Waste Bioremediation

Incomplete discharge of waste materials into the environment is of concern due to its slow degradability, highly soluble and biomagnification features in animals and plants. Conventional treatment techniques include chemical precipitation, ion-exchange, reverse osmosis and combustion are effective but energy intensive and consumes huge amounts of chemicals which may give rise to secondary problems such as spillage, corrosion and toxicity. The application of biological approach notably from use of microorganisms is an interesting alternative. Microorganisms such as bacteria, yeast and algae are known to survive in waste-containing environments owing to its ability to reduce, accumulate, sequester, absorb and oxidize different types of waste materials into forms, mostly making it less soluble and easily precipitated, that is, less toxic to the environment. This monograph covers biological approaches to remediate waste generated from various industries such as petroleum, electronic, textile, electroplating and landfill site(s). The role of microbes in composting and anaerobic digestion processes is also discussed. Apart from this effectiveness of microbes living in legumes of plant to remediate toxic heavy metals are also reported.

This chapter presents an overview on microbial fuel cells (MFCs) as a novel electrogenic reactor systems for simultaneous treatment of wastewater and generation of bioelectricity. MFCs work on the principle that organic matter present in wastewater serves as a primary substrate for the bacteria to consume and release electrons, facilitating the treatment of wastewater with simultaneous generation of power. Microbes in the anode chamber generate protons (H⁺) and electrons (e⁻) through reactions by decomposing the rich organics present in the wastewater and in the process treating the wastewater and producing a value added product which is bioelectricity. When these protons travel through the membrane and the circuit, respectively, power is generated from the system. Given the non-renewable aspect and polluting nature of fossil fuels, MFCs have generated interest among several research communities around the world. Following a historical approach toward this technology, the chapter discusses the various types of microbial fuel cells prevalent and compares the different MFC designs used. The role of proton exchange membrane separating the anodic and cathodic chambers is also explained. It focusses on the principle and working of an MFC and describes the instrumentation and procedure for reporting data. Additionally, the chapter presents benefits, drawbacks, and future scope of research in this field.

This chapter highlights and discusses the important research studies that have been carried out previously on sulphate removal from wastewaters under anaerobic conditions. Moreover, the role of electron donor addition on biological sulphate reduction and the beneficial role of sulphate-reducing bacteria (SRB) are reviewed in this chapter. This chapter describes the fundamentals of the anaerobic sulphate reduction process, the factors affecting biological sulphate reduction and the different bioreactor configurations used for sulphate removal from wastewater.

Depolymerization is a tertiary recycling technique which represents the transformation of polymer chain into monomer units along with oligomers. Depolymerization of polymers with heterofunctional groups can be targeted by microorganisms, especially by fungi. Polyethylene terephthalate (PET), polyurethane (PU), polyester are among such polymers. Hydrolysis is the main cause behind microbial degradation, and hydrophobic surface binding of involving enzyme is responsible for microscopic description. Microbial participation techniques can be modified by using a chemical-assisted hybrid technique, and even halogenated polymer is dechlorinated by this technique.

Bioremediation or microbial cooperation can improve the e-waste management process in a greener way. Every management strategy is concentrated upon the organic and inorganic portion of the e-waste. Organic part consists of variety of thermo and thermosetting plastic with the presence of halogenated material. Microbes are involved in the process of dehalogenation in many ways. Microbes can manage the leaching of inorganic portion of e-waste which consists of both metallic and nonmetallic components.

Wastes generation and contamination are increasing drastically due to industrial activities and population growth. Many approaches are in place such as chemical and physical treatments to tackle these wastes and contamination. However, other means of remediation are necessary to overcome the challenges in wastes treatment. In the last decades, research in bioremediation has increased dramatically owing to its potential application in cleaning up all kinds of waste from soil and other contaminated areas. Numerous plants and microorganisms prove to be efficient for bioremediation for various kinds of wastes such as metal, nuclear, mineral, fuels, and chemicals. Among them, vetiver grass could play pivotal role as bioremediation agent for numerous waste categories. Originally being a native from India, vetiver perennial grass has spread to the tropical and subtropical parts of the world due to its application in various fields, such as soil conservation, fragrance, energy fuel, handcrafts, hedge formation, medicinal preparations, and carbon sequestration. The unique property of vetiver plant is their ability to grow in harsh conditions and absorb contaminants leading to remediation. Therefore, several research studies reported on bioremediation potential of vetiver grass among other potential application. In this study, a review of these studies is carried out to highlight the benefits and the limitation of vetiver in bioremediation across industries and to provide some insights on how to incorporate vetiver grass in industries, municipalities, and households in the current and future wastes remediation programs that demand a sustainable approach.

Management of organic solid waste through composting is the sustainable option to prevent leachate and greenhouse gas emissions after disposal/landfilling. Composting reduces a maximum of 65% of the initial volume and also recovers nutrient-rich end product. During composting, the biodegradable organic carbon, micropollutants, and nuisance gases from the organic fractions are biologically transformed into a stabilized product. Millions of indigenous microbial populations act to degrade the waste by releasing off high temperature and gases. The process is largely influenced by the aeration rate, moisture content, C/N ratio, temperature, particle size and volume of the waste material composted. The active thermophilic phase of the composting determines the rate of waste degradation and organic matter transformation during the process. During composting, the waste material undergoes three different temperature phases: (a) initial moderate temperature (less than 40 °C) for a couple of days, (b) the thermophilic temperature (over 40 °C) for few days to several weeks, and finally, (c) the cooling and maturation phase. During the process, the organic carbon and nitrogen are metabolized to moisture, CO_2, and other nitrogen gases, significantly reducing the availability of exchangeable carbon and heavy metals in the compost. Furthermore, it also increases the bioavailability of essential plant nutrients total nitrogen (N), ammonium (NH₄), phosphate (P₂O₅), and potash (K₂O), and other micronutrients. The release of heavy metals and potential gases during composting is unavoidable, but it can be controlled by adding appropriate bulking agents such as sawdust, dry leaves, wood chips, and optimizing the above-mentioned process parameters. This chapter focusses especially on organic wastes and pollutants reduction through composting. Also, the major influencing factors and process parameters for effective composting of organic waste and treatment of pollutants gases emitted during the process are discussed.

The increasing industrial demand for remediating the textile wastewater in an effective way has led to the pervasive acceptance of bioremediation. Bioremediation techniques such as bioaccumulation, biosorption, bioaugmentation, and biodegradation utilize the biological systems to treat the textile effluents containing the recalcitrant dye molecules. Bioremediation is known to be environmentally reliable and is an alternative to the conventional decomposition techniques with the prerequisite to fulfill the efficacy and economic viability. Among the aforementioned bio-remedial measures, biodegradation of the textile dyes is the trustworthy industrial application. Biodegradation of dyes can be achieved using single bacterial strains and co-cultures/consortia. The consortial systems are proven to be advantageous over a single strain as they involve an inductive synergistic mechanism among the co-existing strains. As a result of this co-metabolism, there is a formation of different intermediate metabolites such as toxic aromatic amines which are furthermore mineralized by the other bacterial strains in the consortia.

Nowadays pollution control and abatement are critical issues faced by environmental scientists due to rapid industrialization. Petroleum industry is one of the major industries which release hydrocarbon pollutants in environment. Polycyclic aromatic hydrocarbons (PAHs) are the priority pollutants which are released into the environment by exploration activities of petroleum industries. The indiscriminate accumulation of petroleum hydrocarbon pollutants can be hazardous to the human life and aquatic biota. Due to toxicity of these pollutants, establishing efficient and environment-friendly method to degrade and detoxify these pollutants is an important research challenge. Various physiochemical methods are applied all over the world to remediate of petroleum hydrocarbon pollutants. Bioremediation technique has been developed for treatment of crude oil pollutants using biological agents like bacteria, fungi, algae, and plants. Applications of certain microorganisms have gained importance in the field of applied environmental microbiology. The application of microbes to degrade pollutants is getting attention due to its environmental and economic benefits. They can be used to change bioavailability and toxicity of petroleum hydrocarbons present in polluted soil and aqueous environment. This paper explores hydrocarbons present in petroleum crude. The effect of petroleum hydrocarbon pollutants on human health and environment is also discussed. This chapter also explains microbial degradation of these pollutants.

Hexavalent chromium is one of the toxic heavy metals considered to be potentially harmful for life of a wide range of organisms, including human life, due to its high mobility in soil and water media. Wastewaters containing chromium(VI) are produced from different sources including many industries such as electroplating, leather tanning procedures, and chromite ore processing. When these practices are not conveniently regulated, contamination problems associated with irresponsible waste disposal of effluents appear in the surrounding environments, such as water bodies and sediments. Conventional treatment of chromium(VI) implies its reduction to chromium(III)—a less toxic species—and its later precipitation. This process can be carried out through widely known physicochemical techniques although it is expensive mainly when low concentrations of the pollutant need to be treated. Microorganism-based techniques are considered very cost-effective alternatives, especially for the first step of the treatment, i.e., chromium(VI) reduction. Isolation and identification of chromium(VI)-resistant and chromium(VI)-reducing strains are fundamentally significant for this purpose. Microorganisms capable of living when exposed to high temperatures seem to be great candidates for bioremediation applications due to the increase of the speed of the process. The objective of the present chapter is to study thermophilic chromate-resistant and chromate-reducing bacteria toward Cr(VI) bioreduction. Cr(VI) removal by immobilized bacterial cells and their advantages are also summarized for a better understanding on how to transfer this technology from laboratory to a large-scale application for wastewater treatments. An example of bioreduction of chromium(VI) by immobilized bacteria isolated from the geothermal area of Domuyo (Neuquén-Argentina) is presented as case study.

In the present scenario, management of heavy metals discharged from industrial effluents has become one of the consequential environmental challenges. Conventional effluent treatment methods are very expensive and generate hazardous sludge. Biosorption using microbial sources is a promising eco-friendly alternative for heavy metals removal. In the past few decades, filamentous fungi, Aureobasidium pullulans, have gained attention due to its high biomass generation, easy upscaling, and its tolerance toward heavy metals than other fungal species. Aureobasidium pullulans is nonpathogenic microorganism used in food, cosmetics, and pharmaceutical industries. This chapter focuses on morphology, mode of sequestration, and accumulation of various heavy metals by A. pullulans.

Increasing landfill sites leads to serious environmental problems due to the generation of leachates. Leachates are the potentially hazardous waste from landfill sites and consist of many organic and inorganic, dissolved suspended, biodegradable or non-biodegradable matters. In this chapter, we are discussing various process involved during landfill biodegradation, generation of leachate and factor affecting biodegradation process. Microbes played an important role in the biodegradation and bioremediation of landfill waste and leachates. The different kind of microbes used organic material present in landfill and leachate for their metabolic activities and resulted in the production of gases like CH₄ and CO₂. The biodegradation processes of waste material depend on the various factors including characteristics of waste materials, moisture content, temperature, pH and the presence of inhibitors.

In natural environments, the average abundance of heavy metals is generally low and much of that sequestered in sediments, soil and mineral deposits may be biologically unavailable. Microorganisms have ability to adapt and live in all ecological condition. In natural habitat, the cause for microbes on heavy metal depends on the physico-chemical properties of the environmental condition. Microbes can metabolize the metal ion and yield energy through oxidation and reduction process by dissolving them. Many trace metals are necessary for growth and metabolism at low concentrations, (e.g. Co, Cu, Ni, Mo, Fe, Zn), and microorganism acquires mechanisms of varying specificity for the intracellular increase from the external environment. The molecular mechanism of microorganism and plants in the removal of toxic heavy metals into nontoxic form using plants and microorganisms is well studied, and this has many biotechnology implications in the bioremediation of heavy metal contaminated sites.

Technological advancement has greatly increased the demand for newer lithium-ion batteries (LIBs) due to the more use of advanced energy storage devices like electric vehicles, consumer electronics, renewable energy storage, backup power, medical devices. The existing methods for metal recovery from LIB recycling involved: (i) aqueous stream-based limited recycling using the liquid stream mixed with soda ash with the hammer mill and shaker table (ii) supercritical CO₂-based recycling of cathode and anode (iii) pyro- and hydrometallurgical processes. Microbial participation for the recovery of metals from waste (LIBs) was found to be an attractive method due to its environmental-friendly approaches. Lysinibacillus, Micrococcus, Sporosarcina, Empedobacter, Barrientosiimonas, Lysinibacillus, Paenibacillus, Bacillus, Acidithiobacillus are among the species involved in the recycling of metal form LIB.

In India, a large portion of the landfill is open or unlined. The administration of municipal solid waste (MSW) requires proper infrastructure, upkeep in all actions. This turns out to be extremely costly and complex due to the unconstrained improvement of urban dominion. The landfill has been concerned with air contamination, soil contamination, surface and groundwater contamination. The origin of landfill gases is subjective to various factors such as the composition of solid waste product, decomposition of waste, oxygen availability, moisture and rain percolation, pH, organic amount and microorganism population. Dioxins are exceedingly dangerous and can cause reproductive and developmental problems. The waste put in the landfills influences the groundwater stream, and rainwater may permeate through the waste. The water gets mixed with organic and inorganic compounds and accumulated at the bottom of the landfill. The present study represents a real-time case study of a solid waste dump yard located at Saduperi, Vellore District, Tamil Nadu, India. Groundwater samples are collected in and around landfill site to analyse the possible impact of leachate on the quality of groundwater. Various physicochemical parameters and heavy metal concentration of groundwater and leachate sample are analysed and reported. Leachate analysis showed a neutral pH (7.4) and BOD concentration of 9100 mg/L. Total hardness and alkalinity were found to be 5500 and 10,000 mg/L, respectively. The chloride concentration was found to be higher (5317.5 mg/L). The concentration of heavy metals such as nickel, cadmium and chromium was found in concentrations of 0.05, 0.09 and 2.84 mg/L, respectively. Groundwater samples showed slightly acidic to neutral pH values with higher concentration in TDS (9690 mg/L) and chloride (2153 mg/L) parameters. Further leachate pollution index was calculated to know the potential of impact from the dump site leachate.

Chromium pollution is increasing ceaselessly due to unending industrialization. Of the various oxidation states, Cr⁶⁺ is highly detrimental due to its mutagenic and carcinogenic nature. Lack of effectiveness of various conventional methods due to economic and technical constraints resulted in a search for an eco-friendly and cost-effective biological techniques for Cr⁶⁺ removal from the soil. Phytoremediation came up as an innovative technique to address the problem. However, the effectiveness of phytoremediation process is greatly hindered in high metal contamination environments. Recently, microbial-mediated plant stress improvement has occurred as a major element of metal stress management in plants, and their role in enhancing plant growth and improving phytoremediation process has been well studied. The inoculation of plants with metal-resistant plant growth-promoting rhizobacteria (PGPR) plays an important role in enhancing the efficiency of heavy metal phytoremediation. PGPR improves the plant growth through innumerable mechanisms, such as production of siderophores, solubilization of mineral nutrients, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and phytohormone production. These microbes transform heavy metals into soluble and bioavailable forms, hence facilitates metal removal through phytoremediation. Correspondingly, application of plant growth-promoting bacteria exhibiting Cr⁶⁺ reduction potential when used as an inoculant with phytoremediation plant may result in improved plant growth and chromium remediation efficiency. This chapter focuses on the Cr⁶⁺ remediation potential of PGPR through metal–microbe–plant interactions.

Biomining is the way towards removing significant metals from minerals and mine tailings with the help of micro-organisms. This process has emerged as an innovative biotechnological approach for extracting the essential metals from low-grade ores. Micro-organisms are utilized to filter out the minerals, instead of the ancient strategies including utilization of outrageous temperature or toxic chemicals, for example simmering and purifying, which adversely affect the earth and furthermore expensive. Many industries have now turned to biomining due to low production cost and high yield maximum to 90%. The need emerges from recent patterns in the industries: progresses with the consumption of high-review mineral assets, the subsequent inclination for mining to be amplified further underground, the developing familiarity with ecological issues related with the purifying of sulphide minerals and the consuming of sulphur-rich fossil energizes and the increasing expense of the huge measures of vitality required in the routine recuperation techniques. Natural resources are assets that exist without activities of mankind. Natural resources can be segregated as biotic and abiotic natural resources. Biotic natural resources include all living creatures on earth including flora, fauna, vertebrates and invertebrates. Abiotic natural resources include all minerals such as gold, copper, iron. Biomining will turn out to be more vital as high-review surface mineral stores are worked out and turned out to be less feasible and mining organizations will be compelled to discover other mineral assets. Biomining can without a doubt give such a green innovation to adventure natural mineral assets.

Anaerobic digestion (AD) is a biological decomposition process that occurs in the absence of oxygen. The decomposition of organic matter is a multi-step process of series and parallel reactions namely hydrolysis, acidogenesis, acetogenesis and methanogene. Most of the control in anaerobic digestion is undertaken directly by the microorganisms themselves; however, the operational conditions such as temperature, pH, essential trace nutrients and toxicants can play a major role in modifying reaction rates of individual sub-processes. The energy performance of the anaerobic digestion is depending mainly on the biogas production technology, raw materials and geographic location (ambient temperature). Since the feedstocks coming to anaerobic digestion have usually lower heating value as received, the usual energy efficiency calculation used for incineration plant is not useful. Most commonly used method is the input/output method, and the estimation is dependent upon the chosen system boundary.

Adequate sanitation and hygiene practices are essential for maintaining the good health. In developing countries, rapid increase in population and urbanization has put tremendous pressure on the existing infrastructure related to the sanitation, thereby necessitating development of more effective technologies. Among the sanitation practices, proper disposal of human excreta assumes much significance as it is one of major sources of human pathogens. Various technological solutions are available for treatment of human fecal matter. Employing the principles of anaerobic biodegradation, biodigester technology has been developed by Defence R&D Organisation, India, for effective decomposition of human fecal matter under varied geoclimatic conditions. The present article deals with the biodigester technology, its uses, and possible impacts on overall sanitation scenario in India. Chemistry and biology of anaerobic degradation of nightsoil using a unique anaerobic microbial inoculum and a bioreactor are also discussed. In addition, we highlight the factors governing the biodegradation efficiency, effluent quality as well as possible recycling/reuse of water and harvesting, and use of methane generated from it. Also, based on the critical and in-depth analysis of existing scientific information, we further deliberate on future prospects of this technology for sustainable and ecofriendly treatment of nightsoil in developing countries.