaerobic-anoxic-oxic process and conventional activated sludge process, probably because of longer retention time and higher sludge concentration. Membrane ultrafiltration had a notably better efficiency to reduce microorganisms, especially Cryptosporidium and Giardia, than conventional flocculation sedimentation and sand filtration process, as the tertiary treatment. Comparing with total coliforms, fecal coliforms and heterotrophic bacteria, concentration of somatic coliphages was correlated better with that of Cryptosporidium and Giardia in untreated wastewater and secondary treatment effluent.

The Egyptian water crisis has encouraged the exploration of innovative solutions for wastewater treatment. One promising approach is using treated agricultural drainage water for its large amount per year and low pollution. There are many methods used for the treatment of wastewater, but this research focused on a new one which is the use of microalgae for in-situ treatment of wastewater, due to its ability to uptake and adsorb pollutants, aerate water, and produce biomass for potential use as a biofuel or fertilizer. Microalgae have shown great potential for removing various pollutants from wastewater, including organic matter, nutrients, heavy metals, and pathogens. Moreover, the use of microalgae for wastewater treatment can be more cost-effective and sustainable than traditional wastewater treatment methods, which often require large and expensive infrastructure. This study aimed to investigate the effectiveness of using microalgae for in-situ treatment of agricultural drainage wastewater of Bahr El-Baqar drain. The results revealed that the removal efficiencies were 29% for BOD (biochemical oxygen demand), 46.9% for COD (chemical oxygen demand), 56.1% for TSS (total suspended solids), 31% for HM (Heavy Metal) removal, and 86% increment in DO (Dissolved Oxygen) concentration. This experiment provided evidence that microalgae could be a promising and cost-effective solution for in-situ treatment of agricultural drainage wastewater, with high removal efficiencies for pollutants in wastewater and the potential to reduce the need for constructing large and expensive wastewater treatment plants.

Chapter 13 - Process intensification of treatment of inorganic water pollutants

Golden alga (Prymnesium parvum) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga.

ISHS IV International Symposium on Ecologically Sound Fertilization Strategies for Field Vegetable Production EFFECT OF DISINFECTION SYSTEMS ON THE CONTENT OF INORGANIC AND ORGANIC CONTAMINANTS IN URBAN WASTEWATER

Textile industry wastewater has become a growing concern in recent years due to it has been characterized by a high load of organic dyes, suspended and dissolved solids, alkaline pH, and low biodegradability. As a result, environmental authorities necessitate textile industries to treat effluents before discharge into the environment. Tertiary filters, particularly membrane filtrations, are the most preferable process to recover good-quality water at the tertiary treatment phase, which feeds from secondary effluents, in wastewater treatment processes. However, fouling is still a challenge due to a higher load of suspended solids, colloids, organic matter, and a high level of bio-colloids (mostly from secondary effluents) in the textile wastewater treatment process. Bio-colloids are any colloidal entities of organic matter including microorganisms and their exudates. Hence, a coagulation/flocculation unit process, as a pretreatment option, is critical both at the primary treatment stage and after secondary (biological) effluents to prevent fouling problems at the tertiary filters. We reviewed identifying major foulants causing tertiary filter damage and the available pretreatment option for the removal of these foulants. We focus on and suggest the coagulation/flocculation process as a good pretreatment alternative to prevent filter fouling as it provides a reliable process to treat high water turbidity that arises from a high load of solids and colloids. Amongst different types of foulants, we focus on and present the colloidal solids and bio-colloidal foulants that could be major causes of fouling. These foulants are less understood and expected to be dominant in the textile industry wastewater, and established pretreatment alternatives are not well developed for the bio-foulants fed from the secondary effluent. Thus, these foulants need to be critically identified in the textile wastewater treatment plants to integrate suitable pretreatment options to prevent fouling potentiality. We proposed a coagulation/flocculation unit process as a pretreatment option to reduce colloidal and bio-colloidal fouling before the tertiary treatment stage, next to the secondary effluent, is critical.

Emergence of pollutants in wastewater, expensive cultivation of microalgae, and difficulties in industrial scale production are the main challenges for successful coupling of microalgae with wastewater. Nitrogen, carbon, and phosphorus in wastewater are deliberately consumed by microalgae and cyanobacteria for their growth and could act as green technology for wastewater treatment. In this review, the role and mechanistic approaches of microalgae and cyanobacteria for removal of various (in)organic compounds from wastewater have been thoroughly addressed. Distinct pathways have been reported for improving wastewater treatment technologies through large-scale cultivation of microalgal. The techno-economic feasibility and major commercial production challenges along with genetic engineering research have been addressed. A biorefinery approach with integrated biology, ecology, and engineering would lead to a feasible microalgal-based technology for various applications.