Evaluation of Hospital Wastewater Treatment Using Sewage Treatment Plant for Heavy Metals, Radionuclides, and Some Pharmaceuticals: A Case Study

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Introduction
Hospital waste water (HWW) is considered highly toxic as it contains microorganisms, pharmaceuticals, heavy metals, radionuclides, halogenated organic compounds, disinfectants, pigments, dyes, genotoxins, cytotoxins, and drug metabolites, some of which are environmentally persistent and pose a direct threat to the environmental and public health [1,2].HWW contains heavy metals from feces, medicine, and food supplements ingested by patients, as well as cleaning agents, paints, utensils, and equipment wear [3].Silver is used in X-ray film development, while manganese, gadolinium, and iron are involved in diagnostic magnetic resonance imaging (MRI).Some heavy metals are used for medical treatment purposes such as zinc, tungsten polyoxoanions, cisplatin, and boron [3].Metals such as iron, copper, cobalt, manganese, zinc, and chromium are essential micronutrients, however, they become toxic at excessive levels [4].However, nonessential elements, such as mercury, lead, and cadmium are directly toxic to humans, animals, and plants.Levels of Pb, Ni Al, Cd, Fe, Hg, Zn, Mn, and Cr were detected in HWW [4][5][6].
Nuclear medicine uses gamma-emitting radioisotopes in hospitals for diagnosis (e.g.nuclear imaging) and treatment (e.g.radiopharmaceuticals).Radiopharmaceuticals (radioisotopes attached to a pharmaceutical), when ingested by the patients, are absorbed by a specific organ or diseased tissues, and then detected by a gamma camera [7,8].Radioisotopes that are used in medical applications include Be 7 , TC 99m , I 131 , I 123 , Cs 137 , Sm 153 , Rn 222, and Ra 226 are detected in HWW [9].Radiopharmaceuticals have been increasingly used in hospitals in recent years.During radioactive dose preparation and within a few hours after application, radioisotopes are released to hospital sewers from the patient's body via urination.Radiation discharge in the environment depends upon the type of radionuclide, the type of treatment, the metabolism of radiopharmaceuticals inside the body, and whether the treatment is in-patient or out-patient [10].Health problems such as cancer, birth defects, and sterilization can arise from radiation contamination.In addition, it can also sterilize the soil and contribute to water and air pollution [10].Other studies showed that wastewater treatment plants (WWTP) failed to completely remove I 131 and Tc 99m [11,12].
Pharmaceuticals have been frequently reported to be present in wastewater, surface water, and groundwater as they escape from wastewater treatment plants [13][14][15].German wastewater treatment plants contained over 30 different drugs, according to Ternes [13].In another study, in Brazil, Canada, and Germany, many drugs have been detected in surface and ground waters [16].Rodriguez-Mozaz et al. [17] analyzed antibiotics in treated effluent in wastewater treatment plants in seven European countries.They found that seventeen antibiotics were found in high concentrations in Ireland, Portugal, and Spain, while lower concentrations were found in Norway, Finland, Germany, and Cyprus [17].In Colombia, acetaminophen, diclofenac, azithromycin, ciprofloxacin, sulfamethoxazole, losartan, metoprolol, and omeprazole were present in all samples at concentrations from one up to some hundreds of g/L [18].In Nigeria, levels of drugs were found in the Odo Iya Alaro River water [19].A well-known adverse effect of drugs on living species is the feminization of male fish.Over the last several decades, genetic mutation and cancer have been associated with genotoxic substances released in HWW [20].HWW pollutants can develop antibiotic-resisting bacteria causing a biological imbalance in the aquatic ecosystem [1].HWW pollutants accumulated in soil due to the usage of contaminated sludge as fertilizer [21] and levels of pharmaceuticals were found in plants such as barley, cucumber, and lettuce [22].
In Oman, it is common to use STP-treated water and sewage generated for parks' irrigation, and as fertilizer for soil, respectively.In this study, HWW from the sewer system of SQUH, STP-treated water (TWW), and generated sewage sludge from STP, which receives HWW from SQUH, were analyzed for heavy metals, radioisotopes, and some pharmaceuticals.

Materials
Pure samples of metformin, atenolol, chlorpheniramine, triprolidine, diphenhydramine, and citalopram were provided by the National Pharmaceutical Industries Company (NPI), Al Rusayl, Muscat.The rest of the chemicals used, purchased from Sigma-Aldrich, were of HPLC grade.

Sample collection
HWW of SQUH and municipal wastewater from non-medical facilities at SQU were received in a sewage treatment plant (STP).Before being mixed with municipal water, HWW samples were collected from the two outlets of the sewer system of SQUH during working days and were mixed in equal volumes to produce representative samples.HWW samples were sealed immediately after collection and kept under ice during transport to the lab.Samples of TWW were collected from the STP outlet of treated water.Both HWW and TWW samples were filtered using a 0.45 m microfilter to remove suspended solids.The samples were stored in a freezer and defrosted to room temperature before conducting the analytical procedure.Five different batches of dry sewage sludge were collected at different times from STP at SQU. Sample collection of HWW, and TWW was carried out on Tuesdays every week in the period between 3 and 29 September 2016 making 4 representative samples.The sewage sludge samples were allowed to dry at 55 o C until constant weight was achieved.Dry sludge was kept in a desiccator to cool, then ground to powder and stored in well-closed polyethylene jars.Sewage sludge samples (5 representative samples) were collected on Tuesdays every week in the period between the 3 rd of September to the 3 rd of October 2016.

General characterization
The pH of HWW and TWW was analyzed using a calibrated pH meter.Chemical oxygen demand (COD) was analyzed using a multi-analyte photometer (Chemetrics, USA) using a COD kit after digestion in a digester block.Total dissolved solids (TDS) was measured using YSI professional plus apparatus (USA).Total suspended solids (TSS) were analyzed following a standard method using a microfilter of 0.45 m under vacuum [23].Biochemical oxygen demand (BOD5) was analyzed following a standard method [24].Total organic carbon (TOC), inorganic carbon (IC), and total carbon (TC) were analyzed using the GE Sievers InnovOx TOC analyzer (GE, USA).
The sludge pH was determined following a standard method [25].To measure the pH of sewage sludge, 1 g of dried sludge powder was mixed with 25 mL of CO2-free MLQ water and was left for 1 hour under constant stirring.The pH of the sludge slurry was determined using a calibrated pH meter.

Analysis of heavy metals and radionuclides
After collection, homogenizing, and filtration, portions from the representative samples of HWW or TWW were acidified to pH 2 using HNO3 to prevent bacterial growth and avoid possible adsorption metals on the container's walls.Metal concentrations were analyzed via inductively coupled plasma-mass spectrometry (ICP-MS), Aroura M90, Bruker, USA.For STP sludge, 5 g of the dried sludge was mixed with 50 mL (50 % HNO3).The mixture was heated at 80 o C to almost dryness and was allowed to cool at room temperature.The residual liquid was filtered through sintered Glass Gooch (G3) under vacuum and the residue was washed with MLQ water.Filtrate and washings were transferred to a volumetric flask.The volume was completed to the mark using MLQ water and metals were analyzed.
For the analysis of radioactivity, the acidified HWW or TWW was transferred to Marinelli beakers of 1 L capacity.The dry powder of sewage sludge was sieved through a 1000 mm sieve for particle homogeneity.Five hundred grams of the ground sludge was transferred to a Marinelli beaker (500 mL capacity).Both samples of HWW and sludge were sealed to prevent Rn 220 and Rn 222 from escaping in case they were emitted during analysis.The samples were left for 4 weeks so that equilibrium takes place between Ra 226 and its short progenies [26].The analysis was carried out using a calibrated high-purity germanium detector (HPGe) with background subtraction.

Drug recovery and matrix effect
For the drug recovery study, two standard mixtures (10 g/L and 100 g/L) of the six pharmaceuticals (metformin, atenolol, chlorpheniramine, triprolidine, diphenhydramine, and citalopram) were allowed to pass through a solid phase cartridge (Hypersep retain polymeric PEP cartridge, Thermo Scientific Company).Before the extraction process, the cartridge was conditioned by passing 5 mL methanol followed by 5 mL MLQ water through the cartridge.Mixtures of standards were allowed to pass through the cartridge at a rate of 1 mL/min.15 mL of absolute methanol was used as an eluent with an elution rate of 1 mL/min.Eluate was collected in a clean dry glass vial and was allowed to evaporate by a stream of nitrogen till dryness.The residue was dissolved in methanol (5 mL) and was immediately analyzed using LC-MS-MS (LCMS-8040, Shimadzu, Japan).The recovery was calculated via the comparison of the peak areas for analytes before and after the solid phase extraction process following Equation 1.
where, B and A are the peak areas of the standard solution before and after extraction, respectively [27].
To study the matrix effect (ME), the process involves the extraction of two sets of samples; one set contains the analyte in tap water (post-extraction sample), while the other set contains the analyte in a solvent (standard solution).Each set of samples was prepared using the same concentration of the analyte and was processed in the same way.Equation 2 can be used to calculate the level of enhancement or suppression caused by the matrix effect(s) [27].

Preconcentration of drugs from HWW, TWW, and Sewage sludge
After conditioning the Hypersep retain polymeric PEP cartridge with 5 mL methanol and 5 mL MLQ water, representative samples (200 mL) of HWW and TWW were allowed to pass through the cartridge following the same procedure mentioned above in the recovery study.For the analysis of pharmaceuticals in sewage sludge, a representative sample was made from the five powder sludge samples by mixing 5 g from each, and the samples were then homogenized.5 g of the homogenized sludge sample was mixed with 150 mL methanol in a round bottom flask.The organic materials were extracted in methanol using Soxhlet extraction for four hours.The solvent mixture was collected and allowed to almost dry using a rotary evaporator under vacuum.Residual methanol extract was collected in a glass vial and the round bottom flask was washed with a few millilitres of absolute methanol.Methanol extract and washings were mixed in the glass vial and the sample was dried with a nitrogen stream.The residue was dissolved in 5 mL methanol and the sample was filtered using a 0.45 m microfilter before analysis using LC-MS-MS.

Analysis of drugs using LC-MS-MS
The detection, identification, and quantification of the six pharmaceuticals were performed by a liquid chromatographic system coupled to a triple quadruple tandem mass spectrometer equipped with an electrospray ionization (ESI) source.The column that has been used in this project is Poroshell 120 EC -C18 column (3.0 ID × 100 mm length, 2.70 μm) from Agilent Technologies (PC18) and an oven set to 25°C.For gradient use, solvents A (0.1 % formic acid in water) and solvent B (100% acetonitrile) were used as the mobile phase.For best separation of the six drugs, the gradient program was set as follows: 2.5 min (5 % B); 2.5-5.50 min (29 % B); 5.50-9.50min (32 % B); 9.50-10.50min (32 % B); 10.50-10.60 min (32 % B); 10.50-13-50 min (5 % B) and 13.50-15 min (5 % B) to equilibrate for next injection (total run time was 15 min).The flow rate of the solvent was 0.30 mL/min with an injection volume of 5 μl.Desolvation line temperature, heat block temperature, and the cell temperature were set as 250°C, 400°C, and 40 °C, respectively, of positive mode.To optimize the conditions for analysis, 4.5 kV was used as the capillary voltage, 230 kPa as the collision-induced dissociation (CID) gas pressure, and 10 msec as the dwell time.The flow rate of the nebulizing and drying gases was 3 L/min.and 15 L/min., respectively.

Description of STP operation at SQU Campus
The wastewater effluents received from SQUH and non-medical areas at the university were allowed to pass through screening bars to remove large solid objects, followed by grit removal and fat skimming unit.The wastewater is transferred to a settling tank (primary clarifier) where coagulant(s)/flocculent(s) are added to facilitate the aggregation of small particles and their precipitation.The water is then transferred to an aeration/activated sludge tank, where biological degradation of dissolved organic material takes place, followed by settling in the secondary clarifier tank.The clear water is transferred to an activated carbon large column as a tertiary treatment and eventually, the water is subjected to disinfection using chlorine.The sludge from both the primary and secondary clarifiers is collected and left to dry in a drying bed.

General characterization of HWW, TWW, and sewage sludge
In general, water consumption in hospitals ranges between 200-1200 L/day [28].At SQUH, over 3 years between 2014-2017, the average water consumption is 890 L/day/bed, with an expected equal amount of HWW to be generated.General analysis was carried out 4 times for HWW and TWW.As presented in Table 1 the pH of all water samples tested lies within the pH range of natural water and the maximum allowed limits for water reuse in Oman [29,30].HWW contains much higher levels of TSS, COD, BOD, TOC, IC, TC, and turbidity than TWW.TSS in TWW is slightly higher than the maximum allowed levels for water reuse in Oman, Table 1 [29].COD values have tremendously decreased from 745 mg/L (before treatment) to 2.1 mg/L (after treatment) which is very low compared with the maximum allowed COD limit for water reuse in Oman.TDS did not show much variation in both HWW and TWW with both values falling within accepted limits for water reuse in Oman (Table 1).

Heavy metal analysis
HWW shows higher levels of metals than TWW for B, Al, P, Sr, Ni, Co, and Cd.However, the concentrations of Mg, Fe, Cu, and Zn in HWW show slightly higher levels than HWW for these elements, and this might be related to their presence in municipal wastewater that is mixed with HWW at STP. Co, Cd, and Ni in HWW, and Co and Ni in TWW appear slightly higher than the maximum allowed limits for water reuse (Table 2).Metal ions in HWW may chelate with organic moieties present in water even after treatment such as pharmaceuticals.Some pharmaceuticals acquire functional groups that are capable of chelation with heavy metals in water such as azo, carboxylic acid, amine, alcohol, amide, and phenolic groups [3,31].The sewage sludge generated from STP shows much higher levels of heavy metals than in HWW or TWW (Table 2).These metals are expected to be captured onto the sewage sludge via adsorption, ion exchange, and chelation [32].
The maximum allowed limits of heavy metals in soil in Oman were set only for Cu (1000 mg/Kg), Zn (3000 mg/Kg), Cd (20 mg/Kg), and Ni (300 mg/Kg) [29].As shown in Table 2, the levels of these four metals present in the sewage sludge are less than the maximum allowed limits in the soil for agricultural use in Oman.
Table 1.General characterization of HWW and TWW.* 4 water samples, A † Agricultural areas or water bodies with public access.B † †Areas with no public access, NA (Not applicable) [29].

Radionuclides analysis
Natural radiation provides about 88 % of the annual radiation dose to the population, however, medical procedures contribute most of the remaining 12 % [8].In this study, radionuclides that were found in both HWW and TWW include Cs 137 , K 40 , Ra 226 , Th 234 , I 131 , Ac 228 , Sb 125 , Tl 208 , Bi 124 , Zn 65, and Be 7 (Table 3) except for Cs 137 and Zn 65 , they were not detected in TWW.Radioactivity was found to be at higher levels in HWW than in TWW.The levels of radioactivity in sewage sludge are larger than HWW or TWW (Table 3).The radioactive ions are mostly adsorbed onto the sewage sludge during the treatment process.I 131 was not detected in any of the sludge samples, and this could be related to its volatilization during the drying process.Bq/kg) and I 131 (748-771.3Bq/kg) were found in sewage sludge from a wastewater treatment plant that received HWW.Gamma activities in the range of 24 -250 bq/Kg were found by Puhakainen [35] in sludge samples generated from a wastewater treatment plant in Finland and such radiation level was related to the use of medical applications and industrial processes.
Table 2. Analysis of heavy metals in HWW, TWW, and Sewage sludge.
(*4 samples analyzed from HWW and TWW.**5 samples of sewage sludge).NA (Not applicable) A † refers to agricultural areas or water bodies with public access.Vegetables or fruit can be eaten without boiling.B † refers to areas with no public access.
The concern about the environmental and health impact of radionuclides released in HWW is globally growing.In Sweden, the Swedish radiological authority conducted studies to monitor the levels of radioactivity released in HWW [36].Results show that a few of those radionuclides (P 32 , Y 90 , Tc 99m , In 111 , I 123 , I 131, and Tl 201 ) that were used in hospitals for radiotherapy and radio-diagnostics could be of potential risk.Sewage workers are exposed to Tc 99m , I 123 , I 131 , In 111, and Tl 201 while the public is exposed to I 131 in drinking water, and P 32 , Y 90 , In 111, and I 131 in fish consumption.The half-life time of radionuclides is the time required for half of the radioactive element to decay.However, the hazardous lifetime of a radioactive element is almost 10 to 20 half-lives, and it is the time required for a radioactive element to decay to about a thousandth or millionth of its original radiation.Thus, there is no actual safe level [37,38].Common medical radioactive waste includes Te 99m with a half-life of 6 hours while hazardous life of 2.5-5 days, Ga 67 with a half-life of 78 hours and hazardous life of 1-2 months, and I 131 with a half-life of 8 days and hazardous life of 80-160 days [37,38].Khan et al. [38] recommended that the radioactive waste is stored away for a minimum period of 10 half-lives when after decay only 0.1 % of the initial activity remains.The guidance levels recommended by WHO for the radioactivity in water are 10 bq/L for I 131 and Cs 137 , and 1 bq/L for Th 232 and Ra 226 [39].Based on these values, the radioactivity of I 131 and Cs 137 in HWW and TWW are less than the WHO limits, however, Th 232 and Ra 226 levels are higher in both HWW and TWW than these guidance levels.The STP treatment proved ineffective for the removal of the radionuclides from the wastewater showing ~31.6 % radioactivity removal from HWW.The radium equivalent activity [40] of the dry sewage sludge generated from the STP treatment plant was calculated using Eq.(3).Raeq (bq/kg) = ARa + 1.43 ATh + 0.077AK (Eq. 3) where ARa , ATh and AK are the specific activity concentrations of Ra 226 , Th 232 and K 40 in bq/kg, respectively.The radium equivalent activity for the different samples of sewage sludge was found to be 96.4 bq/kg which is lower than the upper permissible limit of Raeq in soil (370 bq/kg) [40].However, using contaminated radioactive sludge in agricultural soil can lead to the accumulation of radioactivity in the soil which can transfer to plants.In a recent study where wastewater from four hospitals were analyzed in Kuwait, the analysis showed all the wastewater from the four hospitals contained high levels of Tc 99m (0.14-14.151 bq/L), I 131 (13.56-27.1 bq/L), and low levels of K 40 (0.45-0.86 bq/L) [41].
The high RSD values of the analytical results of heavy metals, radioactivities, and other parameters of HWW, TWW, and sewage sludge are related to the variation in sampling and analysis.As mentioned earlier, the representative samples were collected every Tuesday in different weeks.Thus, HWW sample composition depends on the hospital activities and rate of water consumption.For TWW, the sample composition depends also on the varying activities in the hospital and the non-medical facilities on Campus.The variation in the values is not only related to the analysis but also due to sampling.This principle is emphasized in environmental analysis not only because of a varying environment [42] but also due to their low concentrations [43].Similar results of large standard deviation for environmental samples analysis were reported before for heavy metals in HWW [44] and other pollutants in groundwater [45].Table 3. Radioactivity in HWW, TWW, and Sewage sludge.

Pharmaceutical Analysis
Based on the method developed, as mentioned earlier, the drugs showed good separation in the chromatogram (Figure 1) with the chromatographic parameters, LOD, and LOQ presented in Table 4.All the recovery percentages were higher than 80.5 % except for metformin which shows a low percentage of recovery in both concentrations of drug mixtures (15.08 % for 10 g/L and 9.81% for 100 g/L, Table 5).All the recovery percentages were higher than 80.5 % except for metformin which shows a low percentage of recovery in both concentrations of drug mixtures (15.08 % for 10 g/L and 9.81% for 100 g/L, Table 5).The low recovery of metformin is due to its polar nature.Thus, metformin is not fully retained by the solid phase and an extent of the compound elutes with water providing less loading.The other five compounds show good recovery as they are less polar or non-polar compared to metformin.To study the matrix effect of the target compounds, two samples of tap water were injected into the LC-MS-MS.The first sample is tap water without drug spiking.The second sample is tap water spiked with a mixture of 6 drugs at two concentrations (10, 100 g/L).Tap water was taken in this study as a pure or blank sample.The chromatogram of non-spiked tap water shows no peaks during the run.The percentage of matrix effect falls between 88.70 and 99.9864 (Table 5) indicating less effect of the matrix on compound ionization.Representative samples of HWW, TWW, and sewage sludge were analyzed 3 times for the pharmaceuticals under investigation using the developed method.Average and standard deviation values were calculated, Table 6.Diphenhydramine and chlorpheniramine are found in all samples with different concentrations following the order: Sludge >> HWW > TWW.The large contents of both drugs present in the sewage sludge are related to their adsorption onto the sludge surface.Chlorpheniramine in sewage sludge was found to be higher by 3.25 folds than HWW, while diphenhydramine was higher in sludge by 61.5 folds than HWW.Citalopram was found only in the sludge sample with an average of 168.15 g/kg, however, atenolol was found only in HWW with an average of 0.0264 g/L.The unavailability of metformin in the samples tested could be related to its very low recovery on the solid phase and it will be tested soon in another study.TWW shows less concentration of drugs than HWW and this can be related to their adsorption onto the sludge and also to the dilution by mixing municipal water with HWW at STP. Radjenović et.al [46] found that the most abundant pharmaceutical in sewage water was acetaminophen (7.1-11.4μg/L), ibuprofen (14.6-31.3μg/L), gemfibrozil (2.0-5.9 μg/L), ofloxacin (0.89-31.7 μg/L), atenolol (0.84-2.8 μg/L, bezafibrate (1.9-29.8μg/L), hydrochlorothiazide (2.3-4.8 μg/L) and glibenclamide (0.12-15.9 μg/L).In a recent study, levels of antibiotics were found in effluents from wastewater treatment plants in some European countries.For example, ciprofloxacin was found to be 231.4 [46].Other Studies have shown that pharmaceuticals that are more commonly found in the environment include sulfonamides (0.02-0.58 µg/L), ciprofloxacin (6-60 µg/L), acetaminophen (10-23.33µg/L), diclofenac (0.01-510 µg/L), naproxen (0.5-7.84 µg/L), ibuprofen (0.49-990 µg/L), ketoprofen (0.13-3 µg/L), propranolol (0.05 µg/L) and clofibric acid (0.47-170 µg/L) in addition to others [47,48].According to Peng et al. [49], the maximum concentrations of ibuprofen and clofibric acid in water samples from the Pearl River Delta were 1.42 and 0.248 µg/L, respectively.In a study of hospital wastewater in Kuwait, a high concentration of paracetamol (580 μg/L) was found [41].The analysis in this paper targeted the above-mentioned six drugs.However, other drugs could be available in HWW, TWW and Sewage sludge will be investigated in the future.and Be 7 ), however in less concentrations and radioactivity, respectively, than HWW.The low level of radioactivity and pharmaceuticals in TWW can be related to their adsorption on the sewage sludge, the dilution factor as HWW is mixed with other municipal water in STP, and probably an extent of degradation for the pharmaceuticals in the treatment process.Due to the presence of some persistent substances, such as pharmaceuticals, in HWW and TWW, there is an expected error in BOD values.This is because these persisting substances could sicken the bacteria, and this can affect the level of dissolved oxygen consumption.STP sewage sludge accumulates larger concentrations of pharmaceuticals (chlorpheniramine, diphenhydramine, and Citalopram), more radioactivity (Cs 137 , K 40 , Ra 226 , Th 234 , Ac 228 , Sb 125, and Be 7 ), and higher levels of heavy metals than HWW.For example, diphenhydramine, K 40, and Cd are 61.5 folds, 33.4 folds, and 211 folds higher in STP sludge than in HWW.
The sewage sludge generated from STP, which receives HWW, is considered toxic and must not be used as a fertilizer for agricultural lands unless treated.Treated wastewater is still contaminated by pharmaceuticals, radionuclides, and heavy metals.Therefore, the study recommends a primary stage of physicochemical treatment for HWW before its mixing with municipal wastewater for further treatment.Figure 2 represents the evaluation of STP treatment of hospital wastewater as most of the pollutants move from treated water to sewage sludge.Currently, the STP at SQU is closed and HWW is directed to a membrane bioreactor technology unit for wastewater treatment which will be evaluated in the future.
HWW should be considered as hazardous wastewater and effective legislation for its treatment and control is required.

Conclusions
Hospital wastewater, in this study, contains heavy metals, radioisotopes, and pharmaceuticals.Heavy metals did not show much variation between HWW and TWW because of their presence in non-medical wastewater from the residential area at the university campus.The radionuclides; Cs 137 , K 40 , Ra 226 , Th 234 , I 131 , Tl 208 , Zn 65 Ac 228 , Sb 125 , Bi 124 and Be 7 were found in HWW, but Cs 137 and Zn 65 were not found in TWW.However, in sewage sludge, all radionuclides were present except I 131 .Some pharmaceuticals were found to escape the STP treatment and were found in TWW.Pharmaceuticals, heavy metals, and radionuclides were found in larger concentrations in the sewage sludge than in HWW or TWW.The study emphasizes their escape from the STP treatment posing danger to public health and the environment.Thus, a physicochemical process is needed to treat HWW before being mixed with municipal wastewater for further treatment.Contaminated sewage sludge should not be used in agriculture as fertilizer unless clarified from HWW contaminants.

Figure 2 .
Figure 2. Evaluation of hospital wastewater treatment in a sewage treatment plant (STP).
[33]aña et al.[33]detected radioactivity in influents, effluents, and sewage sludge generated from wastewater treatment plants in Spain.Sewage sludge was found to contain high levels of K 40 and Be 7 but less amounts of I 131 .Jiménez et al.

Table 4 .
The chromatographic parameters, LOD, and LOQ for the analysis of pharmaceuticals.

Table 5 .
Recovery data and matrix effect at 10 g/L and 100 g/L.