Increasing environmental awareness coupled with more stringent regulation standards has triggered various industries to challenge themselves in seeking appropriate wastewater treatment technologies. Coagulation–flocculation process is regarded as one of the most important and widely used treatment processes of industrial wastewaters due to its simplicity and effectiveness. This paper provides a critical review on recent studies of coagulation–flocculation treatment processes of various industrial wastewaters. The limitations and challenges for the coagulation–flocculation process such as the toxicity and health hazard posed by inorganic coagulants, production of large amount of toxic sludge, ineffectiveness in removing heavy metals and emerging contaminants, increase in effluent color, inefficient pollutant removal using natural coagulants, and complexity of scaling up procedure are presented. In addition, an overview on the influence of process parameters on treatment efficiency is included in this revie...

Recent Advancement of Coagulation–Flocculation and Its Application in Wastewater Treatment

Cultivation of filamentous cyanobacteria (blue-green algae) in agro-industrial wastes and wastewaters: A review

A two-step acid-catalyzed process for the production of biodiesel from rice bran oil.

Reactor technologies for biodiesel production and processing: a review.

Production and comparative fuel properties of biodiesel from non-edible oils: Jatropha curcas, Sterculia foetida and Ceiba pentandra

Wastewater treatment in dairy industries — possibility of reuse

Sterculia foetida oil contains cyclopropene fatty acids namely 8,9-methylene-heptadec-8-enoic acid (malvalic) and 9,10-methylene-octadec-9-enoic acid (sterculic) to an extent of 50–55%. The present study reports the preparation of biodiesel from S. foetida oil using sodium hydroxide as catalyst. The resultant biodiesel was evaluated for physico-chemical properties namely iodine value (72.6), free fatty acids (0.17%), phosphorous content (0 ppm), flash point (179 °C), cloud point (3 °C), pour point (3 °C), viscosity at 40 °C (4.72 cSt), oxidative stability at 110 °C (3.42 h), density (0.850 g/cm3 at 15 °C), and trace metals (Group I metals 0.21 ppm). The properties were compared with that of sunflower, soybean and rapeseed oil-based biodiesels and found to be comparable except for the pour point.

Preparation and Evaluation of Biodiesel from Sterculia foetida Seed Oil

Rice bran oil, not being a seed-derived oil, has a composition qualitatively different from common vegetable oils and the conventional vegetable oil processing technologies are not adaptable without incurring huge losses. The oil's unusual high content of waxes, free fatty acids, unsaponifiable constituents, phospholipids, glycolipids and its dark color, all cause difficulties in the refining process. An attempt was made in this investigation to look into factors that are responsible for such difficulties and to develop suitable methodologies for physical refining of rice bran oil. Special attention was given to dewaxing, degumming and deacidification steps. The high content of glycolipids (∼6%) present in the oil was found to be a central problem and their removal appeared crucial for successful processing of the oil. We have also isolated and identified, for the first time, phosphorus-containing glycolipids that are unique to this oil. These compounds prevent a successful degumming of the oil and their high surface activity leads to unusually high refining losses during alkali refining. A number of simple processes has been evolved, including 1) a simultaneous dewaxing and degumming process, 2) an unusual enzymatic process to degum the oil, 3) processes for the removal of the glycolipids including the phosphoglycolipids and 4) a process for the isolation of the glycolipids which may have potential applications in the food, cosmetic and pharmaceutical industries. The processing protocol suggested here becomes the first and only one to produce an oil with less than 5 ppm of phosphorus from crude rice bran oil, rendering it thus suitable for physical refining. We believe that the present results are very significant and should contribute to a better utilization of this valuable oil. Cette etude examine les facteurs responsables des difficultes rencontrees lors de la production de l'huile de son de riz et tente de developper des procedures adaptees pour un raffinage physique de l'huile. L'attention est portee sur les etapes de deparaffinage, de demucilagination et de desacidification. La forte en teneur en glycolipides, notamment des glycolipides contenant du phosphore, consistue le probleme central et leur elimination est cruciale pour la reussite du procede.

Origin of problems encountered in rice bran oil processing

Jatropha curcus L. oil has emerged as one of the most important raw materials for biodiesel production. However, no detailed study has been reported on characterizing the lipid constituents of jatropha oil. The present study revealed that the total oil content of jatropha seeds was 32% with a composition of 97.6% neutral lipids, 0.95% glycolipids and 1.45% phospholipids. The fatty acid composition of total lipids, neutral lipids, phospholipids and glycolipids was also determined and found to contain oleic acid (18:1) and linoleic acids (18:2) as major fatty acids. The phospholipids fraction was further characterized and quantified and found to contain phosphatidyl choline (PC) 60.5%, phosphatidyl inositol (PI) 24% and phosphatidyl ethanolamine (PE) 15.5%. The fatty acid composition and the positional distribution of the fatty acids of individual phospholipids were also reported.

Phospholipid Composition of Jatropha curcus Seed Lipids

Rice bran oil (RBO) is not a seed-derived oil. Therefore, the crude oil obtained by conventional solvent extraction using hexane has a number of impurities that are required to be removed before human consumption. Unlike other oils, the bran contains a lipase enzyme that converts the neutral oil to free fatty acids (FFAs) and partial glycerides. The bran has to be either stabilized or it has to be subjected to solvent extraction immediately after rice milling. However, the crude RBO will have higher FFA contents compared to other common vegetable oils. The use of alkali for neutralization may result in higher refining loss. More importantly, RBO contains a number of minor constituents such as oryzanol, tocopherols, tocotrienols, squalene, phytosterols, steryl esters, etc. having proven health benefits. The major challenge for a processor is to keep most of these micronutrients intact in the refined oil. The addition of alkali reduces the micronutrient contents in refined oil. It is, therefore, evident that physical refining would be the preferred refining methodology for RBO. The major prerequisite for processing the oil through physical refining is to have phosphorus content

Pradosh Prasad Chakrabarti

Papers

Wastewater treatment in dairy industries — possibility of reuse

Preparation and Evaluation of Biodiesel from Sterculia foetida Seed Oil

Origin of problems encountered in rice bran oil processing

Phospholipid Composition of Jatropha curcus Seed Lipids

Processing Technology of Rice Bran Oil