Use Of Wastewater Research Articles

Wastewater recycling and reuse trends in Pennsylvania shale gas wells

Thousands of shale gas wells have been drilled and hydraulically fractured across the state of Pennsylvania over the past decade, and more wells are being drilled each year. The drilled lengths of these wells and the amount of water being used to hydraulically fracture (frac) them continue to increase. These increases have led to an increase in the volume of wastewater being produced each year. However, the ratio of energy produced per barrel of wastewater has increased significantly over the past six years. Recent data show the volume of wastewater produced in one year is approximately 20% of the volume of frac water used in that same year. With changes in state policies, drilling companies in Pennsylvania have been recycling most of their wastewaters over the past few years. The development of various treatment technologies and brine-resistant frac mixtures has allowed companies to recycle this wastewater for use in future frac jobs. Use of this recycled water does not appear to be having a significant effect on production of oil or gas from wells. Recycling wastewater can be very cost-competitive when compared to options such as disposal via waste-treatment plants or injection wells.

Wastewater use in agriculture in Djibouti: Effectiveness of sand filtration treatments and impact of wastewater irrigation on growth and yield of Panicum maximum

In the arid climate of Djibouti, salt concentrations of up to 1200mgL−1 have been recorded in well water, attributed to the overexploitation of aquifers. Farmers are therefore turning to untreated wastewater as a source of water for crop irrigation. The authors undertook a study in two phases. In the first phase they tested the field transposition of an experimental water treatment method previously laboratory-tested on a small scale. The pilot device was composed of an adaptor basin for the wastewater, a filter basin filled with sand and a storage basin to collect and hold the treated water. Transfer of waters from basin to basin was gravitational. The physicochemical and microbiological sleek raw water parameters were determined weekly for 7 weeks. Monitoring of chemical oxygen demand concentrations decreased from 445±5.76mgL−1 O2 on the first day of the experiment to 101±1.34mgL−1 O2 on the 21st day. The removal of total coliforms attained more than 99.6% as of day 21. The performance of the microbiological treatment of waters obtained through sand filtration is therefore of definite interest in agriculture. In the second phase the effect of different irrigation waters (untreated wastewater (WW), treated wastewater (TW), saline well water (SW), mixed water (MW) and potable water (PW)) on growth and yield of the grass Panicum maximum were also compared. The use of WW and TW in irrigation effectively increased stem height and aerial part dry matter compared to other treatments, while irrigation with SW and PW showed the lowest measured values. Depending on their performance, the effectiveness of the treated waters can be ranked in the following increasing order: TW; WW>MW>PW; SW. The performance of the TW treatment can be explained by its higher nutritive content, especially in N.

Fertigation with Wastewater and Vermicompost: Soil Biochemical and Agronomic Implications

To study how wastewater (WW) and different organic sources (humic substances or vermicompost) affected soil chemical and biochemical fertility and agronomic productivity in field-grown melon, an experiment arranged in a randomized complete block design with three replications was conducted with the following treatments: three different mixtures of irrigation water (100% WW, 50% WW with 50% groundwater, and 100% groundwater) and, for each WW treatment, four different organic fertilization treatments of control without organic matter application (CK), vermicompost used as surface mulch (SM), vermicompost incorporated into the soil (VC), and humic substances extracted by vermicompost (HS). Chemical and biochemical results indicated an improvement in soil fertility, suggested by the increase in soil organic carbon and nutrient (nitrate and macro- and microelements) contents and in soil microbial activities (hydrolytic and oxidative enzymes), in particular in the VC treatments. In addition, even soil potential metabolism was stimulated by WW combined with organic treatments, as highlighted by the increase in the metabolic (dehydrogenase activity/watersoluble carbon) and nitrification indices (NO−3 and NH+4). Melon productivity confirmed these results, with the highest yield and melon quality in the VC treatments irrigated with 100% WW. In conclusion, the combined use of WW and organic amendment, recovering both mineral and organic nutrients from these kinds of recycled materials, was effective in the improvement of soil quality and crop productivity.

A century of water supply expansion for ten U.S. cities

As population and water demand have grown, U.S. cities have responded by expanding their water supplies. This article traces this process over a century for ten U.S. cities. Most of the cities began by providing inexpensive local ground water. As the renewable supply capacity of local sources was exceeded, cities were forced to look further afield to obtain (or purchase) water (e.g., Marion, IL; Greensboro, NC), to access water from Federal projects (Tucson, AZ) or through international or interstate agreements (Waukesha, WI and Virginia Beach, VA), to combine with other localities in large joint projects (Greensboro, NC), or to use eminent domain to annex land for a new reservoir. This last approach has become increasingly limited by environmental statutes. The purchasing of water from other systems (Greensboro, NC) or water rights ( Tucson, AZ), aquifer storage and recovery systems (Tucson, AZ, Wichita, KS), and reclaiming wastewater for use in non-potable landscaping (Alamogordo, NM; Lubbock, TX; Tucson, AZ) are the more expensive options that cities are increasingly utilizing. Desalination represents the end of this process – expensive, but with a potential for enormous supply expansion that exceeds all likely demands. Demand management measures come into play only when the cost of securing additional water begins to exceed the cost of conservation or is induced by law. Reservoirs, well-fields, desalination plants, aquifer storage and recovery systems, and inter-basin water purchases have been abandoned because of the restrictions imposed by environmental laws or because less expensive demand-side options have been identified. The relationship between city size and its progression through these increasingly expensive water supply options is determined by local water resource endowments as determined by legal considerations and its physical geographic setting.

Bioaccumulation and Translocation Efficiency of Heavy Metals in Vegetables Grown on Long-Term Wastewater Irrigated Soil Near Bindal River, Dehradun

A field study was conducted to the accumulation and translocation efficiency (TE) of heavy metals in vegetables crops grown in the wastewater (WW) irrigated agricultural soil which may be phytotoxic in their high concentrations. The study revealed that WW, being used for irrigation for various vegetable crops near Bindal river, Dehradun, contained lower concentration of Pb (0.36 ± 0.06 mg/l), Cu (0.15 ± 0.01 mg/l), Zn (0.55 ± 0.02 mg/l), Ni (0.32 ± 0.01 mg/l), Cd (0.03 ± 0.00 mg/l), and Cr (1.37 ± 0.09 mg/l) while Hg was below the detection limit (BDL). In WW irrigated soil, the concentration of Pb (70.49 ± 10.54 mg/kg), Cu (54.48 ± 9.63 mg/kg), Zn (244.15 ± 7.19 mg/kg), Ni (27.77 ± 1.50 mg/kg), and Cr (129.52 ± 9.71 mg/kg) was observed to be below than the official Indian standards except that of Cd (17.47 ± 1.20 mg/kg). These concentrations of Pb, Cu, Zn, and Ni were lower than the values reported for tolerable levels except that of Cr (129.52 mg/kg). The enrichment factor calculated for WW irrigated soil was in the order Cr (7.09) > Zn (4.09) > Cu (2.64) > Cd (2.30) > Pb (1.89) > Ni (1.50). Among various corps grown in WW irrigated soil, the maximum concentration of the metals was found in the roots of Brassica juncea (Pb, 33.62 ± 2.41 mg/kg), Phaselous vulgaris (Cu, 31.76 ± 10.92 mg/kg), B.oleracea var. botrytis (Zn, 137.32 ± 9.11 mg/kg), Ni (296.03 ± 70.98 mg/kg); Cd (36.13 ± 5.26 mg/kg); and Cr (165.94 ± 11.70 mg/kg) in P. vulgaris root and Hg was BDL. The bioaccumulation factor (BAF) of metals in vegetables from soils was higher for Pb (0.436) in B. juncea, for Cu (0.213) in P. vulgaris, for Zn (0.195) in B.juncea, for Ni (14.043) and Cd (1.349) in B.oleracea var. botrytis and for Cr (0.822) in Raphanus sativus. The TE was maximum for Pb (67.39 %), Cu (68.76 %), Zn (63.35 %), Ni (70.51 %), Cd (65.99 %), and Cr (60.20 %) in R. sativus. The study concluded that the use of WW for irrigation of crop vegetables has increased the concentration of heavy metals (Pb, Cu, Zn, Ni, Cd, and Cr) in their different parts which may pose a potential threat to human health from this long-term practice of irrigation.

Efficient and simple method for determination of suspendibility of bio-inoculant suspensions

This study assessed the utilization of viscosity and zeta potential as a novel method to evaluate suspendibility of formulation of Sinorhizobium meliloti grown in starch industry wastewater for use as bio-inoculants. For this objective, sorbitol was used as a suspending agent at concentrations of 0 to 10% w/v. Model, based on multiple linear regression (with pH as dependant variable, and zeta potential, average particle size and sorbitol concentration as independent variables) demonstrated an important relation which was significant (p<0.001, R2=0.98). Sigmoid regression revealed a significant relation between zeta potential and suspendibility with p value=0.007 and R-squared=0.86, and between viscosity and suspendibility (p value<0.0001 and R squared=0.9823). Thus, these direct correlations established the lowering of measurement time from 12h to 5min.

Effects of long‐term irrigation with treated wastewater on the hydraulic properties of a clayey soil

The increasing demand for freshwater (FW) for domestic use turns treated wastewater (WW) into an attractive source of water for irrigated agriculture. The main goal of this study was to evaluate the impact of 15 yrs of irrigation with WW on hydraulic properties and flow processes in a clayey soil, compared to FW use. It also quantitatively addressed the distribution with depth along the soil profile of that impact on soil hydraulic properties. Standard methods used in soil physics at the laboratory scale, and numerical solutions of the flow equations on the basis of HYDRUS, were applied to define fundamental soil hydraulic properties of disturbed soil samples from 0–20, 20–40, and 40–60 cm layers in the root zone. Results showed that saturated hydraulic conductivity, sorptivity, and infiltration rates are consistently lower in the WW irrigated soil samples at all depths. Water retention and hydraulic conductivity functions were affected by the use of WW, leading to a smaller, simulated‐wetted volume below a dripper for the WW‐irrigated soil case. These results illustrate the combined and complex effect of WW use on soil‐exchangeable sodium percentage, and suggest changes in contact angle and pore size distribution. They also suggest that WW application will affect differently different zones in the soil profile, depending on irrigation management parameters and plant uptake characteristics.

Current and Future Challenges for DEWATS Researchers and Designers

The current challenges facing the provision of sanitation services to the poor are explained in terms of the MDGs, rigid discharge standards, increasing water stress, intermittent energy supply are outlined. They are contrasted with future responses and objectives such as sustainability targets, risk based approaches to the setting of effluent limits, the emphasis on water conservation, food security and the acknowledgement of excreta as a resource. In spite of these secondary objective it must be noted that the primary reason for sanitation systems is public health. The main pathogen load is in excreta which is traditionally dispersed in many times its mass of water. The large numbers of peoples to be served implies that the systems need to be standardized, prefabricated and to be capable of integrating into an upgrade trajectory. This implies that although the systems must be inexpensive, the technology which is used to developing the systems must be sophisticated. The upgrade trajectory needs to take into account aspects such as low flows, separated waste streams (source separation), the beneficial use of the components in excreta (possibly in agriculture) and the use of low energy processes - possibly to be even a net energy producer. Research challenges will include the splitting of streams so as to promote better treatment or reuse; the development of low pressure (or gravity driven) membrane systems and the integration of constructed wetlands and agricultural systems into the treatment process. The streams will become much more concentrated so that reactor design more sophisticated. The DEWATS system which consisting of an anaerobic baffled reactor followed by an anaerobic filter which feeds into a constructed wetland and incorporating gravity membrane filtration will provide different qualities of treated wastewater for use in horticulture. The inclusion of source separation will provide additional cost savings and agricultural benefits.

Assessing the net benefits of using wastewater treated with a membrane bioreactor for irrigating vegetables in Crete

The island of Crete (Greece) suffers from an increasingly severe water shortages, coupled with declining groundwater supplies. We compared the costs and benefits of alternative strategies for treating wastewater for use in irrigating vegetables: (1) using a membrane bioreactor (MBR), (2) connecting new residences to centralized wastewater-treatment plants, (3) building new wastewater-treatment plants, and (4) using natural wastewater-treatment systems in rural areas. We also examined the impact of increasing water scarcity on the net benefits of treating wastewater with an MBR. As expected, the value of treated wastewater increases with increasing water scarcity. The net benefit of treating wastewater with an MBR and using the reclaimed water to irrigate vegetables ranges from about 0.02 €/m3 to 2 €/m3 as water scarcity increases. Our results should be helpful in guiding analysts in Greece and other arid countries wishing to evaluate the financial viability of alternative methods of treating wastewater for use in agriculture.

Improving the biodegradability of grain distillery wastewater for use as UASB substrate by combinations of ozonation/enzymatic pre-treatments

The effect of ozonation and enzyme combination pre-treatments on the composition of grain distillery wastewater (GDWW) was investigated. Exposure of UASB granules to these pre-treated GDWW was evaluated by determining the effect on granule activity, visual appearance and lipid content of the granules. Pre-treatments involving a pre-ozonation step were found to be more effective in reducing the lipid and COD content of GDWW. The higher the lipid and COD reduction achieved by the pre-treatments the higher the granule activity after 24 d exposure, the lower the lipid content in the granule and the less severe the formation of an encapsulating layer.

Modeling Graywater in Residences: Using Shower Effluent in the Toilet Reservoir

Use of municipal water in residences can be decreased substantially by allowing “graywater” effluent from showering and other activities to fill the toilet reservoir. This paper considers a system developed in Germany for treatment and storage of shower wastewater for use in flushing the toilet. Based on literature data for distributions of shower duration and water flow rate, the volume of municipal water saved using the German system has been estimated for several usage scenarios. Results show significant savings of water that depend on the size of the treatment and storage tanks used in the graywater system as well as the number of toilet flushes per day. For example, a scenario with four residents each flushing nine times per day with 80 liter treatment and storage tanks shows a 50% chance that the savings in municipal water use for the toilet will exceed 73%. Because the timing of showers and toilet flushes is assumed to follow a uniform distribution throughout the day, the calculated tank sizes may be underestimates.

Review of the Feasibility of Recovering Phosphate from Wastewater for Use as a Raw Material by the Phosphate Industry

Phosphate recovered from wastewater may represent an alternative source of raw material for the manufacture of phosphate products. Within wastewater treatment plants phosphate has been found to spontaneously precipitate forming crystalline deposits of a double salt of magnesium ammonium phosphate, known as struvite. Clearly the conditions for its formation can be found naturally within the environment of wastewater treatment works. The implication is that if these conditions can be exploited it may be possible for struvite to be extracted in commercially economic quantities. A literature review was undertaken to examine the precise conditions under which struvite will precipitate together with the morphology of its crystals and their settlement characteristics. For struvite to form its components must be available in at least a molecular ratio of 1(Mg2+):1(NH4 +):1(PO4 3−). Municipal wastewater is typically deficient in magnesium while ammonium is present in excess. Conditions must also be alkaline, above pH 7.5 — 8 for precipitation to occur. Dosing is therefore required to supplement the magnesium supply and raise the ambient pH. Struvite crystal cells are orthorhombic in character ranging from X - shaped to flat trapezoidal depending upon the degree of supersaturation of the solution. A qualitative economic evaluation undertaken demonstrated a number of cost savings and costs that would be incurred if struvite formation was used as a method of nutrient reduction in wastewater streams.

The non-market value of reclaimed wastewater for use in agriculture: a contingent valuation approach

The reuse of treated water for agricultural irrigation is considered a promising option in regions facing water scarcity problems and there is an increasing number of reuse projects going on in southern European countries. The aim of this paper is to estimate the non-market benefits that society attaches to the use of reclaimed wastewater for agricultural purposes, as part of the economic assessment needed to evaluate the viability of this water management option. For this purpose, a contingent valuation study has been developed in the Segura River Basin in south-eastern Spain, interviewing 352 individuals from a representative sample of the basin’s population. Results show that the use of reclaimed wastewater for irrigation has significant non-market environmental benefits (mean willingness to pay of€5.13 per month per household, which adds up to a total annual value of €23.3 million). In terms of volume, these benefits represent €0.31 m–3. Therefore, it can be concluded that the non-market benefits of using reclaimed wastewater for agriculture justify its implementation, as they overcome the average treatment costs of €0.16-0.26 m–3. Additionally, the analysis of preference heterogeneity suggests that the use of reclaimed wastewater in agriculture is more acceptable to people if they are made aware of their current payment for water sanitation. The inclusion of these non-market benefits in the overall assessment of water policy options will lead to better informed and more efficient water management decisions.