Hospitals are primary sources of contaminants followed from the diagnostic, laboratory, and research activities as well as medicine excretion by patients, which include active component of drugs and metabolite, chemicals, residues of pharmaceuticals, radioactive markers, iodinated contrast media, etc. [1] [2]. Further, it is evaluated that 75% of the wastes generated by hospitals are general health care wastes, while the remaining 25% are regarded as hazardous infectious waste [1]. Incorrect disposal of infectious hospital wastes and wastewater can provoke grave hazards to public health and nature [3] [4] [5].

An unknown case of pneumonia was first reported in Hubei, China [6]. By January 7^th, 2020, Chinese scientists had isolated a Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) from patients in Wuhan [7]. Following the severe acute respiratory syndrome coronavirus (SARS-CoV-1) outbreak in 2002 and the Middle East respiratory syndrome coronavirus (MERS-CoV) outbreak in 2012, SARS-CoV-2 is the third coronavirus to surface during these two decades, which has put global public health institutions on high alert [8] [9]. The transmission routes of SARS-CoV-2 comprise droplet transmission and contact transmission; airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed [1].

The drainage of hospital wastewaters mostly those without suitable treatment could reveal the public in danger of infection. Indeed, below the COVID-19 pandemic context in the globe, it is vital to decrease the health dangers to the public and nature. Therefore, it is obligatory to suitably disinfect the hospital wastewater prior to being transported or discharged. Methodical researches regarding the disinfection of hospital wastewaters, particularly distinct disinfection propositions throughout the COVID-19 pandemic, stay scarce until now [1]. Consequently, this work focuses on disinfection techniques for the treatment of hospital wastewater and discusses propositions for hospital wastewater disinfection during the COVID-19 pandemic in the world.

Disinfection techniques using ozone, ultraviolet (UV) light, liquid chlorine, chlorine dioxide, and sodium hypochlorite are usually applied for killing pathogens in hospital wastewater [10] [11] [12]. Figure 1 illustrates the wastewater disinfection strategy in the hospital [1]. A disinfection technique possesses distinctive interests and drawbacks (Table 1). Employing a particular kind of disinfection technology has to be decided through taking into account simultaneously economic and feasible details, like the quantity of wastewater, safety circumstances, the supply of disinfectants, investment and operation prices, etc. (Figure 2) [1].

A few months ago, during the current COVID-19 pandemic in China, RNA of SARS-CoV-2 has been detected in feces of patients, which prompted worry to the disinfection of wastewater of appointed hospitals [1]. Researchers [1] accepted that transmission could as well happen by means of fomites in the nearest environment around the infected person. Following former investigations, about the pathogen transmission in wastewater system, scientists [1] affirmed that below specific conditions, the wastewater system possesses the capacity to allow airborne transmission of SARS-CoV-2. Such findings are compatible with the fact in a study that SARS-CoV-2 from a single stool specimen has been cultured [56]. Further, it is as well mentioned that wastewater discharged from a COVID-19 particular hospital was SARS-CoV-2 RNA positive, showing that the virus might infect the drainage system [1]. On the other hand, disinfecting hospital wastes is as well in an elevated emergency because the waste formation augments exponentially throughout this period, which may augment disease diffusion and provoke a gigantic hazard on both medical staffs and patients without appropriate collection and disinfection [1].

There are only a few pieces of research on the demobilization of SARS-Cov-2 to that extent [9]. However, researchers mentioned that the genome of the SARS-CoV-2 strains are phylogenetically nearest to the bat SARS-related coronaviruses, and the Spike protein has a 78% nucleotide identity with the human SARS-Co-1 [1]. Because of the resemblances among SARS-CoV-1 and SARS-CoV-2, the SARS-CoV-2 could as well be vulnerable to either ecological agents or disinfectants. Thus, disinfection techniques embraced throughout the SARS epidemic may be utilized as a perfect reference to killing SARS-Cov-2 in hospital wastewater. SARS coronavirus (SARS-CoV-1) can subsist for 2 days, 3 days, and 17 days in the hospital wastewater, stool, and urine at 20˚C, respectively [57]. All SARS viruses can be neutralized in 30 min at 20˚C with more than 0.5 mg/L residual free chlorine or 2.19 mg/L residual chlorine dioxide left [1]. Scientists juxtaposed disinfection effectiveness of numerous methods and noted that chlorine and UV irradiation were the most performant pursued by chlorine dioxide, for all that efficacy of ozonation was not exemplary. Such a finding was in accord with those observed by Wang et al. [57].

Until January 27, 2020, there have been 1512 COVID-19 designated hospitals all over China [1]. In Wuhan, the local Ministry of Ecology and Environment (MEE) has settled a crisis program for disposal of wastewater from temporary treatment centers, which are freshly constructed COVID-19 specified hospitals for cases with moderate symptoms in Wuhan. Chlorine disinfection (liquid chlorine, chlorine dioxide, and sodium hypochlorite), which has long been employed in hospital wastewater disinfection in China, is embraced in such an agenda. The available chlorine is advised to be about 50 mg/L. For disinfecting the septic tank, the residence period has to be more than 1.5 h with residual chlorine over 6.5 mg/L and fecal coliform colonies less than 100 per liter [1]. Further, UV irradiation [52] and heating [25] are as well proposed for disinfecting wastewater in different COVID-19 selected hospitals due to fewer DBPs and perfect disinfection efficacy [58] [59] [60]. Water standards of wastewater discharged from the hospital have to satisfy the requirements listed in Table 2 [1].

Since any patient, health care worker, or visitor is apt to transmit influenza to vulnerable individuals inside hospitals, hospital-acquired influenza has been a clinical worry. Disinfecting and cleaning medical equipment, surgical instruments,

and hospital environment stay significant actions to avert transmission of influenza virus from hospitals to persons. Jeong et al. [61] assessed the efficiency of disinfection techniques, which can be readily run at hospitals, in killing influenza A virus H1N1 (H1N1). They assessed the influences of 0.1 mol/L NaOH, 70% ethanol, 70% 1-propanol, solvent/detergent (S/D) using 0.3% tri (n-butyl)-phosphate and 1.0% Triton X-100, heat, and ethylene oxide (EO) treatments in neutralizing H1N1. Demobilizing H1N1 was kinetically controlled via the treatment of disinfectants to virus solution. Further, a surface test procedure, which implied drying a quantity of a virus on a surface and then implementing the demobilization processes for 1 min of contact time, was employed to check the virucidal effectiveness.H1N1 was fully demobilized to unnoticeable degrees in 1 min of 70% ethanol, 70% 1-propanol, and S/D treatments in the surface tests as well as in the suspension tests. H1N1 was totally demobilized in 1 min of 0.1 mol/L NaOH treatment in the suspension tests and as well efficiently demobilized in the surface tests with the log reduction factor of 3.7. H1N1 was demobilized to unnoticeable degrees within 5 min, 2.5 min, and 1 min of heat treatment at 70˚C, 80˚C, and 90˚C, respectively in the suspension tests. Also, H1N1 was fully demobilized by EO treatment in the surface tests. Consequently, usual disinfectants, heat, and EO were efficacious in demobilizing H1N1. Such findings were useful in applying efficient disinfecting procedures to avert hospital-acquired infections.

Obtaining efficacious disinfection of waterborne pathogens with reduced poisonous DBPs [62] [63] [64] requires an easy, cost-efficient, and environmentally-friendly technology [65] [66] [67] [68]. Lately, photocatalytic water disinfection has magnetized ever-growing worldwide interest thanks to its strong oxidative potential and encouraging capacity in solar energy usage [69] [70] [71]. Among waterborne pathogens, viruses, which have been found with very small sizes, high risks of illness, and resistant to environmental inactivation/decomposition, constitute a grave menace to public health [59] [72] [73]. During the last three decades (Figure 3), attempts have been dedicated to using photocatalysis to reach real viral demobilization [21] [54] [74]. Despite that photocatalysis has been completely examined for killing bacteria, photocatalytic disinfection of viruses

with quite different compositions, structures, and resistance to oxidative stress compared to bacteria was not consistently detailed (Figure 4). Zhang et al. [75] suggested a summary of antiviral impacts of a large variety of photocatalysts, comprising TiO₂-based, metal-containing (other than TiO₂), and metal-free photocatalysts. Further, they recapitulated the advance of photocatalytic reactors for viral demobilization to encourage handy utilizations for disinfecting water (Figure 5). Moreover, they discussed the pivotal pathways that dictate the effectiveness of photocatalytic viral disinfection.

Zheng et al. [76] employed bacteriophage f2 and its host E. coli 285 as the model microorganisms and examined the disinfection efficiency of prepared Cu-TiO₂ nanofibers below visible light. They found that the prepared Cu-TiO₂ nanofibers depicted an excellent capability in eliminating bacteriophage f2 and E. coli below visible light. Initial pH did not influence the photocatalytic disinfection efficacy importantly. In a particular domain, the reduction performance of bacteriophage f2 augmented with the elevation of catalyst dosage, light intensity, and temperature; however, it diminished with the elevation of the initial virus level. In virus/bacteria mixed combination, bacteriophage f2 manifested more powerful resistance to photocatalytic oxidation than E. coli and the reduction of bacteriophage f2 was clearly influenced by being mixed with E. coli; however, the elimination of E. coli nearly stayed unaltered after being mixed with bacteriophage f2. Competitive adsorption in the mixed system contributed to E. coli demobilization, whilst the free reactive oxygen species (ROSs) in the bulk phase greatly participated in phage f2 demobilization.

In water and wastewater treatment, coagulation [77] [78] [79], oxidation [49] [50] [54], and disinfection [9] [48] [59] are primary methods [64] [68] [80]. A chemical that could be utilized for all the above-mentioned targets is ferrate(VI). Talaiekhozani et al. [81] reviewed ferrate(VI) formation, measurement, stability, mutagenicity, and utilization in coagulation [82] [83] [84], oxidation, and disinfection. Diverse electrochemical devices that could be employed for ferrate(VI) generation have been presented [85] [86] [87].

Ferrate(VI) salt could disinfect water and oxidize organic and inorganic pollution concurrently [81] [88]. Indeed, ferrate(VI) could neutralize pathogens in two fashions: 1) as ferrate(VI) is a powerful oxidizer, it could oxidize cell wall,

protoplasm, DNA, and different vital microorganism organs which eliminates them at once [37] [38]. 2) Ferrate(VI) is progressively transformed to Fe(III) [89] [90] [91] which is a powerful coagulant; thus, colloids comprising microbes are coagulated and eliminated from the water [92] [93] [94]. Small amounts of ferrate(VI) could coagulate colloids and oxidize soluble pollutants simultaneously [74] [80] [81]. Such features oblige potassium ferrate as a suitable replacement for diverse conventional disinfectants [74] [80] [95]. In the dosage varying from 0 to 50 mg/L, ferrate(VI) could neutralize all microbes in water [81]. Ferrate(VI) could totally disinfect water carrying E. coli [81]. Concerning viruses elimination, numerous researches have established the capacity of ferrate(VI) for killing such pathogens. The potential of ferrate(VI) to remove the f2 coliphage virus was proved [81]. Indeed, 99% of f2 coliphage is neutralized in water carrying 1 mg/l ferrate (VI), pH of 7.8 after 22 min. Such a contact period is decreased to 5.7 and 0.77 min when pH is diminished to 6.9 and 5.9, respectively. Further, 99.9% elimination yield was reached with ferrate(VI) injection of 10 mg/L, pH of 7.8, and the retention period of 30 min. Such a green product remains much more efficacious as a disinfectant than chlorine, whilst no potassium ferrate sediments were found in the disinfection region. The production of sediments in the disinfection method stays an additional major drawback of employing chlorine besides DBPs formation.

Hospital wastewater (as well as the sludge) must be treated and disinfected completely prior to discharge [1]. Without disinfection, they should not be left to be randomly discharged or utilized as agricultural fertilizers. Employing any infiltration wells/pits to discharge wastewater and sludge, or the discharge into sanitary protection zone of drinking water sources must as well be harshly barred. Further, the government must adopt actions to ameliorate the management of hospital wastewater, particularly throughout the COVID-19 pandemic. The hospital must set up a recycling system and assign special personnel to take charge, and strengthen the management of each department to ban waste loss. Personnel implicated in the disposal of disposable medical supplies must be qualified and strengthened in personal protection. Lately, several novel signs of progress have as well been performed in hospital wastewater treatment engineering, like radiation disinfection technique, reverse polymerization disinfection process, plasma disinfection method, and thermal gasification disinfection procedure. Such technologies possess important promotion value; however, because of the elevated investment costs, such techniques have not been employed at a large scale. With ameliorating hospital wastewater disinfection processes, the prices of disinfection will persist to lower, and side contamination to nature will be progressively dominated. In the course of the disinfection, the ecological contamination or influences on human health could be greatly decreased if the procedure accurately complies with the requirements. With a view to improving more secure, efficient, economical disinfection technologies, the local natural and real circumstances must be taken into account in the next investigations [1].

This research has been funded by the Research Deanship of University of Ha’il, Saudi Arabia, through the Project RG-191190.

The authors declare no conflicts of interest regarding the publication of this paper.

Ghernaout, D. and Elboughdiri, N. (2020) Urgent Proposals for Disinfecting Hospital Wastewaters during COVID-19 Pandemic. Open Access Library Journal, 7: e6373. https://doi.org/10.4236/oalib.1106373