1. Introduction

Pharmaceutical wastewater is one of the most important gateways of emerging pollutants (such as synthetic hormones including corticosteroids) to enter water bodies. During the last years, numerous studies have documented the presence of many of these substances at the level of microgram or nanogram per liter in raw water (i.e., stream/source water), in wastewater effluents, and even in finished drinking waters [1, 2]. As a consequence, pharmaceuticals are entering in the trophic chain and causing adverse ecological and human health effects [3].

An important reason why so much care is taken with pharmaceutical products is that they have to produce a biological effect. They are made as stable as possible so that they can be stored for a long time and easily swallowed. The membranes are lipophilic enough to cross the membranes, and in order to reach the sites of action—especially those taken orally—drugs must be resistant to enzymes and must not hydrolyze at acidic pH values. They must be stable

Efficient Removal Approach of Micropollutants in Wastewater Using Membrane Bioreactor

http://dx.doi.org/10.5772/intechopen.75183

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Because of these properties, active pharmaceutical ingredients/conversion products can be

The intake of drug active substances occurs in various ways. Starting from humans and animals, the active pharmaceutical ingredients reach the wastewater, soil, and groundwater and, if adequate treatment is not done, reach our drinking water. Pharmaceutical products can be roughly divided into two: medicinal products and veterinary drugs used by humans. Veterinary medicines are used in farm animal breeding and poultry production. Medicinal products used by humans reach sewage through urea and feces and from there to wastewater treatment plant. If xenobiotics are taken as an example, there are three possible behaviors of the substance: (i) the substance is completely mineralized to water and CO2 (e.g., aspirin). (ii) The substance is lipophilic and does not easily fragment. So, some of the material is kept in clay. (iii) The substance is metabolized to a more hydrophobic than lipophilic form but becomes resistant. It cannot be removed in the treatment plant, and it is thrown away with wastewater and mixed with the receiving waters. If the metabolites are still biologically active, they also affect the aquatic organisms in the environment. Possible materials in clay, if the mud is laid on the field, may affect microorganisms and the useful ones. Medicinal substances used to support growth of animals in the stables are mostly fertile. These substances can affect soil organisms. The hydrophilic materials in the sewage sludge, which are scattered in the mouth,

Pharmaceutical substances used for animals in the field are thrown directly to the ground via urea and feces. High local concentration affects soil organisms. It is also possible that medicinal substances spread over the surface are mineralized to the ground or reach the groundwaters.

They are used in fish farms and are directly confused with the receiving waters because the best way to treat fish with antibiotics and other medicines is to use feed additives. Because most of the feed additives are not eaten by the fish, they fall from the cages and accumulate in the seabed. These substances can affect aquatic organisms. An unknown part of the medical goods sold for human use is thrown into the toilet as waste by people and reaches the

Micropollutants consist of a vast and expanding array of anthropogenic as well as natural substances. These include pharmaceuticals, personal care products, steroid hormones, industrial chemicals, pesticides, and many other emerging compounds. Micropollutants are commonly present in waters at trace concentrations, ranging from a few ng/L to several μg/L. The "low concentration" and diversity of micropollutants not only complicate the associated detection and analysis procedures but also create challenges for water and wastewater treatment

bioaccumulated and can cause effects in aquatic or terrestrial ecosystems.

reach the aquatic environment by infiltrating with rain [11–13].

treatment plant by interfering with the sewage system [14–17].

processes [2].

and have high mobility in liquid phase [11–13].

Pharmaceuticals are not regulated at the moment in the EU, but the 2013 amendment of the Environmental Quality Standards Directive (2008/105/EC) contains a mechanism to collect high-quality data on concentration of compounds of environmental concern, the so-called watchlist. This list includes diclofenac, 17-beta-estradiol (E2), and 17-alpha-ethinylestradiol (EE2). For compounds on this list, it is likely that regulations will be developed in the future. This would mean that additional treatment of wastewater will be necessary to comply with these regulations [4].

Membrane bioreactor (MBR) technique is a promising alternative to conventional treatment, [5, 6], and its usage is increasingly for municipal wastewater treatment and reuse, and great concerns have been raised to some emerging trace pollutants found in aquatic environment in the last decade, notably the pharmaceuticals [7]. In that sense, recently a pilot MBR was innovatively applied leading to removal efficiencies over 95% of the chemical oxygen demand (COD). Furthermore, other lab-scale MBR studies have been focused not only in the removal of the bulk organic matter but also in the elimination of the specific organic micropollutants present in the raw wastewater [1].

In this study, we present a comprehensive review of the studies carried out in the literature with MBR of micropollutant residues in different wastewaters, and it is expected that these pollutants, which are highly biologically active and difficult to biodegrade, shed light on treatment strategies to improve biodegradation.
