Treated Wastewater Research Articles

Performance of Covid-19 Waste Management at Health Service Facilities in North Toraja Regency

Community health centers are the frontliners of healthcare services which in its activities produces medical waste and non-medical waste both in solid and liquid form. This waste needs to be managed in accordance with existing regulations where environmental management must be carried out systematically and sustainably. Regarding the management of Covid-19 medical waste in the health facilities of North Toraja Regency, this study aims to determine the management process, management constraints and compare the management of wastewater and hazardous and toxic solid medical waste generated from handling Covid-19 patients at hospitals and health centers in Toraja Regency. North. The research method used is descriptive research method with case study design. Data collection techniques are carried out by observations, interviews, and documentation of secondary data. The results show that the management of hazardous and toxic solid medical waste water and waste for Covid-19 patients in private hospitals leaves the processing to third parties and government hospitals destroy solid hazardous medical waste with incinerators, while at community health center the wastewater is directly discharged into water bodies and medical hazardous waste. handed over to a third party. The process of treating waste water and hazardous and toxic solid medical waste for Covid-19 patients at the health facilities of North Toraja Regency has not been in accordance with the guidelines issued by the Indonesian Ministry of Health. The main obstacle in processing solid medical waste water and hazardous waste for Covid-19 patients at the health facilities of North Toraja Regency is the lacking of operational costs and delays in disbursing operational costs. Government-owned hospitals were found to be slow to comply the Covid-19 Health Facilities Waste Management Guidelines issued by the Ministry of Health of the Republic of Indonesia.

Effect of Surface and Subsurface Drip Irrigation with Treated Wastewater on Soil and Water Productivity of Okra (Abemoschus esculentus) Crop in Semi-Arid Region of Tunisia

Under semi-arid conditions, irrigated agriculture faces hard competition for water. It is against this backdrop that appropriate management of irrigation techniques and water resources becomes a major concern. This study investigated the effect of surface (SDI) and subsurface drip irrigation (SSDI) with domestic treated wastewater (TWW) and fresh water (FW) on soil water dynamics, salinity, yield, and mineral nutrition of okra. The experimental design was set-up based on two adjacent plots according to the water quality: Fresh Water (FW) T1 and domestic Treated Wastewater (TWW) T2. Results showed that measured soil water contents (SWCs), under TWW treatment (T2), were greater than their corresponding measurements under FW (T1), and in particular at 35 cm depth. Meanwhile, for both water qualities, soil Electrical Conductivity (EC) registered at 5 cm depth was higher than those measured at 35 cm, with values ranging from 0.14 to 0.36 mS·cm−1 and from 0.20 to 0.47 mS·cm−m for T1 and T2, respectively. Regarding crop yield, a statistically significant increase (p = 0.05) in okra fresh yield was observed when TWW was used. Fresh yield in SDI was 2.55 t·ha−1 and 3.9 t·ha−1 in T1 and T2, respectively. Nevertheless, results indicated that lateral depth did not significantly affect okra fresh yield. Moreover, a significant higher irrigation water productivity (WPirrig) with TWW (1.08 ± 0.26 and 1.23 ± 0.18 kg m−1) was observed, which was nearly double those obtained with FW (0.72 ± 0.33 to 0.78 ± 0.18 kg m−1). Appropriate use of SSDI with TWW stands as an irrigation management technique to improve yield and irrigation water productivity of okra crops.

Effect of long-term treated wastewater irrigation on soil sodium levels and table grapevines' health

The use of treated wastewater (TWW) for irrigation is constantly on the rise, while the long-term impacts are not in consensus. In this study we examined the impact of 9 years of municipal TWW irrigation on sodium (Na) and sodium adsorption ratio (SAR) in a vineyard soil and consequently on table grapevines. Our objectives were to: 1) quantify multiannual temporal trends of Na and SAR; 2) construct a regression model to define the relative contribution of various factors on Na and SAR levels in the soil; and 3) determine Na and SAR accumulation impact on the grapevines’ health state (healthy, damaged, or dead). Our analyses indicated that long-term irrigation with TWW resulted in Na accumulation in the soil, with enhanced effects attributed to higher rainfall levels (precipitation levels). Applying TWW for irrigation was also found to affect vines as evident with observations of damaged and dead vines after 9 years, ranging between 25% and 40% mortality rates depending on the treatment used. These observations were found to be directly and significantly associated with higher Na concentrations (p-values of 0.008 and 0.011 compared to damaged and healthy vines, respectively). Our results, although specific to the region, raise a warning sign and merit further long-term investigations of TWW irrigation. This is essential to guarantee that use of TWW irrigation does not cause irreversible damage to farmlands potentially threatening soil health and food security.

Performance and Evaluation of Sewage Treatment Plant Based on MBBR and EBB Technologies

Abstract: The rapid expansion of modern housing and industrialization around the cities has polluted environment. This trend was observed in many developed countries in the beginning of nineteenth century which resulted in the contamination of air, water, soil etc. with pollutants. If the pollutants are released in the environment and left untreated they would cause serious diseases in both humans and animals. Large scale pollution of water bodies around the globe became a major problem due to release of industrial and domestic waste directly in water streams. To prevent the leaching of pollutants in the ground water scientist developed various methods of wastewater treatment based on the hazardous chemicals and microorganisms, which were present in the untreated water. Modern sewage treatment plants were installed in big cities to treat the water released from households. Most STPs were designed based on the stringent criteria to check the pollutants levels in the treated water so that when it is released or recycled it is safe to the environment. Modern day STP plants have a high cost of operation due to huge power consumption. In order to reduce the pollutant levels in the wastewater this study was conducted using a Eco Bio Block (EBB) techniques with aeration and without aeration. A comparison of EBB was also carried out with MBBR technique. Our results show that when EBB technique was applied with aeration it is effective in reducing pollutant levels in the wastewater akin to MBBR. In addition, we tested the EBB without aeration and found that the treated waste water has relatively low levels of BOD, COD and turbidity, suggesting that the treated water can be utilized for landscaping and horticulture activities. Overall, the outcomes from this study are encouraging to adopt EBB in smaller towns and in small housing societies to treat the wastewater prior to release

Evaluating the Social and Psychological Factors about the Public Acceptance of Treated Wastewater Reuse: A Review

Evaluating the Social and Psychological Factors about the Public Acceptance of Treated Wastewater Reuse: A Review

Effect of bio-stimulants on growth and chemical composition of mahogany seedlings grown under treated wastewater (TWW)

A pot experiment was carried out to study the effect of treated waste water (TWW) on mahogany seedlings and the role of bio-stimulants in alleviating the harmful impacts, using –6- months' old seedlings. The TWW was used in 3 types coded as 75%WW/25%PW, 50%WW/50%PW and 25%WW/75%PW, according the ratio between treated wastewater (WW) and potable water (PW). All seedlings grown under the different types of TWW treatments were sprayed with some bio stimulants. The results revealed that irrigating mahogany seedlings with 25WW/ 75PW, significantly increased plant height, improved the formation of leaves, fresh weight leaves, 25WW/ 75PW increased total indoles whereas using 75WW/25PW or 50WW/50PW, for irrigation produced thicker and heavier FW of stems. FW of leaves with 50WW/50PW gave the heaviest fresh and dry weights of leave and roots diameter, total phenols, free proline and total soluble sugars. The treatment of 75WW/25PW formed significantly longer roots, both 75WW/25PW 0r 50WW/50PW, insignificantly increased fresh weight of roots. All bio-stimulants significantly increased plant height and seaweed extract, salicylic acid and Pot. silicate were the most effective. PS treatment exhibited the thickest stems.

Mortar mixing using treated wastewater feasibility

• The mortars based on CEMI and CEM II and treated wastewater had a slight increase in setting times. • Treated wastewaters had a slight impact on fresh mortar density for various cement types. • Mortars based on CEM III cement and treated wastewater have better mechanical performance. • The pouzzolanic reactions for mortar made with CEMIII cement and wastewater that produce a supplementary CSH and ettringite in long term. Water scarcity is considered to be one of the most important problems faced by the world today. To alleviate this problem, it is important to study the feasibility of replacing partially or completely potable water for concrete production by treated wastewater. This paper studies the feasibility of using treated wastewater (TWW) from the Artois-Picardy Water Agency in Douai (Hauts de France-France region) for mortar mixing. The aims of this study is to limit watercourse discharges, reduce groundwater over-exploitation, and minimize natural resource pollution. To do this, three series of mortar mixtures have been formulated according to the NF EN 196 standard, varying the type of cement (CEMI CEMII and CEMIII) and mixed with treated wastewaters with a 0.5 water to cement (W / C) ratio. The performance of these mortar mixes were compared to the control ones (mixed with “drinking water” (DW)). The Experimental work included the workability, setting time, and density of different mortar mix designs using treated wastewater. In addition, the dynamic modulus of the mortar (Edyn) was determined, as well as the mechanical properties (compressive and flexural strength) at 7, 28, 60, 90, and 360 days after the mortar samples were made. Furthermore, the environmental assessment of the hardened mortars was evaluated by leaching tests according to the EN 1245–74 standard. The results obtained shown that TWWs had no adverse effect on physical properties (curing time, slump, porosity distribution, and density) of these mortars. On the other hand, the mortar mechanical properties were slightly lower than those of the control for samples made with cement CEM I and CEM II. However, a significant compressive strength increase was recorded for mortars made with CEM III cement. The mortar curing time, slump, and density made with TWW were closer to those of the control.. The hardened mortars were then analyzed by scanning electron microscopy (SEM), and by Thermogravimetric Analysis (TGA) and differential Thermogravimetric Analysis (DTA). According to the obtained findings, the TWW of the city of Douai France could be used for the manufacture of mortar and concrete.

Prevention and treatment of drip emitter clogging: a review of various innovative methods

Abstract Various new and innovative methods of prevention and treatment of emitter clogging were demonstrated by researchers in recent years. A total of nine such innovative approaches were reviewed, classifying them under three broad categories, viz., physical, chemical and biological methods. Though flushing of laterals is a known method, it was found that increasing its frequency and at higher pressures improved the emission rate and uniformity of the emitters significantly. When Treated Waste Water (TWW) is used for irrigation, flushing with fresh water after every five irrigations effectively removed the emitter clogging. Among the various physical methods reviewed, use of MERUS ring, application of pulsating pressure with triangular wavefront and ultrasound treatment were found to be effective in removing composite clogging problem in drip emitters. Among the chemical methods, fertigation using urea phosphate (UP) at low concentrations for longer periods reduced the pH of irrigation water and contributed to the removal of chemical precipitates from the lateral pipes and emitters. Use of antagonist Bacillus bacterial strains helped in removing not only CaCO3 precipitation but also biofouling due to the use of TWW in the drip systems. However, this method needs to be further developed and optimized for its effectiveness and replicability.

High-speed treatment of low strength domestic wastewater for irrigation water production in pilot-scale classical, moving bed and fixed bed hybrid MBRs

To evaluate the treatability of domestic wastewater under conditions of low hydraulic retention time and high organic loadings, 3 pilot-scale automatically controlled membrane bioreactors (MBRs) as classical (C-MBR), moving bed (MB-MBR), and fixed bed (FB-MBR) were established and operated for a total of 268 days. Established pilot plants were compared in terms of treatment performance, membrane fouling, irrigation water criteria, and power consumption values. Results obtained have shown that all three systems were able to achieve more than 93% removal of chemical oxygen demand (COD) in an average hydraulic retention time (HRT) of 1 hour, and MB-MBR and FB-MBR were superior in terms of total nitrogen (TN) and total phosphorus (TP) removals. It has been determined that MB-MBR and FB-MBR are also advantageous in terms of power consumption. Especially it has been found that FB-MBR can produce better quality irrigation water with 40% lower power consumption than C-MBR under the same conditions. It was concluded that biofilm-supported hybrid systems could be a practical application in the fight against increasing water scarcity and global warming, both in obtaining clean water with less power consumption and in protecting human and environmental health.

Effect of water quality on the biomass production, nutritional value, and contents of secondary compounds of three genotypes of willow (Salix acmophylla Boiss.) grown for fodder

Shrub willow (Salix spp.) grow naturally in riparian landscapes and combine rapid growth with high rates of evapotranspiration. As willow irrigated with secondary treated wastewater (TWW) can be used as fodder for goats, it could be exploited in otherwise dry areas where such water is available. We examined the effect of irrigating Salix acmophylla Boiss. With secondary treated wastewater (TWW) or municipal freshwater (FW) on growth indices, secondary compounds, and nutritional value of willow fodder over two years grown in 50 L pots in natural soil under ambient conditions. We evaluated ten willow ecotypes belonging to three genotypes (GA, GB, and GC). Biomass production greatly differed among ecotypes. TWW irrigation resulted in a doubling in biomass production, compared with FW. In GA and GC shrubs, the leaf/total weight ratio was higher than in GB. The differences in crude protein (CP) and the in vitro dry matter digestibility (IVDMD) were 2 % and 3 % (in percentage points, on DM basis) higher respectively in plants irrigated with TWW over FW. Salicin and catechin contents were also greater under irrigation with TWW compared with FW. GC produced less salicinoids, in opposite to chlorogenic acid. Overall, genotype did not affect nutritional value but GC shrubs had more resprouting stems and produced more biomass. Our results suggest that willow genotype is important for biomass and secondary compound production and should be taken into account before large-scale planting. Willow crops irrigated with TWW could produce appreciable biomass and quality fodder for livestock under semi-arid and arid conditions.

Wastewater reuse for tree irrigation: Influence on rhizosphere microbial communities

Irrigation water can increase tree biomass production, but it is often unavailable near grove locations. Alternative water resources, such as treated wastewater (TWW), offer a potential solution, while additionally contributing to a circular economy. To assess environmental sustainability, the impact of residual wastewater contaminants on soil microorganisms must be understood. This study compared soil microbial communities from purpose-grown tree groves irrigated with TWW for at least ten years, with communities from unirrigated control plots. Short-term batch testing was conducted to compare the degradation capabilities for five trace-level organic contaminants (TOrCs) associated with reclaimed wastewater. Microbial community composition was examined using 16S rRNA Illumina sequencing. Microbial biomass and abundance of a putative bisphenol A (BPA) degradation gene were quantified via droplet digital PCR. Principal component analysis of the sequencing results revealed distinct clustering of the irrigated and non-irrigated communities at two sites. Control soils from all sites exhibited intrinsic degradation of BPA and ibuprofen. Additionally, several OTUs of the Acidobacteria and Proteobacteria were correlated with soil organic carbon and TOrC degradation. Together, these results suggested that rhizosphere microbial communities were altered in long-term wastewater infiltration galleries, though the impacts of increased soil moisture due to irrigation and the effects of exposure to residual contaminants are difficult to separate. A greater understanding of TWW impacts on soil microbial communities will help expand the prevalence of wastewater reuse for biomass production, contributing to the growth of the circular economy. • Treated wastewater irrigation correlated with changes to soil bacterial communities. • Soil microbial communities intrinsically degraded bisphenol A and ibuprofen. • Moisture, carbon, and tree species may shape communities in infiltration galleries. • Droplet digital PCR was used to quantify microbial biomass in soil samples.

High−saline and long−term treatability of industrial wastewater by AnOMBR using organic and inorganic draw solutions

Less costly to AnMBR, anaerobic osmotic membrane bioreactor (AnOMBR) proceeds water and energy−efficient progresses within green and cleaner technologies. Long−term effectively operation of AnOMBR in high salinities due to salt accumulation is of the greatest priority, accompanied with a cost−performance efficient and non−inhibitory draw solution (DS) usage. Operational stability of AnOMBR in industrial wastewater treatment was studied at 30 mS/cm using the most favorable organic and inorganic DS within 29 DSs in our prior work, namely HCOONa and CaCl2. Osmotic and microbial yields during unintervented operations were lost due to severe salt stress and membrane biofouling. With a virgin membrane replacement, removal efficiencies, water and salt flux selectivity were partially restored, but the AnOMBRs turned towards collapse due to microbial activity lost. Therefore, sludge inoculation was applied and improved all AnOMBR performances to levels so close to before losses with 78 ± 3 % COD and 98.3 ± 0.6 % PO43-–P, 0.44 ± 0.2 L CH4/d excluding NH4+–N of 44 ± 10 %. It was designated that reverse salt passage for both the DS was responsible for approximately two-thirds of in-reactor salt build-up during stable AnOMBR operations. Statistical analysis results of the AnOMBR system for HCOONa and CaCl2 showed that statistical significances of performances in treatments with both DSs were from moderate to strong evidence levels. Microbial diversity increased by salt accumulation, and archaeal community differentiated. HCOONa promoted hydrogenotrophic halotolerant methanogenic archaeas, but not by CaCl2. Biofilm formed predominantly by biomass, Na+/Ca2+−bound biopolimers and inorganic precipitates provided bioactively better C, N, and P exhaustions in more porous and thicker secondary membrane layer by HCOONa. Beyond a virgin membrane replacement and sludge inoculation, an AnOMBR can be efficiently operated by sludge acclimation to high salinities, finest membrane clean-up, and even fabrication of FO membrane with the integrated nano-structured novel membranes such as including silver, nanofibers, graphene oxides etc.

Assessment of the application of cladode cactus mucilage flocculants for hot chemical degreasing electroplating wastewater treatment and reuse: process efficiency and storage stability.

Pressures related to urban growth and industrial activities exacerbated by climate change had an impact on water resources in Tunisia. The present study examines the application of cladode cactus mucilage (CCM) flocculants for hot alkaline chemical degreasing Zn-electroplating wastewater treatment and reuse (WWTR). The CCM flocculation process was selected through their environmental benefits, economic facilities, sustainable use of the natural biopolymer product, input biopolymers substitution, and on-site treated wastewater (TWW) reuse and recovery. The alum coagulation and CCM flocculation were performed by the jar test series. The suitability of treated wastewater quality (TWWQ) with alum/CCM was also assessed for reuse purpose in terms of corrosion-scaling indices (RSI, LSI, PSI, AI), oxidation-reduction potential (ORP), and microbiological community growth (Bacillus, Pseudomonas, Mesophilic bacteria and yeasts) for 28 days storage at 25 °C. The total alkalinity removal efficiency reached 95.8% with an optimum dosage of alum + CCM for hot alkaline chemical degreasing wastewater bath rinsing. The results showed that the stability of TWWQ has significantly deteriorated during storage leading to aggressive wastewater, pathogen growth, and biological malodor production which make them unsuitable for reuse. Therefore, there is a need for CCM processing alternatives that preserve the physico-chemical and microbial of TWW properties during storage.

The Interreg Project AdSWiM: Managed Use of Treated Wastewater for the Quality of the Adriatic Sea

The Italy-Croatia Cross Border Cooperation (CBC) Programme is the financial instrument supporting the cooperation between the two European Member States overlooking the Adriatic Sea. The first call for proposals was launched in 2017, identifying four priority axes of intervention. Subsequently, in 2019, the kick-off of the AdSWiM project “Managed use of treated urban wastewater for the quality of the Adriatic Sea” took place in Udine (IT). Adriatic marine waters are generally classified as good to excellent based on the Bathing Water Directive (2006/7/EC). Nevertheless, issues of low productivity or the lack of nutrients have been often suggested, especially on the Italian side. The project addresses the question of whether wastewater treatment plants (WWTPs) discharging to the sea, after applying appropriate pollution control and management technologies, can modulate the nutrient content of their effluents to support localized depleted areas. This idea is borrowed from one of the motivations that support the reuse of treated wastewater for irrigation, thus leading to the return of nutrients (nitrogen, phosphorus, potassium, etc.) to natural biogeochemical cycles. However, the hypothesis of modulating the nutrient composition of wastewater opens up to several critical aspects, including legislative and technological ones. Being aware of the delicate environmental implications, we have undertaken the project involving WWTPs, research centers, municipalities, and legal experts with the aim of investigating in detail the problems related to wastewater reuse, especially with regard to the content of nutrients. Our experimental approach aimed to evaluate appropriate and possibly new treatment technologies to reduce the microbial load and to implement chemical and microbiological tests on the treated wastewater. Results have shown that it can be tricky to draw decisive conclusions because (i) the wastewater management systems differ between the two sides of the Adriatic sea due to the different levels of technological development of WWTPs; (ii) the Italian and Croatian coasts deeply differ in geographic characteristics (i.e., topography, orography, current circuits, presence of rivers) and anthropogenic pressure (i.e., exploitation levels, population density); (iii) the new treatment technologies to lower bacterial contamination need further efforts to raise their technological level of readiness (TRL) and make them implementable in the existing WWTPs. However, in terms of chemical control methodologies, the proposed sensors and biosensors gave positive results, managing to decrease the detection limits for the measured parameters, and the tested technologies for microbiological monitoring were also effective. In particular, the latter was carried out by using recent molecular biology techniques, capable of resolving the microbiota in treated wastewater, which emerged to be strictly related to the features of the WWTPs.

Treatment of agro-food industrial waste streams using osmotic microbial fuel cells: Performance and potential improvement measures

Osmotic microbial fuel cell (OsMFC) is an emerging wastewater treatment technology which incorporates multiple functions such as bioelectricity generation, organic substrate removal, and wastewater reclamation. This study firstly reported the performance and potential improvement measures of OsMFCs in treating selected agro-food industrial waste streams, i.e., brewery wastewater (BW), sweetener process wastewater (ST), and swine wastewater (SW). BW and SW wastewaters with good biodegradability, showed high power density (11.1 and 9.3 W/m 3 ) and soluble chemical oxidation demand (sCOD) removal (89.2 ± 4.1 and 70.9 ± 3.8%) in OsMFCs. In contrast, OsMFC showed low performance with ST wastewater despite its high sCOD load. Possibilities in improving the treatment performance through modifying the operational and process settings were further explored. Shortening anode hydraulic retention time (HRT) was able to improve the bioelectricity generation and water production, whereas slightly compensated the sCOD and nutrient removal efficiencies. However, this approach showed limited effect in enhancing the ST-OsMFC. A pre-fermentation process with a minimum HRT of approximately 20 h was recommended to enhance the treatability of ST wastewater by previously converting the complex organic substrates in the raw water into volatile fatty acid (VFA). • First report in OsMFC treating industrial wastewater. • Treatment of different agro-food industrial waste streams by OsMFC was demonstrated. • An anode HRT of 9 h is recommended for OsMFC treating selected agro-food waste streams. • Pre-fermentation is an option to improve the treatability of sweetener wastewater in OsMFC.

Enhanced catalytic reduction/degradation of organic pollutants and antimicrobial activity with metallic nanoparticles immobilized on copolymer modified with NaY zeolite films

Toxic organic pollutants are the major cause of water pollution. Thus, finding a reliable technology for the removal of such pollutants is one of the global priorities for the protection of the natural environment and human health. The MNP’s with low-cost and high catalytic efficiency loaded on self-assembled polymeric membranes are promising approach to treat waste water because of their outstanding properties. In this work, novel polystyrene-b-polyisoprene-b-polystyrene block copolymer (BP) virgin and modified composites with NaY zeolite (BP-NaY) were successfully prepared via a simple solution casting method for immobilization of the metal nanoparticles (MNPs). Both the films were impregnated with zero-valent Cu, Ag and CuAg nanoparticles (NPs). The synthesized catalysts were analyzed through FESEM, EDS, FTIR and XRD. The impregnated metal ions on BP or BP-NaY nanocomposites thin films were converted to their corresponding zero-valent metal NPs by using NaBH4 as a reductant and were evaluated for their catalytic activity in the reduction of various organic pollutants including dyes (MO, CR, MB, ARS), nitroarenes (4-NP, 4-NA, 2/3/4-NB) and antibiotic cefixime. Based on pseudo-first-order kinetics, the rate constant value “kapp” was highest for [email protected] catalyst against all pollutants i.e. 14.7 × 10−1, 40.6 × 10−1, 17.5 × 10−1, 11.6 × 10−1, 12.7 × 10−1, 6.4 × 10−1, 13.2 × 10−1 min−1 for 4-NP, 4-NA, MO, ARS, MB, CR and cefixime respectively. The effect of various parameters on pollutants removal and concurrent degradation of dyes and nitroarenes were also investigated. Catalyst proved to be stable as a slight reduction in the catalyst activity was observed during recyclability. Moreover, the [email protected] showed 19- and 22-mm zone of inhibition against Escheria coli and Staphylococcus aureus respectively. Thus, this study highlighted the catalytic potential of the prepared MNPs in water treatment applications.

Effective removal of organics from Bayer liquor through combined sonolysis and ozonation: Kinetics and mechanism

The presence of organic compounds in the waste liquor is of serious environmental concern that has plagued the development of alumina industry (Bayer Process). The present work attempts to develop a green and efficient process for removal of organics utilizing combined effect of sonolysis and ozonation (US/O3). The effects of reaction duration, ozone concentration and ultrasonic power are assessed for sonolysis (US), ozonation (O3) and combination of sonolysis and ozonation (US/O3). The optimal conditions for US/O3 treatment system is identified to be a reaction duration of 7 h, ozone concentration of 7.65 g/h, and ultrasonic power of 600 W. The total organic carbon (TOC) removal and decolorization are 60.13% and 87.1%, respectively. The process can be scaled-up to industrial scale, which could potentially serve to be a convenient, safe and sustainable alternative to the exisiting treatment technologies. Additionally, the treated waste water can be reused contributing to an improvement in the overall economics.

Evaluation of the Toxicity of Cafeteria Wastewater Treated by a Coupled System (ARFB-SD)

In developing countries, achieving greater coverage in the treatment and safe reuse of graywater is a pending task. Therefore, this article presents the results obtained from cafeteria wastewater treatability tests and effluent toxicity tests. For the treatment, a serial system was applied: an aged refuse filled bioreactor (ARFB) and a solar distiller (SD). In the first stage (ARFB), two hydraulic loads (HLs) were tested (200 and 400 L/m3·day), the latter being the best of them, with an average decrease of 95.7% in chemical oxygen demand (COD). In the second stage (SD), the decrease was 62.8%, resulting in a final effluent with 67.7 mg/L COD, which corresponded to a global COD decrease of 97.4%. For the toxicity tests, radish seeds were used in the serial system effluent, obtaining a relative seed germination (RSG) rate of 93.3% compared to 80% obtained in the ARFB effluent. For the percentage germination index (PGI), it was determined that both effluents (ARFB and ARFB-SD) presented a toxicity considered low, especially the ARFB-SD effluent whose PGI value was close to zero (−0.0667). The results obtained showed not only that the ARFB-SD system is efficient in removing the high organic load that can go along with cafeteria wastewater, but also that it can provide an effluent with a very low toxicity level based on the PGI close to zero.

Effect of irrigation with treated wastewater on bermudagrass (Cynodon dactylon (L.) Pers.) production and soil characteristics and estimation of plant nutritional input.

In recent years, climate change has greatly affected rainfall and air temperature levels leading to a reduction in water resources in Southern Europe. This fact has emphasized the need to focus on the use of non-conventional water resources for agricultural irrigation. The reuse of treated wastewater (TWW) can represent a sustainable solution, reducing the consumption of freshwater (FW) and the need for mineral fertilisers. The main aim of this study was to assess, in a three-year period, the effects of TWW irrigation compared to FW on the biomass production of bermudagrass [Cynodon dactylon (L.) Pers.] plants and soil characteristics and to estimate the nutritional input provided by TWW irrigation. TWW was obtained by a constructed wetland system (CWs) which was used to treat urban wastewater. The system had a total surface area of 100 m2. An experimental field of bermudagrass was set up close to the system in a Sicilian location (Italy), using a split-plot design for a two-factor experiment with three replications. Results highlighted a high organic pollutant removal [five days biochemical oxygen demand (BOD5): 61%, chemical oxygen demand (COD): 65%] and a good efficiency in nutrients [total nitrogen (TN): 50%, total phosphorus (TP): 42%] of the CWs. Plants irrigated with TWW showed higher dry aboveground dry-weight (1259.3 kg ha-1) than those irrigated with FW (942.2 kg ha-1), on average. TWW irrigation approximately allowed a saving of 50.0 kg TN ha-1 year-1, 24.0 kg TP ha-1 year-1 and 29.0 kg K ha-1 year-1 on average with respect to commonly used N-P-K fertilisation programme for bermudagrass in the Mediterranean region. Soil salinity increased significantly (p ≤ 0.01) over the years and was detected to be higher in TWW-irrigated plots (+6.34%) in comparison with FW-irrigated plots. Our findings demonstrate that medium-term TWW irrigation increases the biomass production of bermudagrass turf and contributes to save significant amounts of nutrients, providing a series of agronomic and environmental benefits.

Electrochemical Reactivity Investigation of Urea Oxidation Reaction in Nichrome/Nitrogen Doped Carbon Nanofibers Synthesized by CVD Method

AbstractUrea oxidation reaction (UOR) catalysts are being extensively studied due to the affordability, effortlessness of storage and shipment, non‐toxic and non‐combustible characteristics of urea. Additionally, urine and urea‐containing wastes are being explored as fuels, sources for generating electricity and treating waste water simultaneously in urea fuel cells (UFC). Herein, we report the urea oxidation reaction detected for nitrogen (N) doped carbon nanofibers (CNFs) grown on nichrome (NiCr) foil by chemical vapor deposition (CVD) method and study its various electrochemical parameters to determine its capability as urea fuel cell catalyst. Nickel (Ni) and chromium (Cr) metal particles were observed inside the CNFs structure as an alloy. Ni has been reported to be the most promising catalysts among transition metal catalysts. In this study, we have explored the possibility of a bimetallic transition metal/nitrogen doped carbon supported catalyst to overcome the large overpotentials exhibited by individual Ni‐based catalysts for urea oxidation. The Tafel slope was found to be 640 mV/dec with diffusion coefficient D equal to 4.312×10−13 cm2/s and the anodic transfer coefficient equal to 0.472. The charge transfer impedance was also calculated at 0 V and 0.4 V (onset potential) from the Nyquist plots. Our study revealed that NiCr NCNFs (Nichrome/nitrogen doped carbon nanofibers) exhibited significant UOR in variable molar concentrations of urea in 1 M KOH, making it a suitable candidate for urea oxidation reaction.