Feasibility Studies on Treatment of Household Greywater Using Phytoremediation Plants

Recycling and reusing of wastewater acquired high priority among the research community to meet the ever-increasing demand for groundwater, and to tackle water scarcity in every country. In this scenario, a grey water treatment system is developed with a vertical flow wetland construction tank (VFWCT)with sand, gravel and silex as media combined with phytoremediation technology using plants like Cyperus rotundus, Canna indica, Typha angustifolia, Cyperus pangorei, and Phragmites australis. The assessment parameters like color, odor, temperature, pH, electrical conductivity, free residual chlorine, Total Dissolved Solids (TDS), chloride, Sulphate, Total Suspended Solids (TSS),oil & grease, Sulphide,Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nitrate Nitrogen, E.coli and Salmonella are used to substantiate the performance of proposed greywater treatment system. Simulation outcomes showed that most of the guideline values of the effluent are notably lower compared to the influent. The experimentation also focused on finding the best plant as Typha angustifolia for greywater treatment in the VFWCT. The plant’s rapid growth and the removal efficiency parameters of the plant with regard to the contaminants present in the greywater was highly notable. The removal efficiency was 56.56% and 50.25% for BOD5 and COD, the solids content TSS and TDS was 68% and 64.4%. The salt Cl− and Na+ removal efficiencies are 63.4% and 81.39% respectively. Majority of the parameters like pH value, Electrical conductivity, odor and TDS are higher than the groundwater aquifers, but falls within the world health organization safety limits.

Comparison of commercial disinfectants and an in loco-produced solution: free residual chlorine decay in human supply waters

Disinfection process is used in the treatment of water for human supply to promote sanitary safety and provide users with drinking water that meets potability standards. Thus, it is necessary to sustain a minimal concentration of free residual chlorine (FRC) throughout the entire distribution system. The present study investigated the decay process of FRC concentration in water destined for human supply. The decay was evaluated in bench-scale testing, using sodium hypochlorite, calcium hypochlorite, sodium dichloroisocyanurate (organic chlorine) as disinfectant agents, and also an alternative disinfectant solution (ADS) produced in loco, with oxidizing and disinfectant properties, which is being used in Brazilian sanitation industry. To evaluate the decay, four models were fitted: first-order, nth-order, limited first-order and parallel first-order, hence determining the corresponding parameters which describe the decay speed of the FRC concentration in water. Achieved results demonstrated that all models were statistically significant and predictive. However, parallel first-order model produced the best fit. Regarding the evaluated disinfectants, it was noted the preeminence of ADS solution when compared to the others, since it imparted a higher FRC over time, a behavior indicated by lower values for reaction rate constant in all models and when compared to other disinfectants used in this study.

Quantification of Hypochlorite in Water Using the Nutritional Food Additive Pyridoxamine

Chlorine is a widely used disinfectant and oxidant used for an array of municipal and industrial applications, including potable water, swimming pools, and cleaning of membranes. The most popular method to verify the concentration of free chlorine is the colorimetric method based on DPD (N, N-diethyl-p-phenylenediamine), which is fast and reasonably cheap, but DPD and its product are potentially toxic. Therefore, a novel, environmentally friendly colorimetric method for the quantification of residual chlorine based on the food additive pyridoxamine (4-(aminomethyl)-5-(hydroxymethyl)-2-methylpyridin-3-ol) was investigated. Pyridoxamine is a B6 vitamin with an absorption maximum at 324 nm and fluorescence emission at 396 nm. Pyridoxamine reacts rapidly and selectively with free chlorine, resulting in a linear decrease both in absorbance and in emission, giving therefore calibration curves with a negative slope. The pyridoxamine method was successfully applied for the quantification of free chlorine from 0.2 to 250 mg/L. Using 1 cm cuvettes, the limit of quantification was 0.12 mg Cl2/L. The pyridoxamine and the DPD methods were applied to actual environmental samples, and the deviation between results was between 4% and 9%. While pyridoxamine does not react with chloramine, quantification of monochloramine was possible when iodide was added, but the reaction is unfavourably slow.

Influence Mechanism of Cyanobacterial Extracellular Polymeric Substances on the Water Quality in Dynamic Water Supply System

As a kind of high-organic-content contamination source, extracellular polymeric substances (EPS) secreted by cyanobacteria have become an important factor restricting the safety of supply water. In the dynamic batch mode water supply system, cyanobacterial EPS accelerated the decay rate of residual chlorine, resulting in a 21–26 times increase of the total viable bacteria count within 72 h. The water turbidity exceeded upper limit of the standards for drinking water quality within 4 h, with an increase of 306–332% within 72 h. The biological stability was reduced with BDOC and AOC increased by 41.4–43.8% and 331–396%, respectively. The main cause is that cyanobacterial EPS act as nutrients and metabolic energy for microorganisms, promoting their metabolic activity and secretion of extracellular organic components. This leads to the metabolic accumulation of tryptophan, fulvic acids and humic acids in the pipeline, thus further promoting the regeneration of bacteria. Compared with the influence of biofilm on pipe wall caused by long-term use of water supply network, the contribution of cyanobacterial EPS to the water contamination of pipe network is increased several times. Therefore, even in the presence of residual chlorine, the secondary contamination caused by cyanobacterial EPS in the water supply system could not be neglected.

Occurrence of Disinfection By-Products in Swimming Pools in the Area of Thessaloniki, Northern Greece. Assessment of Multi-Pathway Exposure and Risk

This study investigated the occurrence of disinfection by-products (DBPs) (trihalomethanes (THMs), haloacetic acids (HAAs), halonitriles (HANs), halonitromethane (TCNM) and haloketones (HKs)) in different type of swimming pools in the area of Thessaloniki, northern Greece by employing the EPA methods 551.1 and 552.3. Moreover, general water quality parameters (pH, residual chlorine, dissolved organic carbon, UV254 absorption, total nitrogen, alkalinity and conductivity) were also measured. The concentrations of DBPs showed great variability among swimming pools as well as within the same pool between sampling campaigns. HAAs exhibited the highest concentrations followed by THMs, HANs, TCNM and HKs. Exposure doses for four age groups (3–<6 y, 6–<11 y, 11–<16 y and adults) were calculated. Route-specific exposures varied among DBPs groups. Inhalation was the dominant exposure route to THMs and TCNM (up to 92–95%). Ingestion and dermal absorption were the main exposure routes to HAAs (40–82% and 18–59%, respectively), depending on the age of swimmers. HANs contributed up to 75% to the calculated cytotoxicity of pool water. Hazard indices for different exposure routes were <1, suggesting non-carcinogenic risk. Inhalation posed the higher carcinogenic risk for THMs, whereas risk via oral and dermal routes was low. Ingestion and dermal contact posed the higher risk for HAAs. Risk management strategies that minimise DBPs exposure without compromising disinfection efficiency in swimming pools are necessary.

Bacteriological and Physico-chemical Qualities of Halabja Drinking Water

Water is crucial for all known forms of life without providing any calories or organic nutrients, while many people, especially in developing countries, may not be able to access pure and safe drinking water. They could lose their lives or become sick because waterborne diseases could contaminate the water, and when the chemical and/or physical properties of the water are not within the national and international standards. Thus, the present study aimed to evaluate water quality of the Halabja drinking water and Sirwan river. Halabja city is located to north of Iraq, north-east of the capital Baghdad. Every week of the year 2019, apart from official holidays, water samples were collected from each of river and several areas (4-10 sections) in Halabja for the bacteriological analysis, while chemical and physical water quality was monthly checked. The results showed no detectable waterborne pathogens in all drinking water samples. Additionally, values of pH, turbidity, total dissolved substances, and electrical conductivity of the purified water samples had ranges of 7.97–8.5, 0.02-0.8 NTU, 246–362 mg/L, and 383–566 µS/cm, respectively. The treated drinking water was free of Free Residual Chlorine (FRC) and nitrite. The amounts of chloride, sulfate, and nitrate varied during the year 2019, with ranges of 48.2- 73.8, 36-141.5, and 1-5 mg/L, respectively. The values of water hardness and Ca+2 and Mg+2 concentrations ranged 132- 344, 48–89.5, and 2.2-29.2 mg/L, respectively. Based on the results, values of all the above parameters were within the Iraqi and the World Health Organization (WHO) drinking water standards, although the value of water hardness and the concentration of Ca+2 were near the upper limits of the standards, which might cause harm to the human body.

The Study of Grading Method and Application Performance of Management Systems of Rural Potable Water Treatment Plants

The application of management systems can solve the manage problems and improve the potable water safety for rural potable water treatment plants. The systems in Zhejiang province, China are studied and the system grading method is proposed as attendance management (G1), basic automatic management (G2), quantity-based automatic management (G3), quality-based intelligent management (G4), quality-based & feedback controlled intelligent management (G5). G3 to G5 systems can achieve remote control and G4, G5 systems can guarantee the finished water quality theoretically. The application performance of the management systems shows G5 system has the lowest allocated annual cost as 11500 RMB per year when used to service life as 5 years (23.37% of G1 system). By using G5 system, the finished water turbidity is below 0.8 NTU, pH is between 7.6 to 8.2, and the qualification rate of residual chlorine is above 92.5%, which performances better than G3 system with finished water turbidity below 9.7 NTU, pH between 7.3 to 8.2, and the qualification rate of residual chlorine above 88.7%. G5 system is recommended when the plant is hard to be staffed or the inlet water quality is not good. G3 system is recommended when the inlet water quality is good or the purchase budget is limited.