Efaq Ali Noman

Removal of heavy metals and antibiotics from treated sewage effluent by bacteria

The increased loads of antibiotics and heavy metals in sewage lead to bacterial cells acquiring resistance to both heavy metals and antibiotics. Therefore, these bacteria can play an important role for removal of pollutants from sewage. The utilization of the microbial processes such as biosorption and enzymatic biodegradation processes has increased during the recent years. These processes are significantly inexpensive and eco-friendly. Enzymatic techniques known as white biotechnology have the ability to degrade complex compounds. Hence, these can be applied to industrial processes. In the current review, the removal of heavy metals and antibiotics from treated sewage effluents by heavy metal/antibiotic-resistant bacteria will be discussed.

Consequences of the Improper Disposal of Greywater

Discharge of greywater into the environment and natural water bodies is the main challenge in the management of greywater. The increase of greywater disposed into the environment has drawn serious attention from the society and the government who endeavour to find a safe alternative way for the disposal of these wastes. The implication for the improper disposal of greywater is associated with infectious agents. This is because the organisms are able to multiply in the environment and might reach the infective dose which causes several diseases in human and animals. In this chapter, the health risks and effects posed by pathogens and heavy metals in disposed greywater to the environment and humans are reviewed. The chapter discusses the level of risk for each component in greywater. It has appeared that eutrophication and water bloom are associated with the discharge of greywater into the natural water due to the high level of nutrients.

Determination of Pathogens in Greywater

There are many methods used for isolation and the enumeration of pathogenic organisms. The direct methods depend on the culture medium and microscopic examination. However, these techniques are not effective for all pathogenic organisms in the environment since many organisms require a specific condition to grow on the culture medium. Therefore, the using of enrichment methods might exhibit more efficiency in the determination of pathogens from the wastewater samples. The main challenge in the microbiological assessment of greywater lies in finding the most effective method to detect the presence or absence of pathogens which are available in low concentrations. In this chapter, traditional methods including direct culture and enrichment methods are reviewed.

Disinfection Technologies for Household Greywater

The treatment technologies for greywater are followed by the disinfection processes in order to achieve safe disposal into the environment. The disinfection technologies aim at reducing or minimising the concentrations of the pathogenic microorganism of greywater which have a high potential risk for humans and plants, and, thus, provide safe and aesthetically acceptable greywater that is appropriate for the purpose of irrigation. The disinfection processes include chemical (chlorination and ozonation), physical or mechanical (filtration process) and radiation disinfection (UV irradiation, solar disinfection (SODIS)). The degree of the disinfection process proposed must take into account the type of reuse and the risk of exposure to the population. In this chapter, the disinfection techniques of greywater are reviewed and discussed based on their efficiency to eliminate the pathogenic bacteria and other toxic by-products. The objective of this chapter was to discuss the advantages and disadvantages of disinfection processes. Among the several disinfectant technologies for greywater, SODIS appears to be the most potent technology which is widely applicable in most of the developing countries experiencing arid and semi-arid atmospheric conditions due to the high density of sunlight which is more effective for inactivating pathogenic microorganisms.

Treatment Technologies of Household Greywater

The shortage of water resource in the developing countries induced the search for alternative sources. Greywater alongside storm and ablution water might represent the best source of water because these waters have less contaminant than sewage. However, the separation of this water from the source point is the first step in the proper management which facilitates the treatment process. The selection of treatment technologies for greywater depends on the economic status and standards limits required for disposal or reuse of greywater which differs from one country to the others. In many of the developing countries, the treatment of greywater aims at achieving the basic requirements which lie in the reduction of the main parameters of greywater. The utilisation of flocculation and coagulants process might be effective for this purpose. Many of the natural coagulants have been reported to reduce the main parameters of greywater. In the developed countries, advanced technologies are used for removing of xenobiotics organic compounds (XOCs) and to produce high quality of the treated greywater. This chapter focuses on the treatment technology used for the treatment of greywater and their efficiency in the reduction of XOCs.

Recycle of Greywater for Microalgae Biomass Production

The potential of greywater to be used as a production medium for biomass lie in the high concentrations of nitrogen and phosphorus as well as the organic matter necessary for microalgae growth. Microalgae have high potential to adapt and utilise nitrogen, phosphate and other nutrients available in wastewater. Other factors which affect the production of biomass in microalgae include light, temperature, aeration and mixing. The effect of pH might also contribute to the quality and quantity of the produced biomass. The critical step in the production of biomass lies in the harvesting of microalgae cells, extraction of the lipids, proteins and carbohydrates. The objective of this review was to identify the criteria required for selecting greywater as a production medium and microalgae species. The harvesting and extractions techniques used in this process are also discussed and also the quality of the produced biomass and the further utilisation based on the toxicity, nutrients values and microbiological aspects.

Bioremediation of Xenobiotic Organic Compounds in Greywater by Fungi Isolated from Peatland, a Future Direction

The conventional wastewater treatment processes aim to remove pathogens and priority pollutants in terms of chemical and physical characteristics such as chemical oxygen demand (COD), biological oxygen demand (BOD) and total suspended solids (TSS). Some of the technologies are used for reduction of nutrients such as the phycoremediation process which has high efficiency for the reduction of total nitrogen and phosphorus from the wastewater. Unfortunately, these techniques have no contribution to the removal of XOCs. The greywater with XOCs should be subjected to an advanced treatment process to remove xenobiotic organic compounds (XOCs) before the final disposal into the environment. The current treatment by the oxidation processes is insufficient and expensive as well as have many of toxic by-products. This gap offered the investigators greater opportunities to explore effective and eco-friendly alternative technologies for XOCs degradation in greywater. Moreover, many of the fungi from the peat soil especially that belong to white rot fungi have higher enzymatic activities and produce a lot of oxidative enzymes such as laccase, lignin and manganese peroxidases. These enzymes are the main factor in the bioremediation process of the pollutants in the contaminated environment such as wastewater. Among different types of the oxidative enzymes from the fungi, the peroxidase and laccase have high importance in the biodegradation of XOCs. The current chapter discusses the potential of fungi as an alternative green technology for the degradation of XOCs from the greywater.

Reuse of Greywater for Irrigation Purpose

Reuse of greywater for the irrigation is an alternative water source in the new water management strategy of the countries that face a severe deficiency of water resources such as the Middle East Countries. Several studies have been evaluated the effects of greywater on the soil structure and plants. Greywater with a high level of nitrogen and phosphorus as well as macro-elements induce the plant’s growth. However, the reuse of these effluents at excessive rates might produce detrimental effects on soil and crops. Some of the heavy metals in the greywater are toxic to plants, while others have toxicity for human and animals. The main consideration in the reuse of greywater in the irrigation lies in the transfer of pathogenic microorganisms to humans directly or indirectly. In developed countries, the utilisation of greywater for the irrigation subject for strict regulation which lies in the method of irrigation as surface or subsurface. In contrast, the surface irrigation is the common practice in the developing countries. In this chapter, the benefits of the greywater for the soil and plants as well as the adverse effects are reviewed. Based on the literature review in this chapter, it can be concluded that the criteria required to reuse greywater in the irrigation include aesthetics, hygienic safety, environmental tolerance, and technical and economic feasibility.

Phycoremediation: A Green Technology for Nutrient Removal from Greywater

Phycoremediation as a green technology relies on microalgae which have high potential to grow in greywater. The presence of high levels of nutrients is necessary for microalgae growth to improve the efficiency of this process. However, the main consideration of the phycoremediation process of greywater lies in the wastewater composition, the selection of microalgae strains with high potential to compete with the indigenous organisms in the greywater and remove nutrients and elements from greywater as well as microalgae, which possess the ability to survive under stressful environmental conditions. Besides, this process can be applied to individual houses. The cost of the phycoremediation process, source of microalgae and energy required are the main points which need to be discussed further. The study indicated that the phycoremediation process is most effective for the treatment of greywater. However, many aspects have to be evaluated in order to achieve the high-quality-treated greywater. In this chapter, the effectiveness of phycoremediation and the mechanism of nutrient removal are discussed. Most microalgae species exhibited greater efficiency in removing nitrogen compared to phosphorous due to the nature of the anabolic pathway of microalgae cells and the ability of nitrogen compounds to diffuse through the cell membrane faster than phosphorous compounds.

Xenobiotic Organic Compounds in Greywater and Environmental Health Impacts

One of the most common organic compounds which represents real challenges in the environmental pollution treatment is the xenobiotic organic compounds (XOCs). They are complex organic compounds which have high persistence in the environment extend for several years due to their chemical structure. Meanwhile, its hazards risk lies in tier active poisons which directly affect aquatic life within a short exposure time. XOCs in the greywater are generated from utilisation of detergents and personal body care products and they have the potential to persist in nature for a long time and thus have long-term effects to the environment including toxicity and bioaccumulation in the organism’s cells. There are many literatures discussing about the types of XOCs of greywater. For instance, some types of XOCs in greywater are toxic for aquaculture. This chapter will discuss the occurrence of XOCs in the greywater, chemical structure and bioassay for the toxicity of these compounds.