Water Quality (Engineering)

The present investigation deals with the assessment of the physico-chemical parameters andcorrelation coefficient of the Lake HussainSagar, Hyderabad, Telangana. Seasonal variations of 11 physico-chemical parameters were observed at five different sampling stations. The physico-chemical  characteristics and correlation coefficient were studied and analyzed during February 2010- October 2012.Correlation coefficient indicates showed high significant positive and negative relationship (p <0.01 level) and also show significant
positive and negative relationship (p < 0.05 level). 11 physico-chemical parameters were taken in consideration for the analysis of the lake water quality such as pH, Temperature, Total dissolved solids (TDS), Total suspended solids (TSS), dissolved oxygen(DO), Nitrates (as N), Ammonical Nitrogen (as N), Total Nitrogen, Total Phosphorus, Chemical oxygen demand(COD), Carbonaceous Biological oxygen demand(cBOD or BOD5).

This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m−2 day−1. The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.

Water deficit problem originates from two factors: population increase and water pollution. However, studying and forecasting the quality of water are necessary to avoid serious problems in future through managerial works. In present study, using time series modeling, the quality of Madian Rood River is studied at Baraftab station using time series analysis. Nine parameters of water quality are studied such as: TDS, EC, HCO 3-, Cl-, SO 4 2+ , Ca 2+ , Mg 2+ , Na + and SAR. Investigation of observed time series shows that there is a common increasing trend for all parameters unless Na + and SAR. The order of models for each parameter was determined using Auto Correlation Function (ACF) and Partial Auto Correlation Function (PACF) of time series. The ARIMA model was used to generate and forecast the quality of stream flows. Akaike Information Criterion (AIC), Determination Coefficient (R 2), Root Mean Square Error (RMSE) and (Volume Error in Percent (VE %) criteria were referred to evaluate the generation and validation results. The Results show that time series modeling is quite capable of water quality forecasting. For the majority of forecasts, the value of R 2 was greater than 0.6 between predicted and observed values.

Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m2 d1 and 3 g NO3–N m2 d1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both
ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification.
The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m2 d1) and nitrate (0.6–3.2 g NO3–N m2 d1) seem to have influenced the respective removal rates.

A research project was conducted during 2008-2009 in Portugal to evaluate the potential of reclaimed water from constructed wetlands for irrigation reuse. A 21 month monitoring campaign was set up in a Filtralite-based horizontal subsurface flow bed. Results showed a significant fluctuation of the hydraulic loading rate that has influenced the hydraulic retention time and the wastewater characteristics over time and, therefore, the removal efficiencies for BOD5, COD, TSS, nitrogen and phosphorus were lower than the reported values for CW performance. If the hydraulic loading rate could be properly controlled the treatment performance, as well as the quality of the reclaimed water, can be improved considerably. The effluent concentrations of conductivity (EC), BOD5, COD, TN, K, Ca, Mg and phytotoxic elements (Na, Cl and B), showed a suitable quality for irrigation reuse according to different international standards, although it is necessary to improve the removal of phosphorous and a final disinfection must be implemented to decrease the pathogenic content.

Oil spill in Gulf was the biggest disaster in history. The scale of damage was enormous, ranging from destruction caused by oil fires and oil spills, to economic decline for the Kuwaiti oil industry. The transport modelling of the fresh water aquifers in north Kuwait was undertaken to assess potential remediation scenarios using the MODFLOW-SURFACT numerical code. Three inter-linked models were calibrated; flow, density (salinity) and transport. The model domain is a sub-regional area encompassing the Al-Raudhatain and Umm Al-Aish Basins. The time-variant salinity transport model was calibrated simultaneously with the transient groundwater flow system and this includes variably saturated flow and transport. This was done prior to proceeding to simulate contaminant hydrocarbon transport as the hydraulic gradients and flow directions (and storage volume) are significant controls on contaminant migration. The results depicted after 23 years and with respect to the total area of the fresh water body at Al-Raudhatain (55.2 km2) and Umm Al-Aish (37 km2), the areal extent of the total petroleum hydrocarbon plume is estimated to be 7.3 km2 and 8.7 km2 for the 0.1 mg/L contour respectively. This equates to total petroleum hydrocarbon impacting 13 % and 24 % of the Al-Raudhatain and Umm Al-Aish freshwater bodies respectively. The simulation indicated that even though total petroleum hydrocarbon loading was negligible in the centre of the Al-Raudhatain depression up until recent past, what has entered the groundwater system earlier from the contamination sources (pits, fringes and lakes) is still moving towards the freshwater lenses or is potentially undetected due to lack of optimal existing monitoring bore screen and depth installations (plume diving). Implying, the environment is to be the victim of war (Gulf Crisis). The ecological and economic full impact probably will not be realized in the near future.

URL:
https://onlinelibrary.wiley.com/doi/abs/10.2175/106143016X14798353399250

Owing to low investment and maintenance costs, there has been a growing interest in applying plants in wastewater treatment. Plants commonly used in constructed wetlands (CW) include: cattail, reed, rush, yellow flag, manna grass, and willow.
In a CW, application of plants brings several benefits: creating aerobic conditions in the otherwise anaerobic rhizosphere, providing carbon compounds into the rhizosphere, uptaking pollutants (e.g. nutrients and heavy metals) from treated wastewater; improving the hydraulic conditions of wastewater flow through CW beds, and also increasing the available surface for growth of microbial biofilms. Hydrophytes also have great transpiration potential. Numerous studies have shown the importance of evapotranspiration during hot periods in natural wetlands and also in constructed wetlands. Evapotranspiration affects treatment efficiency in CWs: it increases the concentration of dissolved compounds due to decreasing water volume. Therefore, having regard to the mode of operating (VSSW or HSSW), temperature and influent characteristics (e.g. HLR and wastewater influent loads), the removal efficiency calculated as a comparison between initial and final concentration is lower, than expected from mass balance. Given results from systems in colder (Poland) and warmer (Portugal) climate conditions shows that the difference in methodology of removal efficiency calculation is significant, even if the CWs are operating in different modes. Usually, in the literature removal efficiency is expressed on the basis of concentrations, mostly due to lack of flow rate monitoring. Unfortunately, this may seriously underestimate treatment performance of CWs. This study suggests the need for routine monitoring of flow rate, or evaluation of potential evapotranspiration, to estimate removal efficiency of a CW based on mass balance.

Low pH soils with insufficient organic matter can benefit from the application of reclaimed water (RW) and biosolids. The presence of nutrients also aids plant growth. This paper presents the results of two integrated research studies, both carried out in the Beira Interior Region (Covilhã, Portugal); one used RW for irrigation, the other applied paper mill sludge to agricultural land. In both cases, multiple criteria based on GIS tools were used for site selection. In the first study, the characteristics of RW analyzed over 2 years were found suitable for crop irrigation. The RW had moderate organic content, low electrical conductivity (CE), high nutrient content (N, P), and low concentrations of nitrate, metals and phytotoxic elements (Al, B, Cl and Na). The multi-criteria analysis was carried out taking into account environmental, technical and economic criteria and a suitable area of 30.5 ha was found for RW irrigation. In the second work, the paper mill sludge was considered suitable for application to agricultural land. Its concentrations of N, P and heavy metals did not a present risk for soil contamination and were suitable for soil improvement and crop production. A multi-criteria analysis based on similar criteria was conducted and a suitable area of 253 ha was found for sludge application.