Reuse of Flowback Water from Hydraulic Fracturing for Drilling Mud Preparation and Secondary Hydrocarbon Recovery

Flowback water after completion of hydraulic fracturing is one of major waste streams generated during the lifespan of a well so its beneficial reuse is crucial. The application of treated flowback is not limited to stimulation processes but also may include drilling operations and secondary oil recovery. The flowback water used in this work is characterized by high salinity reaching up to ~295 g/L caused mainly by NaCl. The presence of suspended solids, mainly corrosion products, prompts the use of coagulation and filtration as treatment methods. Among tested coagulants the most effective one was the SAX18 (NaAlO2) commercial coagulant applied at concentration of 12 mL/L which reduces the water turbidity from over 400 FTU to 23 FTU. The applied treatment greatly reduces the concentration of scaling ions and so the concentration of SiO2 is reduced by 64%, Ba2+–66%, Fe2–36%, Mn2+–65%, SO42−–66%. The treated flowback fluid can be reused in surfactant flooding for enhanced oil recovery where achieves 7% higher displacing efficiency than fresh water. The drilling muds which were prepared using the untreated flowback water exhibit good rheological properties. The obtained results show that recycling of flowback water in future drilling and exploitation operations is technically feasible.

Beneficial Use of Water Treatment Sludge in Geotechnical Applications as a Sustainable Alternative to Preserve Natural Soils

This paper explores the feasibility of employing drinking water treatment sludge (WTS) mixed with soils, lime, or rock powder in geotechnical applications, as well as discusses the sustainability of the approach based on experimental results, aiming at the beneficial reuse of waste and the preservation of natural geomaterials. The selected materials were two soils largely used in earthworks, two WTSs, a high purity calcium hydrated lime, and rock powder from a granitic–gneissic quarry, all occurring in São Paulo State, Brazil. The mixtures were chemically, mineralogically, and geotechnically characterized, and the geotechnical properties permeability, shear strength, and deformability were investigated. Soil-WTS mixtures showed hydraulic conductivity (10−10–10−6 m/s, depending on soil and WTS), effective cohesion (10–30 kPa), friction angle (34°–40°), undrained strength (>50 kPa), and compression index (0.1–0.4) compatible with those of soils usually employed in earthworks. Lime:WTS and rock powder:WTS mixtures achieved 50 kPa undrained strength for WTS contents lower than 24% and 8%, respectively, and could be used as daily and intermediate covers of waste landfills, as well as in other applications with low soliciting stresses. The possibility of WTS being pumped instead of transported by trucks was analyzed in the light of results from rheological tests.

Amplified Impact of Climate Change on Fine-Sediment Delivery to a Subsiding Coast, Humboldt Bay, California

In Humboldt Bay, tectonic subsidence exacerbates sea-level rise (SLR). To build surface elevations and to keep pace with SLR, the sediment demand created by subsidence and SLR must be balanced by an adequate sediment supply. This study used an ensemble of plausible future scenarios to predict potential climate change impacts on suspended-sediment discharge (Qss) from fluvial sources. Streamflow was simulated using a deterministic water-balance model, and Qss was computed using statistical sediment-transport models. Changes relative to a baseline period (1981–2010) were used to assess climate impacts. For local basins that discharge directly to the bay, the ensemble means projected increases in Qss of 27% for the mid-century (2040–2069) and 58% for the end-of-century (2070–2099). For the Eel River, a regional sediment source that discharges sediment-laden plumes to the coastal margin, the ensemble means projected increases in Qss of 53% for the mid-century and 99% for the end-of-century. Climate projections of increased precipitation and streamflow produced amplified increases in the regional sediment supply that may partially or wholly mitigate sediment demand caused by the combined effects of subsidence and SLR. This finding has important implications for coastal resiliency. Coastal regions with an increasing sediment supply may be more resilient to SLR. In a broader context, an increasing sediment supply from fluvial sources has global relevance for communities threatened by SLR that are increasingly building resiliency to SLR using sediment-based solutions that include regional sediment management, beneficial reuse strategies, and marsh restoration.

Review and decision support of options for the removal, treatment and disposal of stormwater sediments

Stormwater management (SWM) ponds are a widely used option to control runoff, decrease flooding potential, reduce erosion rates in receiving waters and improve water quality. Although dredging and disposal are accepted practices, there is a need to consider alternative removal techniques, since 1) overall costs for a single pond can be substantial, and 2) a large number of ponds are approaching their operational capacity. It is evident that numerous remedial and beneficial reuse options are more economically viable and environmentally stable than current options. The intent of the current research was to develop guidance for municipalities and operators when faced with contaminated stormwater sediments. This paper presents a review of potential removal, treatment, disposal and beneficial use options and offers a simple decision support methodology to aid in the selection of options.

Review and decision support of options for the removal, treatment and disposal of stormwater sediments

Stormwater management (SWM) ponds are a widely used option to control runoff, decrease flooding potential, reduce erosion rates in receiving waters and improve water quality. Although dredging and disposal are accepted practices, there is a need to consider alternative removal techniques, since 1) overall costs for a single pond can be substantial, and 2) a large number of ponds are approaching their operational capacity. It is evident that numerous remedial and beneficial reuse options are more economically viable and environmentally stable than current options. The intent of the current research was to develop guidance for municipalities and operators when faced with contaminated stormwater sediments. This paper presents a review of potential removal, treatment, disposal and beneficial use options and offers a simple decision support methodology to aid in the selection of options.

The use of Dredged Marine Sediment in the Formulation of Air-foamed Concrete

A large quantity of sediments is dredged continuously worldwide. They are generally dumped in landfill areas which ensue in the increasing cost of the dredging operations and in soil-groundwater pollution. The objective of this work is to study the beneficial reuse of dredged sediments in foam mortar and particularly by studying the influence of the substitution of sand by dredged sediments. Air foam mortars/concrtes is an alternative to ordinary concrete, which presents the advantages of lightweight and low thermal conductivity. In this study, the density required ranges from 1200kg/m3 to 1600kg/m3 to the development of foam concrete building blocks and slabs for load-bearing and non-load-bearing structures. Twenty foam mortar mixes were prepared. Sediments were introduced by replacing 15%, 30%, and 50% mass of the sand. The foam percentage was introduced from 0–100% volume of mortar. Workability, compressive strength, and flexural strength at the age of 7, 28, and 60 days were monitored. The size distribution of foam bubbles and the effect of sediments on their stability is also studied. The results demonstrate that sediment has a good general effect on foam concrete and this opens up very promising new types of concretes. However, for a high substitution rate, a decrease in performances is denoted.

Application of Alum Sludge in Wastewater Treatment Processes: “Science” of Reuse and Reclamation Pathways

Alum sludge (AlS) refers to the inevitable by-product generated during the drinking water purification process, where Al-salt is used as a coagulant in the water industry. It has long been treated as “waste”, while landfill is its major final disposal destination. In fact, AlS is an underutilized material with huge potential for beneficial reuse as a raw material in various wastewater treatment processes. In the last two decades, intensive studies have been conducted worldwide to explore the “science” and practical application of AlS. This paper focuses on the recent developments in the use of AlS that show its strong potential for reuse in wastewater treatment processes. In particular, the review covers the key “science” of the nature and mechanisms of AlS, revealing why AlS has the potential to be a value-added material. In addition, the future focus of research towards the widespread application of AlS as a raw material/product in commercial markets is suggested, which expands the scope for AlS research and development.

Oil & gas produced water retention ponds as potential passive treatment for radium removal and beneficial reuse

Oil and gas extraction generates large volumes of produced water (PW) in regions that are water-stressed. PW can be passively treated in retention ponds prior to beneficial use. Oxic conditions lead to sequestration and lower bioavailability of Ra.

Decentralised, small-scale coagulation-membrane treatment of wastewater from metal recycling villages – a case study from Vietnam

Effective treatment of wastewaters laden with heavy metals is critical to the sustainable social and economic growth of metal recycling villages in Vietnam. Currently, most wastewaters from metal recycling villages in Vietnam are directly discharged, posing great threats to the environment and human health. In this study, a small-scale combined coagulation-membrane filtration treatment of wastewater collected from a metal recycling village in Vietnam was experimentally investigated. The experimental results manifested the technical viability of the combined coagulation-membrane filtration process for the treatment of the heavily polluted metal recycling wastewater for beneficial reuse. In this combined treatment process, coagulation using ferric chloride (FeCl2) served as a pre-treatment prior to the microfiltration (MF)/reverse osmosis (RO) process. Under the optimised conditions, coagulation at the dosage of 0.2 g FeCl2 per 1,000 ml wastewater removed more than 90% of heavy metals (i.e. most notably including aluminium and chromium) from the wastewater, reducing the aluminium and chromium concentrations in the wastewater from 548.0 to 52.3 mg/L to 32.6 and 1.7 mg/L, respectively. The MF treatment of the wastewater following the coagulation further removed suspended solids and organic matters, rendering the wastewater safe for the subsequent RO filtration with respect to membrane fouling. Given the efficient pre-treatment of coagulation and MF, the RO process at the controlled water recovery of 50% was able to effectively treat the wastewater to potable water.