On-site treatment of flowback and produced water from shale gas hydraulic fracturing: A review and economic evaluation.

On-site flowback treatment systems are typically rated and selected based on three fundamental categories: satisfying customer needs (e.g. meeting effluent quality, capacity, delivery time and time required to reach stable and steady effluent quality), common features comparison (e.g. treatment costs, stability of operation, scalability, logistics, and maintenance frequency) and through substantial product differentiation such as better service condition, overcoming current market limitations (e.g. fouling, salinity limit), and having lower environmental footprints and emissions. For treatment of flowback, multiple on-site treatment systems are available for primary separation (i.e. reducing TSS concentrations and particle size below 25 µm for disposal), secondary separation (i.e. removing TSS, iron and main scaling ions, and reducing particle size up to 5 µm for reuse), or tertiary treatment (i.e. reducing TDS concentration in the permeate/distillate to below 500 mg/L) for recycling or discharge. Depending on geographic features, frac-fluid characteristics, and regulatory aspects, operators may choose disposal or reuse of flowback water. Among these approaches, desalination is the least utilized option while in the majority of cases on-site basic separation is selected which can result in savings up to $306,800 per well. Compared to desalination systems, basic separation systems (e.g. electrocoagulation, dissolved air floatation) have higher treatment capacity (159-4133 m3/d) and specific water treatment production per occupied space (8.9-58.8 m3/m2), lower treatment costs ($2.90 to $13.30 per m3) and energy demand, and finally generate less waste owing to their high recovery of 98-99.5%, which reduces both operator costs and environmental burdens.

Removal of inert COD and trace metals from stabilized landfill leachate by granular activated carbon (GAC) adsorption.

Landfills in Germany are currently approaching stabilization phase; as a result removal of inert organics and potentially toxic elements in the leachate is becoming a primary concern. Dissolved air floatation (DAF) at the secondary stage reduces only 27% of the residual chemical oxygen demand (COD) in the investigated treatment systems; downstream granular activated carbon (GAC) units are required to further reduce COD concentration by 40-56% to meet indirect discharge or direct discharge limits respectively. Therefore, in this study performance in terms of COD and trace metals adsorption of different types of granular activated carbon were compared over different contact times and dosages. GAC 1 with Brunauer-Emmett-Teller (BET) surface area of 719.5 ±â€¯2.1 m2/g and average pore diameter (D) of 4.81 nm was identified to be inappropriate for treatment of leachate from this landfill. GAC 2 (with BET of 1513.7 ±â€¯6.4 m2/g and D of 3.50 nm) was feasible for COD reduction from DAF-pretreated leachate, while GAC 3 (with BET of 644.5 ±â€¯2.6 m2/g and D of 5.65 nm) can be coupled either with biological step alone, or as a tertiary step after the DAF unit. Moreover, as COD is the primary remaining contaminant of interest after secondary and tertiary treatment, spectrometer probes provide a close estimation of COD concentration for use in online monitoring. Beside COD removal, GAC 3 also confirmed the effectiveness of trace metals adsorption even at trace level, as it removed 66, 64, 48, 47, 43, and 25% of copper, cobalt, chromium, manganese, nickel, and zinc, respectively.

High-rate anaerobic treatment of wastewater from soft drink industry: Methods, performance and experiences.

At an Austrian soft drink company, an expanded granular sludge bed reactor for anaerobic wastewater treatment was inoculated with sludge from paper and food industries. Detailed online monitoring and laboratory examinations were carried out during startup and subsequent phases, which included a period of inhibition after ca. 80 days during which reactor degradative performance diminished suddenly, following a period of increased effluent VFA. After dosing iron chloride (FeCl2) and micronutrients and reducing organic loading to startup levels, the reactor eventually reached efficient operation (>85% COD degradation) after a gradual recovery phase. In this work performance data both at lab and full scale are elaborated along startup, adaptation, pre-inhibition, recovery and stable phases, and correlated between scales. High rate anaerobic treatment of soft drink industry wastewater was successful in terms of COD removal efficiency and final effluent COD (∼300 mg l-1), with a startup period (including inhibition) of ca. 5 months.

Municipal landfill leachate characteristics and feasibility of retrofitting existing treatment systems with deammonification - A full scale survey.

Leachate characteristics, applied technologies and energy demand for leachate treatment were investigated through survey in different states of Germany. Based on statistical analysis of leachate quality data from 2010 to 2015, almost half of the contaminants in raw leachate satisfy direct discharge limits. Decrease in leachate pollution index of current landfills is mainly related to reduction in concentrations of certain heavy metals (Pb, Zn, Cd, Hg) and organics (biological oxygen demand (BOD5), chemical oxygen demand (COD), and adsorbable organic halogen (AOX)). However, contaminants of concern remain COD, ammonium-nitrogen (NH4N) and BOD5 with average concentrations in leachate of about 1850, 640, and 120 mg/L respectively. Concentrations of COD and NH4N vary seasonally, mainly due to temperature changes; concentrations during the first quarter of the year are mostly below the annual average value. Electrical conductivity (EC) of leachate may be used as a time and cost saving alternative to monitor sudden changes in concentration of these two parameters, due to high correlations of around 0.8 with both COD and NH4N values which are possibly due to low heavy metal concentrations in leachate. The decreased concentrations of heavy metals and BOD5 favor the retrofitting of an existing biological reactor (nitrification/denitrification) with the deammonification process and post denitrification, as this lowers average annual operational cost (in terms of energy and external carbon source) and CO2 emission by €25,850 and 15,855 kg CO2,eq respectively.