Medical Wastewater Research Articles

Anthropogenic Rare Earth Elements: Gadolinium in a Small Catchment in Guizhou Province, Southwest China.

Rare earth elements (REEs), known as “industrial vitamins”, are widely used in medical treatment, industry, agriculture, etc. However, with the increasing demand for REEs, excess REEs, such as gadolinium (Gd), are considered micropollutants in the environment. In this paper, the distributions of dissolved REEs were analyzed in three small streams, in order to determine the extent and occurrence of Gd anomalies. The shale-normalized REE patterns in the three streams were less smooth with heavy REEs higher than light REEs, for a weak reaction of the heavy REE complexes. A negative Ce (cerium) anomaly and positive samarium (Sm) and europium (Eu) anomalies were observed in the three streams and the negative Ce anomaly was affected by the pH of the alkaline rivers. However, a positive Gd anomaly was found in only a typical urban small stream, Jinzhong. With a population of approximately 60,000, Jinzhong runs by a hospital and through wastewater treatment plants (WWTPs). The concentrations of Gd in Jinzhong ranged from 1.54 to 86.65 ng/L with high anthropogenic Gd proportions (63.64%–98.07%). Anthropogenic Gd showed significant seasonal variations and distinct spatial disparities from upstream to downstream, and it was associated with certain ions such as Cl−. Anthropogenic Gd could be attributed to gadopentetic acid (Gd-DTPA), which is used in magnetic resonance imaging (MRI) in hospitals. This type of Gd was shown to be correlated with municipal wastewater. Due to the high stability and low particulate reactivity in water, anthropogenic Gd has great potential to serve as a tracer to prove the presence of medical wastewater.

Adsorption of low concentrations of bromide ions from water by cellulose-based beads modified with TEMPO-mediated oxidation and Fe(III) complexation

Due to strong activity, it is very difficult to remove low concentrations of bromide in medical wastewater by traditional method, thus highly effective and greener adsorbents should be utilized to design. In this work, the cellulose beads (CBs) were modified by the TEMPO-mediated oxidation and then bonded with Fe3+ to fabricate Fe(III)-complexed carboxylated cellulose beads (Fe-CCBs) adsorbents. Structure and properties of Fe-CCBs were analyzed using Energy dispersive spectrum (EDS), Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), total acidity and basicity groups, X-ray diffraction (XRD), N2 adsorption-desorption and Thermogravimetric (TGA). Moreover, batch adsorption experiments showed that the adsorption of Br− was better consistent with general-order kinetic model and Liu isotherm model, which could also further clarify the adsorption process mechanism. Meanwhile, the results revealed that removal of Br- was a spontaneous exothermic process and was more suitable to be carried out under neutral or acidic conditions. Furthermore, the mechanism of adsorption behavior of bromide ions on Fe-CCBs was based on a combination of electrostatic attraction and outer-sphere complexation. The results of this study can provide guidance for the design of novel material adsorbents and the removal of harmful anions from aqueous solutions.

Validation of ultrasonic-assisted switchable solvent liquid phase microextraction for trace determination of hormones and organochlorine pesticides by GC–MS and combination with QuEChERS

QuEChERS and switchable solvent liquid phase microextraction (SS-LPME) were respectively used as pretreatment and preconcentration tools to allow trace determination of selected organochlorine pesticides and hormones by gas chromatography mass spectrometry (GC–MS). The effects of principal SS-LPME variables and their interactions were evaluated with a Box-Behnken experimental design. The limits of detection obtained by direct GC–MS determination were enhanced by about 33–115 folds under the optimized SS-LPME conditions. The SS-LPME method was applied to tap water, well water, lake water, medical wastewater and tea samples. Satisfactory recovery results were obtained for all but the tea samples using the conventional calibration plot. Matrix matched calibration standards were used to improve the percent recovery of analytes to almost 100% in the tea samples. The combined QuEChERS and SS-LPME method was applied to tomato samples and matrix matching was also used to significantly improve analyte recoveries.

The enhanced visible-light-driven antibacterial performances of PTCDI-PANI(Fe(III)-doped) heterostructure

The development of visible-light-responsive photocatalysts with organic semiconductors is considered as an important and promising way to solve the energy crisis and environmental pollution. In this work, PTCDI and PTCDI-PANI(Fe(III)-doped) heterostructure were prepared through radical polymerization and modified amidation reaction. They could be used as visible-light-driven photocatalysts for the treatment of medical wastewater containing Staphylococcus aureus and E. coli bacteria. The as-prepared PTCDI-PANI(Fe(III)-doped) exhibited comparably higher photocatalytic activity beyond PTCDI. Under the irradiation of visible light, the PTCDI-PANI(Fe(III)-doped) showed optimized sterilization efficiencies towards E. coli and Staphylococcus aureus bacteria, which was 95.8% and 99.3%, respectively. The enhanced photo-induced antibacterial effect by PANI(Fe(III)-doped)-grafting was mainly attributed to: (1) PANI has a narrow band gap of 2.8 eV; (2) The relatively higher conduction band position (-2.1 eV) of PANI promotes the reaction of O2+e－⟶·OH; (3) The strengthened junctions of amide bond between PTCDI and PANI improve the separation efficiency of photogenerated electron-hole pairs; (4) The relatively rougher surface of PTCDI-PANI comparing with PTCDI improves the bio-surface interactions or bacterial adhesion; (5) Fe(III)-doping acts as a conducting tunnel and promotes the charge transfer between PANI and PTCDI.

Degradation of naphthalene with magnetic bio-char activate hydrogen peroxide: Synergism of bio-char and Fe–Mn binary oxides

This study investigated the hydrogen peroxide (H2O2) activation potential of Fe–Mn binary oxides modified bio-char (FeMn/bio-char) for the degradation of naphthalene, the dominant PAHs in drinking water. Results showed that FeMn/bio-char exhibited 80.7- and 2.18-times decomposition rates towards H2O2 than that of pure bio-char and Fe–Mn binary oxides, respectively, and consequently the FeMn/bio-char/H2O2 photo-Fenton system presented highest naphthalene removal efficiency. The enhanced catalytic activity could be ascribed to the synergistic effect of the combination of bio-char and Fe–Mn binary oxides, such as promoting the adsorption capacity towards contaminant, increasing concentration of persistent free radicals (PFRs) and introducing Fe–Mn binary oxides as new activator. According to the batch-scale experiments, FeMn/bio-char/H2O2 photo-Fenton system could degrade naphthalene effectively at a wide pH ranges, and 82.2% of naphthalene was degraded under natural pH of 5.6 within 148 min. Free radicals quenching studies and electron spin resonance (ESR) analyses verified that the dominant free radical within FeMn/bio-char/H2O2 photo-Fenton system was hydroxyl radical (•OH). According to the preliminary analysis, the generation of •OH were ascribed to the activation of H2O2 by Fe (II), Mn (II) and PFRs on the catalyst surface. The mainly degradation intermediates of naphthalene were identified by GC-MS analysis. Consequently, the possible degradation pathways were proposed. Moreover, naphthalene degradation experiments were also conducted in river, tap water, industrial wastewater as well as medical wastewater, and the results indicated that the FeMn/bio-char/H2O2 photo-Fenton system was effective in the treatment of naphthalene in natural waters. This study brings a valuable insight for the potential environmental applications of modified bio-char.

Preparation and properties of visible light responsive RGO/In2TiO5 nanobelts for photocatalytic degradation of organic pollutants

Electrospinning and solvothermal methods were used to synthesize RGO/In2TiO5 nanobelts. The prepared samples were characterized with XRD, SEM, UV–vis DRS, N2 adsorption-desorption isotherms, FT-IR and Raman spectroscopy. The results have shown that the samples presented an orthorhombic structure without any secondary phase, and the morphology was not noticeably changed after coupling RGO. The RGO (1 wt%)/In2TiO5 nanobelts showed the highest photocatalytic activity. After 120 min of simulated sunlight irradiation, the degradation rate of RhB was up to 97.5%. Meanwhile, RGO/In2TiO5 nanobelts showed excellent photocatalytic degradation property for fluoroquinolone antibiotic levofloxacin (LEV). The increased electrons and holes separation, enhanced active sites and improved light acquisition were the reasons for the outstanding photocatalytic performances of the photocatalyst. Moreover, terephthalic acid photoluminescence (TA-PL) experiments confirmed that the hydroxyl radicals (OH) were generated during the photocatalysis processes. The enhanced photocatalytic activity allows RGO/In2TiO5 nanobelts to be a promising candidate to treat antibiotic medical wastewater field in the future.

Accurate and Sensitive Determination Method for Procymidone and Chlorflurenol in Municipal Wastewater, Medical Wastewater and Irrigation Canal Water by GC-MS After Vortex Assisted Switchable Solvent Liquid Phase Microextraction.

In this study, the detection power of a gas chromatography mass spectrometer (GC-MS) for procymidone and chlorflurenol was significantly enhanced using switchable solvent liquid phase microextraction (SS-LPME) as a preconcentration tool. This was achieved by a comprehensive optimization of significant parameters to the SS-LPME method such as switchable solvent amount, concentration and amount of sodium hydroxide, pH effect and mixing effect. The optimum experimental conditions obtained were used to determine analytical figures of merit for the analytes. The limits of detection obtained were 0.44 and 2.9ng/mL for procymidone and chlorflurenol, respectively. The optimum method was applied to water sampled from an irrigation canal and two wastewater samples. The samples were spiked at two concentrations and the percent recovery results obtained ranged between 86 and 115% for both analytes. The recovery results together with the low standard deviations recorded validated the method as accurate and precise.

Integration of Membrane Bioreactor and Nanofiltration for the Treatment Process of Real Hospital Wastewater in Ho Chi Minh City, Vietnam

Hospital wastewater contains pharmaceutical residues, chemicals, and pathogens that cause coloration and nourish pathogenic microorganisms. The objective of the study was to evaluate the effectiveness of a medical wastewater treatment system at Military Hospital 175 (Ho Chi Minh City, Vietnam) that combined a membrane bioreactor (MBR) system with nanofiltration (NF). The influent of the system was the wastewater discharged from the operating rooms of the hospital. The system has a capacity of 50 L/day and operates at three organic load rates (OLR) of 0.5, 1.5 and 2.5 kgCOD/m3day (COD: Chemical oxygen demand), in which each load rate operates for 40 days. The results showed that most nutritional criteria generally achieved positive results. Specifically, the average COD removal was shown to be consistently high throughout the three phases at 94%, 93.3%, and 92.7%, respectively. For removal of nitrogen, the system demonstrated efficiencies of 75%, 79%, and 83%, respectively, to three phases. The log removal value (LRV) for Escherichia coli and coliform bacteria were higher than four throughout the study period. The average removal efficiency for color and total iron was approximately 98% and 99%, respectively. The water quality after treatment, especially after NF, meets the Vietnamese standard of grade A. The arrangement in which the MBR preceded NF was also found to limit the amount of soil and solids entering subsequent treatment, which therefore improved the efficiency of NF, as demonstrated by the stability of post-NF transmembrane pressures throughout three cycles renewed by two backwashes.

Highly efficient removal of diclofenac sodium from medical wastewater by Mg/Al layered double hydroxide-poly(m-phenylenediamine) composite

The emerging pollutant non-steroidal diclofenac sodium (DCF) has aroused increasing concerns, and the efficient removal of DCF from wastewater is becoming an urgent problem. In this study, the Mg/Al layered double hydroxide-Poly(m-Phenylenediamine) (LDH-PmPD) composite was synthesized, characterized and used for DCF adsorptive removal. The adsorption kinetics, isotherms as well as various influence factors, e.g., pH, humic acid, ions species and strength on the DCF removal were systematically investigated. The results showed that the presence of LDH weakened the accumulating density of PmPD and increased the specific surface area, which favored DCF adsorption on LDH-PmPD surface. LDH-PmPD exhibited a maximum adsorption capacity of 588 mg/g, which was superior to those of the conventional adsorbents. The artificial aging (100 d) experiment indicates a good stability of LDH-PmPD. Furthermore, due to the presence of electrostatic attraction, π-π electron-donor-acceptor interaction and N···HO hydrogen bonding between DCF and LDH-PmPD, the adsorption process was very effective in medical wastewater. The DCF removal efficiency reached nearly 100% within only 2 min in real medical wastewater using 0.125 g/L adsorbent. All these suggested that the prepared LDH-PmPD has great potential for DCF-contaminated water treatment.

Nghiên cứu xử lý nước thải y tế bằng phản ứng Fenton/ozone kết hợp lọc sinh học hiếu khí

The study was aimed to treat medical wastewater reach the national discharge standard. In this study, the medical wastewater first treated by the Fenton/ozone reactor, then continuously treated by the submerged aerated fixed bed bioreactor (SAFB); reactors were tested at the lab-scale conditions. The treatment efficiency of medical wastewater by the Fenton/ozone reactor was rather high but the organic residues from wastewater could not meet the discharge standard of QCVN 28:2010/BTNMT (A column). By continuously treated wastewater by the SAFB with the hydraulic retention time of 2 hours, the average loading rate of 0.723 kg BOD5/m3.day, the treatment efficiencies of COD, BOD5, P-PO43- were 56.1%, 65.5%, and 55.0%, respectively. After treated by Fenton/ozone process combined to SAFB reactor, medical wastewater met the discharge standard of the QCVN 28:2010/BTNMT (A column).

WHEN LCA APPLIES TO HEALTH SERVICE INDUSTRY

The health service industry involves activities that provide medical services (hospital), manufacture of medical equipment or drugs, and medical insurance services. Options of research methods to measure the impact of services on environmental aspects are available. One among which is life cycle analysis (LCA), the recently popular practice in Indonesia. This paper attempts to explore whether LCA could be fitted to the health service industry. A literature review would help in procuring related references from various publications accompanied by several research results and related studies. For describing the application of LCA in hospitals, several articles were collected, which were later arranged according to certain systematics from several sources. The LCA methodology used here consists of the following four stages: goal and scope definition, life cycle inventory analysis, impact assessment, and interpretation. The stages follow the International Organization for Standardization (ISO) 14040 and UNEP SETAC, 2011. Several studies using the LCA method in hospitals have reported specific profiles such as the management of biohazardous medical waste (BMW) and waste water. Several studies have also used LCA methods to assess specifically the environmental and health impacts of a specific component of the hospital or hospital activities. For example, studies have assessed the impact of equipment used in the form of containers, catheter, laryngeal mask, gowns and also infrastructures’ facilities. The results of this study confirmed that the LCA method is suitable in health service industry, particularly in hospitals. Considering the merits and drawbacks involved in applying this method, one could further apply it to related health service issues.

Medical Wastewater Characterization in the Gaza Strip: Al-Shifa Medical Complex as a Case Study

: Al-Shifa medical complex is one of the most famous medical complex in the Gaza Strip. Since 1946 it was expanded many times, nowadays, the total clinical capacity has 564 beds on an area of 42,000 m2. The main aim of the current research is to characterize the medical wastewater in the Gaza Strip. Currently, wastewater from hospitals is discharged to the public network then to overloaded central wastewater treatment plants, where partially treated effluent is infiltrate to the groundwater and the majority discharged to the sea. Composite samples from different sectors of the complex are collected every two hours for 24 hours and analyzed for physical and chemical characteristics. The pH from different medical sectors showed an acceptable range for disposal to the public network, while the salinity was extremely high and differs from sector to another. The Surgery department recorded the highest wastewater pollution i.e. TSS, BOD, and COD accounted for 3008, 1150, and 5350 mg/L, respectively, while the highest TKN (117 mg/L) was from the surgery operation room. Heavy metals such as Cd, Zn, and Pb in the medical wastewater from Al-Shifa medical complex do not constitute a threat to public wastewater sewerage system, mostly below the detection limits. It is highly recommended to further investigate the causes of strong pollution from both the surgery department and surgery room to propose pretreatment before disposal to the public network. Microbiology and infectious diseases and radioactive pollution should be considered in future planned research to gain comprehensive medical waste characteristics in the Gaza Strip.

Facile one pot green synthesis of Chitosan-Iron oxide (CS-Fe2O3) nanocomposite: Removal of Pb(II) and Cd(II) from synthetic and industrial wastewater

Abstract A novel Chitosan-Iron oxide (CS-Fe2O3) nanocomposite was synthesized by a facile one pot green route. The surface morphology of nanocomposite was characterized by various instrumental techniques such as SEM/EDX, TEM, AFM, XRD, FTIR, TGA and BET analysis. The nanocomposite was further explored for the sequestration of toxic metals Pb (II), Cd (II) in single system and Pb (II) in binary system from aqueous solution. The influence of various sorption parameters such as initial concentration, contact time, pH and temperature were evaluated to get the optimum conditions. Langmuir and Freundlich isotherm were applied to fit the experimental data. Pseudo-first, Pseudo-second order and intra-particle diffusion models were applied for the kinetic study. The Langmuir isotherm and Pseudo-second order kinetic model were best fitted with experimental results. The sorption process was found to be endothermic, spontaneous with increased randomness as confirmed by thermodynamic studies. The nanocomposite showed excellent recyclable efficiency upto five cycles. The nanocomposite has also been proved to be an excellent potential sorbent for the removal of potentially toxic elements from industrial and medical wastewater. Therefore, the present nanocomposite is considered as an efficient and ecofriendly sorbent for the removal of potentially toxic elements from wastewater.

Novel mesoporous Fe3O4/SiO2/CTAB–SiO2 as an effective adsorbent for the removal of amoxicillin and tetracycline from water

The current study was carried out to investigate the efficiency of using magnetic mesoporous of cetyltrimethylammonium bromide-functionalized silica-coated magnetite for removing amoxicillin (AMX) and tetracycline (TC) from tap water, river water, and medical wastewater as real samples. The properties of the synthesized adsorbent were characterized through transmission electron microscopy (TEM), scanning electron microscopy, X-ray diffraction spectrometry, Fourier transform infrared spectroscopy, vibrating sample magnetometry, pHpzc, and also Brunauer, Emmett, and Teller (BET) methods. The BET surface area and the average diameter of mesoporous Fe3O4/SiO2/CTAB–SiO2 in accordance with TEM were 157.8 m2 g−1 and around 55 nm, respectively. In batch tests, the adsorption parameters, including the initial concentration, contact time, pH of solution, ionic strength, and adsorbent dose, were analysed. The experimental adsorption data were modelled using different classical and recently developed models. According to the results, the maximum adsorption capacities of AMX and TC on mesoporous Fe3O4/SiO2/CTAB–SiO2 were found to be 362.66 and 220.70 mg g−1, respectively. Also, the results indicated that AMX and TC loaded on the adsorbent could be easily desorbed with 0.1 mol L−1 HNO3+ acetonitrile (1:1, v/v) and the adsorbent showed good reusability for the adsorption of the drugs studied.

REDISAIN INSTALASI PENGOLAHAN AIR LIMBAH (IPAL) RUMAH SAKIT UMUM DAERAH (RSUD) TIMIKA, PAPUA

Hospital is playing an important role in serving people who need to get health. On the other hand its occurrence causes some problems as well. One of them is the infectious wastewaters which are potential to cause a dangerous effect for human life. A lot of hospitals in Indonesia do not have the proper wastewater treatment plant yet. The local hospital of County Timika has already had a wastewater treatment plant (WWTP), but until now the capacity of the unit can not fulfil the required level of environmental standard yet. One of the problems is the technically improper treatment processes. To solve the problems, the WWTP must be redesigned and modifief by using a combination technique of anaerobik and aerobic biofilter treatment processes.The newly proposed design process of WWTP for the local hospital in TImika has already prepared to be applied. Keywords : Medical Wastewater Treatment Process, anerobic/aerobic biofilter

Investigation of the Potential Association between Clustered Regularly Interspersed Short Palindromic Repeats (CRISPR) and Antibiotic Resistance Pattern of Bacterial Strains Isolated from Medical Waste and Environmental Water

Enterobacteriaceae are important human pathogens that cause many food and waterborne illness. Rapid emergence of multi-drug resistant bacteria in Bangladesh has become a serious problem. Phage-host interaction is now considered as the major driving force for the conversion of non-pathogenic bacteria to pathogenic ones. Evolution of highly pathogenic and antibiotic resistant bacteria largely depends upon the horizontal gene transfer by means of plasmid, megaplasmid and bacteriophages. Conversely, bacteria may acquire a novel defence mechanism called CRISPR (Clustered regularly interspersed short palindromic repeats) that can restrict horizontal transfer of plasmids and bacteriophages to limit the spread of antibiotic resistance genes among bacterial species. In this study, twenty bacterial strains were isolated from water of different medical waste and Buriganga river. Therefore, CRISPR locus was investigated following various biochemical and molecular analysis of those bacterial isolates. Identification of the bacterial isolates was conducted by Polymerase Chain Reaction (PCR) based assay of 16S rDNA extracted from those isolated strains. Results indicated that most strains were identified as Proteus mirabilis and Citrobacter freundii which mainly cause septicemia, and pneumonia in human. Thereafter, antibiogram of these strains was performed by using 11 different antibiotic discs where bacterial isolates from medical drainage system showed more resistant to antibiotics than the river water. In this study, CRISPR locus was also investigated within the genome of the isolated bacterial stains but unexpectedly, we did not find any CRISPR locus in their genome. In conclusion, we confirm that multi-drug resistant bacterial strains are devoid of CRISPR locus suggesting a possible negative association between CRISPR locus and antibiotic resistance. Further studies to pinpoint are required to elucidate the underlying mechanism of the association between CRISPR and antibiotic resistance in these isolated strains.

Synthesis of Guar gum/bentonite a novel bionanocomposite: Isotherms, kinetics and thermodynamic studies for the removal of Pb (II) and crystal violet dye

In the present study, the performance of Guar gum/bentonite bionanocomposite was evaluated for the sequestration of Pb (II) and crystal violet (CV) dye from aqueous solution. The bionanocomposite was characterized by SEM, EDX, FT-IR, XRD, TGA, BET and TEM techniques. The bionanocomposite showed porous, crystalline nature with particle size ranging between 3 and 11nm and increased thermal stability. The point of zero charge was found to be 2.2. The maximum adsorption was observed at pH5.1, 7.6 and contact time 240min, 300min for Pb (II) and CV, respectively. The kinetic study revealed that the adsorption process of Pb (II) and CV onto the bionanocomposite followed the pseudo-second order model, confirming chemisorption as a rate determining step. The adsorption isotherm was in good agreement with the Freundlich for Pb (II) and Langmuir for CV isotherm model, respectively. Thermodynamic studies showed that the process was physiosorption, spontaneous and endothermic with increased in randomness. The desorption study of Pb (II) and CV exhibited the excellent regenerative efficacy (upto fifth cycle) of bionanocomposite using 0.1M HCl. The bionanocomposite has also been successfully applied for the removal of heavy metals from electroplating, battery manufacturing and medical wastewater before and after spiking CV dye solution to it.

Simultaneous Combination of Electrocoagulation and Chemical Coagulation Methods for Medical Wastewater Treatment

Chemical coagulation, electrocoagulation, and combined electrocoagulation-chemical coagulation methods were used to reduce organic compound concentrations in medical wastewater. Some parameters in the methods were adjusted to optimize the process, including the applied current, distance between electrodes, number of electrodes, acid levels, coagulant type, and contact time. Chemical Oxygen Demand (COD) was used to indicate the total amount of organic compounds in the system. The results showed that the following conditions can be applied to achieve optimum results: 3 A of applied current, 4 pairs of electrodes, with 1 cm of distance between each electrode pair, a pH of 8, 1 g of polyaluminum chloride as the coagulant, and 3 hours of contact time. The optimum removal efficiency levels of total organic compound achieved via chemical coagulation, electrocoagulation, and the simultaneous combination of electrocoagulation-chemical coagulation methods were 41%, 62.51%, and 92.21%, respectively.

Synthesis and application of TiO2/SiO2/Fe3O4 nanoparticles as novel adsorbent for removal of Cd(II), Hg(II) and Ni(II) ions from water samples

In the current study, SiO2/Fe3O4 core–shell nanoparticles functionalized with TiO2, using a simple method and application for removal of Cd(II), Hg(II) and Ni(II) ions from aqueous solution. The structure of the resulting product was confirmed by X-ray diffraction spectrometry, transmission electron microscopy (TEM), pHpzc and Brunauer, Emmett and Teller methods. The average diameter of TiO2/SiO2/Fe3O4 nanoparticles according to TEM was obtained around 48 nm. In batch tests, the effects of pH, initial metal concentration, contact time and temperature were studied. Adsorption of metal ions was studied from both kinetics and equilibrium point of view. Maximum adsorption capacity of Cd(II), Hg(II) and Ni(II) on TiO2/SiO2/Fe3O4 nanoparticles was 670.9, 745.6 and 563.0 mg g−1, respectively. Adsorption–desorption results showed that the reusability of nanoparticles was encouraging. This adsorbent was successfully applied to removal Cd(II), Hg(II) and Ni(II) ions in real samples including tap water, electronic wastewater and medical wastewater.

REMOVAL OF ORGANIC MATTER IN WASTEWATERS OF A MILK FACTORY AND A HOSPITAL USING A CUBIC LATTICE BASED ROTATING BIOLOGICAL CONTACTOR IN VIETNAM

Pilot tests of a cubic-lattice-based rotating biological contactor were implemented to remove organic matter from wastewater from a milk factory and a hospital in Vietnam. In the milk factory wastewater, the biochemical oxygen demand (BOD) removal ratio was stable between 60% and 90% (average 75%) using this method, with a BOD surface load of 0.002–0.020 kg•m−2•day−1. The average nutrient ratio of the raw wastewater was 0.13 of total nitrogen and 0.015 of total phosphorus compared with 1.0 of BOD. The BOD of treated water was less than 50 mg•L−1, achieving category B of the industrial wastewater standard of Vietnam (QCVN 40:2011). For the hospital wastewater, the BOD removal ratio was stable between 60% and 90% (average 78%), with a BOD surface load of 0.005–0.022 kg•m−2•day−1. The average nutrient ratio of the raw wastewater was 0.25 of total nitrogen and 0.018 of total phosphorus compared with 1.0 of BOD. The BOD of treated water was less than 50 mg•L−1, satisfying category B of the medical wastewater standard of Vietnam (QCVN 28:2010/BTNMT). The electric power consumption was 0.73 KWh•m-3 of wastewater. The sludge conversion ratio from BOD was 0.51 kg TSS•kg BOD−1 based on the excess sludge and suspended solids in raw wastewater and treated water.