Global J. Environ. Sci. Manage. 6(4): 553-578, Autumn 2020 Global Journal of Environmental Science and Management (GJESM) Homepage: https://www.gjesm.net/ REVIEW PAPER Use of natural coagulants for industrial wastewater treatment S. Gautam and G. Saini* Department of Civil Engineering, School of Engineering and Technology, Sharda University, Uttar Pradesh, India ARTICLE INFO ABSTRACT Industrial effluents are a menace to the environment and the fact that their Article History: Received 02 February 2020 characteristics vary from industry-to-industry only adds to the complex challenge Revised 15 April 2020 they offer to the engineers and scientists. Resource-efficient and environment- Accepted 18 May 2020 friendly solutions to this hazard are a call of the hour. Coagulation, by synthetic chemicals, has been used as a cost-effective and efficient method for managing Keywords: the effluents generated by a large number of industries. However, the synthetic Coagulation chemicals themselves are a cause of concern due to their non-native nature, Chemical coagulant non-degradability, and health conditions associated with their left-over Environment-friendly residues. Natural coagulants offer a cost-effective, environment-friendly, and Industrial Wastewater sustainable alternative to the application of synthetic chemicals. Such natural Natural coagulant coagulants, despite their demonstrated effectiveness in treating the industrial wastewaters, have their own limitations and are yet to be investigated for large-scale applications. The current work presents a state-of-the-art review of the natural coagulants’ application in treating industrial wastewaters and their relative advantages and disadvantages as compared to the chemical coagulants. Future research areas have also been identified that may ultimately lead to the large-scale commercial application of natural coagulants and will result in an environment-friendly and sustainable solution to the problems created by industrial effluents and synthetic chemical coagulants. DOI: 10.22034/gjesm.2020.04.10 ©2020 GJESM. All rights reserved. NUMBER OF REFERENCES NUMBER OF FIGURES NUMBER OF TABLES 190 0 3 *Corresponding Author: Email: [email protected] Phone: +91 828 705 1260 Fax: +91 828 705 1260 Note: Discussion period for this manuscript open until January 1, 2021 on GJESM website at the “Show Article. S. Gautam and G. Saini INTRODUCTION wastewater contains heavy metals which are a Rapid industrialization has posed many threats to potential cause of concern for the environment and et al the environment due to the wastewater generation human health (Ahemd ., 2020). Prasad and Rao through various industrial processes. Indiscriminate 2016 studied the impact of the cadmium pollution, disposal of this wastewater (with or without an caused due to the discharges from the mining appropriate level of treatment) can cause water activities. Elevated levels of cadmium can cause pollution and land pollution. This has a profound diseases like Itai-Itai; whereas, at low levels, it may effect on the health of living beings apart from the cause problems like kidney damage, sterility among impacts on the abiotic components such as soil males, flu disorders, and high blood pressure. The (Chhonkar et al., 2000) and water (Pal et al., 2010). characteristics of wastewater have been studied in Some key sources of industrial wastewater are palm terms of key parameters like BOD (Sehar et al., 2013), oil mills (Bhatia et al., 2007; Jagaba et al., 2020), TDS, COD (Rathi and Puranik, 2002), and color. These paper and pulp industry (Ashrafiet al., 2015; Wang et parameters help in gauging the level of potential al., 2011; Chaudhari et al., 2010), brewery and winery hazard the effluent can pose to the environment and (Brito et al., 2004), cosmetic industry (Naumczyk et human health. Due to the potential toxicity, industrial al., 2014), tannery industry (Rameshraja and Suresh, effluents may require prior treatment before their 2011), slaughterhouses (Bustillo-Lecompte et al., release into the environment. Improper disposal of 2015), paint industry (Aboulhassan et al., 2014), dairy the wastewater can cost liability in addition to their industry (Triques et al., 2020), etc. A huge quantity environmental impacts (Elsheikh and Al-Hemaidi, of industrial wastewater is generated worldwide 2013). Sahu and Chaudhari 2013 suggested that daily. Saha et al. (2005) claimed that a single unit industrial wastewater management is necessary to of Indian distillery uses 1133.5 KLD of water, and, eliminate the health and socio-economic concerns. after processing, around 668 KLD of wastewater Wastewater treatment technologies can be physical, is generated. In another attempt to quantify the chemical, or biological (Elsheikh and Al-Hemaidi, wastewater generation in India, Majumder et al. 2013). Among the physicochemical processes, (2014) estimated that every day around 13,468 MLD coagulation-flocculation has been frequently of wastewater is generated, out of which, more than used. In this process, the charge of the colloidal 50% is discharged into the environment untreated. particles is destabilized with the help of coagulants The quantity and quality of industrial effluent are (typically aluminium or iron salts) which results functions of the ongoing industrial process, raw in floc formation due to collision of destabilized material utilized, and products manufactured in each particles and their aggregation, which ultimately industrial unit, and therefore the composition and gets separated from the liquid phase. An alternative constitution of wastewater generated are different to the conventional coagulation-flocculation is the for different industries. For instance, the textile electrocoagulation process. Here, coagulants are dyeing processes in the textile industry generate formed due to electro-dissolution of the anode colored wastewater rich in chemical dyes (Ariffin which causes hydrolysis products that result in the et al., 2009). On the other hand, the effluent from destabilization of the particles (Verma and Kumar, paper and pulp industry contains large quantities of 2018). Electrocoagulation has been successfully sodium salts of organic acids, lignin, etc. (Wang et al., used for the treatment of textile wastewater using 2011). Wastewater from the cosmetic industry has iron and aluminium electrodes (Kobya et al., 2003), significant concentrations of COD, oils, detergents, synthetic textile wastewater (Merzouk et al., 2011), fats, and suspended solids (Tobajas et al., 2014). sewage (Carballa et al., 2005), vegetable oil refinery Muralimohan et al. (2014) studied the various wastewater (Tezcan et al., 2009), paint industry processes contributing to the wastewater generation wastewater (Akyol, 2012), olive oil mill wastewater in the textile industry. The study revealed that (Salameh, 2015), petroleum refinery wastewater (El- processes like cleaning, de-sizing, etc. are responsible Naas et al., 2009), etc. This process has also been for toxic wastewater generation. The main high-risk used to successfully remove harmful substances, constituents of this wastewater are chemicals, dyes, such as Diclofenac (responsible for vulture population bleaching agents, oils, acids, bases, etc. Sometimes, decline) (Oaks et al., 2004; Green et al., 2004), and 554 Global J. Environ. Sci. Manage., 6(4): 553-578, Autumn 2020 a carcinogenic dye, acid red 14 (Ahangarnokolaei chemicals. Natural coagulation has been used for et al., 2017). Electrocoagulation requires very small treating wastewater from various industries like settling time due to the rapid settling of the flocs and textile(Muralimohan et al., 2014; Shankar et al., 2014; results in lesser sludge production (Ahangarnokolaei Dotto et al., 2019; Prabhakaran et al., 2020), dairy et al., 2017). However, complicated experimental (Sivakumar et al., 2014; Sivakumar, 2015; Sivakumar setup with the electricity or current input is required et al., 2016; Triques et al., 2020), tannery (Ahmed et for the treatment which limits its commercial al., 2020), etc. A compilation of the various chemical application by increasing the operational cost of and natural coagulants used for the treatment of the treatment unit (Perren et al., 2018). Therefore, industrial wastewater, from literature studies, has electrocoagulation cannot be seen as an economical been provided in Table 1. option for a large-scale industrial wastewater In comparison, some of the synthetic coagulants treatment. Coagulation, on the other hand, is an used for the treatment of domestic sewage include important chemical treatment method and is very alum (Sarparastzadeh et al., 2007), ferric chloride effective for wastewater treatment (Carballa et al., (Sarparastzadeh et al., 2007), poly-aluminium 2005). Wastewater streams obtained from industries chloride (El Samrani et al., 2008) and aluminium like tannery (Ariffin et al., 2009), hospital (Wang et sulphate (Fabres et al., 2017). Several research studies al., 2011), paper and pulp mill (Wang et al., 2011), have shown the potential of natural coagulants in etc. have been treated by coagulation using synthetic treating the wastewaters originating from different chemicals. The use of chemical coagulants for industries and have shown them to be equivalent coagulation of wastewater has various implications to chemical coagulants in terms of treatment such as their potential to cause diseases (WHO efficiencies for various parameters of interest. Guidelines, 2010), the possibility of groundwater