Removal of pharmaceuticals and personal care products (PPCPs) from wastewater: A review

Highlights

• The removal of PPCPs from wastewater was reviewed.

• Analytical methods for 87 commonly used PPCPs were summarized.

• Tables summarizing the biological and chemical processes were provided.

• Suggestions were made for further study.

Abstract

The pharmaceutical and personal care products (PPCPs) are emerging pollutants which might pose potential hazards to environment and health. These pollutants are becoming ubiquitous in the environments because they cannot be effectively removed by the conventional wastewater treatment plants due to their toxic and recalcitrant performance. The presence of PPCPs has received increasing attention in recent years, resulting in great concern on their occurrence, transformation, fate and risk in the environments. A variety of technologies, including physical, biological and chemical processes have been extensively investigated for the removal of PPCPs from wastewater. In this paper, the classes, functions and the representatives of the frequently detected PPCPs in aquatic environments were summarized. The analytic methods for PPCPs were briefly introduced. The removal efficiency of PPCPs by wastewater treatment plants was analyzed and discussed. The removal of PPCPs from wastewater by physical, chemical and biological processes was analyzed, compared and summarized. Finally, suggestions are made for future study of PPCPs. This review can provide an overview for the removal of PPCPs from wastewater.

Introduction

Pharmaceutical and personal care products (PPCPs) have been widely used in many fields such as medicine, industry, livestock farming, aquaculture and people's daily life. They are becoming ubiquitous in the environments due to their extensive applications and poor removal by the conventional biological wastewater treatment plants. They can be classified into several classes based on their various purposes (Daughton and Ternes, 1999). The specific classes, corresponding purposes and main properties of PPCPs were listed in Table 1. PPCPs have been received increasing attention since 2000s. The worldwide production of PPCPs was over 1 × 10⁶ tons in 1993 (Daughton and Ternes, 1999). In 2003, the annual production of penicillin was 28,000 tons amounting 60% of the world total consumption of antibiotics (Richardson et al., 2005). Antibiotics contain more than 50 products (Mompelat et al., 2009), and penicillin is just one of the antibiotics. Although their assumption is not accurate, PPCPs have many classes, and each class includes many products. The annual production of PPCPs can be higher than 2 × 10⁷ tons. Moreover, this production still increases due to the high demands of PPCPs in preventing or curing disease and sustaining the development of economic such as aquaculture and livestock farming. Consequently, environmental pollution caused by extensive application of PPCPs is becoming more and more serious.

Nowadays, the rising attention from the world has been paid to the fate of PPCPs in the environment, which can be attributed to the two reasons. One reason is the ubiquity of PPCPs in the environment resulting from their widespread use; the other reason is the progress in analytical technology, which enables people to detect PPCPs in trace level.

The PPCPs can be introduced into the environment by direct and indirect pathways. The way of PPCPs entering to the environment was reviewed by Mompelat et al. (2009). Briefly, PPCPs can enter the surface water via directly discharging into the surface water by industries, hospitals, households and wastewater treatment plants and through land runoff in case of biosolids spread on agricultural land, which can reach the groundwater by leaching or bank filtration. Within the surface water compartment, sediment can adsorb the PPCPs because it has a variety of binding sites (Kästner et al., 2014). Soil can be also one of the sink for PPCPs. PPCPs can pass into the soil by the irrigation with the treated or untreated wastewater containing PPCPs. In addition, for some PPCPs, they can transfer to soil by atmospheric wet deposition (Kallenborn et al., 2004).

Many studies have shown that PPCPs occurred in the surface water with the concentration ranging from ng/l to μg/l (Calamari et al., 2003, Moldovan, 2006, Kasprzyk-Hordern et al., 2008, Huerta-Fontela et al., 2011, Wu et al., 2015, Roberts et al., 2016), in the ground water at concentration level of ng/l to mg/l (Cabeza et al., 2012, López-Serna et al., 2013), in sediment with the concentration reaching μg/kg (Richardson et al., 2005) and in soil achieving μg/kg (Karnjanapiboonwong et al., 2011, Gottschall et al., 2012).

The advance in the development of analytical technology enables people to detect PPCPs in trace level. Improvement of extraction method combining with advanced analytical techniques, such as gas chromatography-tandem mass spectrometry (GC-MS/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), significantly increases the ability to detect the distribution of PPCPs in the environment.

PPCPs are recognized as pseudo persistent organic pollutants in the environment, which may display the same risk to the environment as the truly persistent organic pollutants due to their continuous introduction into the environment by means of different ways such as sewage treatment plants. Although the concentrations of PPCPs in the environment are very low as aforementioned, they still can affect water quality and ecosystem balance, and even impact drinking water resources. Studies have been conducted to investigate the environmental risk of PPCPs by comparing the difference between predicted concentration and measured concentration or predicting the adverse effect concentration with regard to specific organisms (Hernando et al., 2006, Verlicchi et al., 2014), which provided theoretical basis for determining the environmental risk of PPCPs. In addition to the comparison between the predicted and measured concentration or the effect on the specific organisms, the environmental risk of PPCPs was also characterized in terms of bioaccumulation, toxicity and persistence (Mendoza et al., 2015). In order to eliminate the potential risk of the PPCPs, it is necessary to get rid of the PPCPs from wastewater. As a result, many methods including physical, chemical and biological methods have been developed to remove the PPCPs during the wastewater treatment plants (WWTPs).

The objective of this paper is to review the current knowledge on the removal of PPCPs from the wastewater, as well as the analytical techniques used to determine the PPCPs in the environment.