Application of alternative carriers without protected surface in moving bed biofilm reactor for domestic wastewater treatment

Biological reactors with immobilized biomass on free carriers have provided new perspectives for wastewater treatment, once they reduce the system size and increase the treatment capacity. In this study, the performance of three Moving Bed Biofilm Reactors (MBBR) using different carriers (with and without protected surface area) were evaluated for domestic wastewater treatment in continuous flow. Each MBBRs (i.e., R1, R2, and R3) was filled at a ratio of 50% with high-density polyethylene carriers with different characteristics: both R1-K1 and R2-Corrugated tube with protected surface and R3-HDPE flakes without protected surface. Chemical oxygen demand (COD) removal of 80 ± 5.0, 80 ± 3.5, and 78 ± 2.4% was achieved by R1, R2, and R3, respectively. The oxygen uptake by biofilm attached on the carriers was 0.0079 ± 0.0013, 0.0033 ± 0.0015, and 0.0031 ± 0.0026 μg DO·mm−2 for the K1, corrugated tube, and HDPE flakes, respectively. No significant differences were observed between the performance of the three MBBRs in terms of physico-chemical parameters (alkalinity, pH, and dissolved inorganic carbon) and COD removal. Results showed that the carrier type and its characteristics (total area and with/without protected area) did not affect the organic matter removal. Thus, the carrier without a protected surface in MBBR could be a promising low-cost option for domestic wastewater treatment.

Pumping test analysis for assessment of hydraulic parameters and aquifer system formation in hilly terrain

Groundwater conditions (GWCs) of an area depends on aquifer hydraulic parameters such as storativity () or storage coefficient (), transmissivity () and hydraulic conductivity (). It plays a key role concerning- groundwater flow modeling, well performance, solute and contaminants transports assessment and also for identification of areas for additional hydrologic testing. Specifically, the geologic formation of a regions control the porosity and permeability, however, in hilly terrain prospecting ground water potential is more challenging due to its limited extent and its occurrences that are usually confined to fractures and weathered rocks. The present study, aims at estimating the hydraulic parameters through pumping test analysis to assess aquifer system formation on hilly terrain from 16 bore wells. The aforesaid parameters were examined through a case study in some selective regions of Hamirpur district of Himachal Pradesh, India. The study area is controlled under two main geological horizons that is the post-tertiary and tertiary. The papers end with comparative results of hydraulic parameters and the aquifers system formation on different GWCs which may be helpful in the outlook of sustainable groundwater resource in the regions.

Treatment of industrial electroplating wastewater for metals removal via electrocoagulation continous flow reactors

A real industrial electroplating rinsing wastewater was collected and subjected the physical and chemical examination. The study showed that it can be categorized as high strength wastewater, at pH- 2, COD 1430 mg/l, and high level of metals above permissible limits namely: 150, 30, 25, and 2.9 for Ni, Cu, Zn, and Fe mg/l respectively. Therefore, metals must be adequately removed before discharging to avoid any hazardous impact on the environment. Similar synthetic wastewater was prepared to study effect of chemical coagulation for the precipitation of metals. The optimum removal rate was achieved by using a combination of lime and ferric chloride at 100 and 30 mg/l respectively. The chemically treated electroplating wastewater was subjected to an electrocoagulation study. A comparison between iron and stainless-steel electrodes for the removal of metals was investigated. Furthermore, the effect of different electric voltage, and the contact time on metals removal efficiency were also examined. It was found that the optimum removal capacity was achieved when stainless steel electrode was employed in the presence of ferric chloride as coagulant, at 10 volts, 30 min. contact time, and pH 9 for synthetic solution. In a batch treatment system, the real industrial wastewater was treated at the predetermined optimum operating conditions; the removal of metals was 92.1%, 87.8% and 82.9% for Ni. Zn, and Cu respectively. By employing a continuous flow reactor for the treatment of the same real wastewater and under the same operating conditions; metals removal rate increased to 98.9%, 97.4% and 96.6% for Ni. Zn, and Cu respectively. The level of metals in the final treated wastewater copes with Egyptian Environmental Regulation. The overall results confirmed that the electro-coagulation (EC) technology offers an effective alternative process in combination with the conventional chemical coagulation process for reaching high removal performance of toxic metals from the electroplating wastewater. The advantage of EC technique is achieving high treatment efficiency instead of expensive chemical reagents, high construction cost and/or other conventional processes. In addition, the final treated water can be reused for rinsing process in electroplating industry and/or discharging without any environmental hazard effect. It is also recommended to employ solar energy instead of electricity to reduce cost of operation.

Bentonite blended with bagasse ash as an adsorbent for reactive red 198 dyes

Adsorption offers efficient, cost-effective, and eco-friendly method for the treatment of dye-laden wastewater. This work presents, reactive red 198 (RR198) removal by adsorption using bentonite clay (BC) blended with sugar cane bagasse ash (SCBA). The adsorbent's surface morphologies, crystalline phase structures, functional groups, and specific surface before and after adsorption were examined using SEM, XRD, FTIR, and BET respectively. Central composite design (CCD) under response surface methodology (RSM) was applied to optimize independent and dependent variable values. The optimal parameters for RR198 removal using the blended adsorbent were 107 minutes contact time, 0.934 g/L adsorbent dose, and 15 mg/L initial dye concentration, and 85.2% RR198 removal efficiency was achieved. The sorption isotherms and kinetics were evaluated using various existing models. The Freundlich isotherm model (R2 = 0.95) and the pseudo-second-order equation best described the adsorption parameters and the RR198 adsorption kinetic mechanism, respectively. Desorption and reusability experiments in batch study confirmed that BC blended with SCBA can be used multiple times for dye removal from wastewater.

Photocatalytic degradation of caffeine in a slurry reactor with intermittent UV irradiation: optimization and response surface modelling

This study focusses on the photocatalytic degradation of caffeine (CAF) a stimulating drug and environmental contaminant that pose threat to humans and the environment. The effect of operating parameters such as; CAF initial concentration (5–20 mg/L), catalyst dosage (0.1–0.9 g/L) and pH (3.0–9.0) were explored in detail. The experimental results showed the maximum CAF and chemical oxygen demand (COD) removals of 87.2% and 66.7% respectively. The optimized parameters were; CAF initial concentration – 5 mg/L, catalyst dosage – 0.5 g/L and pH – 7.2. The photocatalytic degradation of CAF followed pseudo-first order kinetics. The obtained experimental data were analysed with response surface methodology (RSM) using Design Expert Software.

Chihuahua-Sacramento and tabalaopa-aldama aquifers of Chihuahua state, Mexico: linkage and importance of geostatistical and hydrogeochemical analysis

The objective of this study is to gather sufficient information to make a diagnosis of drinking water sufficiency in the Chihuahua-Sacramento and Tabalaopa-Aldama aquifers. By applying advanced statistical techniques, the goal is to find the variables that control the regional and intermediate flow systems and establish the characteristics of a heterogeneous aquifer. The variables chosen from those established were as follows: total solids (TS), nitrates (NO3), fluoride (F), and total hardness, among others. In order to establish a conceptual model, the results from all the sampling were carried out by the National Water Commission (CONAGUA) in the aforementioned aquifers and were used to obtain an approximate flow differentiation. The results showed a good flow differentiation. In addition, a group of mixed water was detected among the intermediate and regional flows. The increase in the average regional flow values suggests a rise in the incidence of an upward flow of the regional flow as a result of uncontrolled extraction.

Process simulation of modelled reverse osmosis for desalination of seawater

Model equations for prediction of process parameters of reverse osmosis for desalination of seawater were developed via mathematical derivation from basic equations for reverse osmosis process. A model equation relating the interfacial solute concentration () with the process pressure difference () was developed. Taking the of a reverse osmosis as the basic independent variable, further model equations relating other process parameters such as the solute concentration polarity , water flux , osmotic pressure , water output rate (q), power density (Pd) and specific energy consumption (SEC) were developed. Simulation of a hypothetical reverse osmosis data using Microsoft Excel Worksheet and a Microsoft Windows 10 on a 64-bit operating system was carried out. Simulation results showed that the optimum fluid bulk concentration was = 0.0004 mole/cm3. The optimum rate of increase in the solute rejection factor per unit rise in ΔP was 0.45%. The optimum solute rejection factor was 97.6%. The optimum water output rate, specific energy consumption and power density were 103.2 L/h, 3.65 kWh/m3 and 6.09 W/m2, respectively.

Evaluation of calcium-fortified municipal water as a public health intervention to mitigate lead burdens

Lead has adverse effects on health, society, and the economy. Lead exposure results in increased blood lead levels and storage in bones. Calcium and lead are competitively absorbed and as such calcium can be used to mitigate the body lead burden. Twenty-eight quantitative research studies were reviewed that examined lead exposure (in blood, bone, or breastmilk) and calcium intake or serum calcium to evaluate the efficacy and safety of fortifying potable water supplies with calcium to mitigate lead absorption or resorption. Eighteen of the studies reported a significant inverse relationship between biomarker lead levels and calcium intake or serum calcium. The relationship was most evident with high calcium intake, suggesting a dose-dependent relationship. An intervention with calcium-fortified water could offer an accessible source of supplemental calcium to help meet the recommended dietary allowance (RDA) and mitigate lead absorption. A concentration of 60 mg-Ca/L can supply 22.0 and 16.3% of a 1,000 mg-Ca RDA for men and women, respectively, at the recommended daily water intake.

Impact of active night population and leakage exponent on leakage estimation in developing countries

Methods for network leakage estimation include water balance, component analysis and minimum night flow (MNF) methods the latter of which involves subtracting the customer night use (QCNU) from night leakage and multiplying by the hour day factor (HDF). QCNU and HDF respectively depend on Active Night Population (ANP) and leakage exponent (N1). In most developing countries, these parameters are assumed in the MNF method thus introducing errors which makes setting realistic leakage reduction targets and key performance indicators (KPI) problematic. In this study, QCNU and HDF were evaluated by determining the relative error associated with ANP and N1 to establish localized rates for accurately estimating leakage in water networks. Between 7 and 11% relative error was associated with every 1% higher or lower ANP while up to 4% relative error was observed for every step considered. A linear relationship exists between the relative error associated with both and ANP although that of ANP is twice as high as This has technical implications on setting water loss reduction targets and investing in the water infrastructure. It is recommended that water utilities must establish localized ANP and values for accurate leakage estimation in water networks.

Coagulation performance evaluation of alginate as a natural coagulant for the treatment of turbid water

Alginates are quite abundant in nature as they occur both as a structural component in marine brown algae (Phaeophyceae) comprising up to 40% of dry matter and as capsular polysaccharides in soil bacteria. Alginic acid is the only polysaccharide, which naturally contains carboxyl groups in each constituent residue, and possesses various abilities for functional materials. Experiments were carried out for the water of turbidity 300 NTU. Alginate as such doesn't act as a coagulant instead it should be converted to calcium alginate by adding calcium ions. Calcium chloride was used for imparting calcium ions necessary for the reaction. The dosage of calcium was fixed as 50 mg/L, 75 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, and alginate doses between 2 to 10 mg/L. Calcium dosage below 50 mg/L was not sufficient enough for the formation of egg-box structure which is responsible for the coagulation and flocculation process. For the mechanism of charge neutralization to take place effectively, calcium should be added first followed by alginate. pH and conductivity of the sample remain constant before and after the treatment. The dosage of alginate required for the treatment is less so the cost of treatment also will be very less, thus alginate can replace the usage of chemical coagulants like alum.