Improving the waterproofing efficiency by using a plugging compound

Increasing the efficiency of water shut-off works is one of the important tasks for the sustainable well operation. The article discusses the use of various plugging compositions for water inflow into a well isolating, their advantages and disadvantages, conditions of use, and presents the results of a study of the proposed composition. The composition of an aqueous solution of polyaluminium chloride and a suspension of gypsum anhydrite is considered. The composition contains 45-55 mass percent of 15-25 percent aqueous solution of polyaluminium chloride and 45-55 mass percent suspension of gypsum anhydrite at a water-solid ratio of 0.9. The technical result is an increase in the efficiency of water inflow into the well isolating by obtaining a homogeneous, dense plugging mass formed by mixing the components of the composition and gaining maximum strength over time. Keywords: well; water cut; isolation; water inflow; plugging mass; bottomhole formation zone; oil production; polyaluminium chloride; anhydrite.

Troubleshooting Foaming in Membrane Bioreactor: Review of Foam Analysis, Causes and Remedies

Membrane Bioreactors have proved to be a useful alternative to conventional activated sludge systems for wastewater treatment. Merits of membrane bioreactors include more compact design saving a significant amount of space and lower sludge production due to longer sludge retention time. This system unfortunately has a downside with it comes to excessive foaming. Membrane bioreactors often act as foam traps leading to overflowing, wastage of sludge and difficulty in process control. Pre-Treatment of wastewater has proven to significantly reduce foaming caused by surfactants. Generally, physical methods are considered more economical and operationally convenient compared to conventional techniques including chemical treatment and advanced techniques like biological treatment. Polyaluminium chloride as a coagulant is recommended as a chemical treatment due to economic and effectiveness considerations. It has been concluded that the remedies for foaming issue are case specific and should be determined by the causes of foaming. This paper aims at reviewing techniques to analyse the foaming phenomenon, causes of foaming and its remedies to manage or eliminate foam.

Effects of Lanthanum Modified Bentonite and Polyaluminium Chloride on the Environmental Variables in the Water and Sediment Phosphorus Form in Lake Yanglan, China

The application of lanthanum modified bentonite (Phoslock®) and polyaluminium chloride (PAC) is popular in the restoration of European temperate lakes; however, the effects of the application on the concentrations of phosphorus (P) in both the water and the sediments have been poorly evaluated to date. We studied the effects of the application of Phoslock® + PAC on the concentrations of total phosphorus (TP), particulate phosphorus (PP), soluble reactive phosphorus (SRP), total suspended solids (TSS) and chlorophyll a (Chla) in the water, and different P forms in the sediments, in an isolated part of Lake Yanglan. The results showed that the concentrations of TP, PP, SRP, TSS and Chla decreased significantly after the addition of Phoslock® + PAC. Moreover, the concentrations of labile-P, reductant-soluble-P and organic-P in the sediments were also significantly decreased after the Phoslock® + PAC application. However, the concentrations of both the stable apatite-P and residual-P in the sediments after application of Phoslock® + PAC were much higher than the pre-addition values, while the concentrations of metal-oxide-P did not differ significantly between the pre- and post- application conditions. Our findings imply that the combined application of Phoslock® and PAC can be used in the restoration of subtropical shallow lakes, to reduce the concentrations of P in the water and suppress the release of P from the sediments.

Polyaluminium chloride dosing effects on coagulation performance: case study, Barekese, Ghana

Alum, the predominant coagulant in conventional drinking water treatment schemes, has various disadvantages including the production of large volumes of sludge, lowering water pH (requiring pH adjustment using lime), limited coagulation pH range of 6.5 to 8.0, etc. At the Barekese Water Treatment Plant in Ghana, an alternative, the polyelectrolyte – Polyaluminium chloride (PAC) is also used in coagulation but limited information is available on the operating conditions required to achieve better performance than alum-based coagulation. The aim of this study was to determine the optimal coagulant dose, mixing speed and operating pH for enhanced performance in water treatment. The effects on the treatment process of three different sets of mixing speed pairs – 180/40, 180/25 and 150/25 revolutions per minute (fast/slow) – in a pH range of 6.5 to 8.0 were investigated. The mixing speed and PAC dose yielding the best coagulation were 150/25 rpm and 15 mg/L respectively. The optimal pH range for PAC coagulation performance was 7.5 to 8.0.

EFEKTIVITAS KOAGULAN TERHADAP PENURUNAN PARAMETER LIMBAH CAIR INDUSTRI TAHU

Industri tahu di Kelurahan Gunung Sulah yang dijalankan masih berskala rumah tangga dan home industri. Hingga saat ini belum dilakukan pengolahan limbah cair, baik cara fisik, kimia, maupun biologis. Peneliti bertujuan mengetahui efektifitas koagulan <em>Polyaluminium Chloride (PAC)</em> dalam pengolahan limbah cair industri tahu. Eksperimen menggunakan rancangan <em>Pretest-Posttest</em> <em>With Control Grup. </em>Sampel penelitian diambil dari sentra industri tahu di Kelurahan Gunung Sulah, Kota bandar Lampung. Dosis PAC terdiri dari empat level (75, 150, 225, 300 mg/l), demikian pula pada waktu pengadukan (10, 15, 20, 25 menit). Parameter yang diamatai adalah COD dan TSS. Analisis statistik menggunakan uji Kruskal-Wallis. Pemeriksaan dilakukan pada Bulan Mei 2017 di Laboratorium Terpadu Politeknik Kesehatan Tanjungkarang. Hasil uji statistik menunjukkan dosis PAC yang efektif untuk menurunkan nilai COD dan TSS adalah 300mg/l. Waktu pengadukan lambat yang efektif untuk menurunkan nilai COD dan TSS adalah 25 menit. PAC dapat diterapkan dalam limbah industry dengan mengontrol pH agar tidak mencemari lingkungan.

Application of Polyaluminium Chloride Coagulant in Urban River Water Treatment Influenced the Microbial Community in River Sediment

Polyaluminium chloride (PAC) has been widely used as a chemical coagulant in water treatment. However, little is known about the impact of PAC performance on the microbial community in sediments. In this study, the archaeal, bacterial, and fungal communities in urban river sediments with and without PAC treatment were investigated. Prokaryotic diversity decreased at the PAC addition site (A2) and increased along with the river flow (from A3 to A4), while eukaryotic diversity was the opposite. The abundance of core microbiota showed a similar trend. For example, the dominant Proteobacteria presented the highest relative abundance in A1 (26.8%) and the lowest in A2 (15.3%), followed by A3 (17.5%) and A4 (23.0%). In contrast, Rozellomycota was more dominant in A2 (56.6%) and A3 (58.1%) than in A1 (6.2%) and A4 (16.3%). Salinity, total dissolved solids, and metal contents were identified as the key physicochemical factors affecting the assembly of core microorganisms. The predicted functions of archaea and fungi were mainly divided into methane cycling and saprotrophic nutrition, respectively, while bacterial function was more diversified. The above findings are helpful to enhance our understanding of microorganism response to PAC and have significance for water treatment within the framework of microecology.

‘Floc and Sink’ Technique Removes Cyanobacteria and Microcystins from Tropical Reservoir Water

Combining coagulants with ballast (natural soil or modified clay) to remove cyanobacteria from the water column is a promising tool to mitigate nuisance blooms. Nevertheless, the possible effects of this technique on different toxin-producing cyanobacteria species have not been thoroughly investigated. This laboratory study evaluated the potential effects of the “Floc and Sink” technique on releasing microcystins (MC) from the precipitated biomass. A combined treatment of polyaluminium chloride (PAC) with lanthanum modified bentonite (LMB) and/or local red soil (LRS) was applied to the bloom material (mainly Dolichospermum circinalis and Microcystis aeruginosa) of a tropical reservoir. Intra and extracellular MC and biomass removal were evaluated. PAC alone was not efficient to remove the biomass, while PAC + LMB + LRS was the most efficient and removed 4.3–7.5 times more biomass than other treatments. Intracellular MC concentrations ranged between 12 and 2.180 µg L−1 independent from the biomass. PAC treatment increased extracellular MC concentrations from 3.5 to 6 times. However, when combined with ballast, extracellular MC was up to 4.2 times lower in the top of the test tubes. Nevertheless, PAC + LRS and PAC + LMB + LRS treatments showed extracellular MC concentration eight times higher than controls in the bottom. Our results showed that Floc and Sink appears to be more promising in removing cyanobacteria and extracellular MC from the water column than a sole coagulant (PAC).

Phosphorus in the shallow, urban lake subjected to restoration - case study of Lake Domowe Duże in Szczytno

The paper presents the results of the research on the restoration of the shallow Lake Domowe Duże in Szczytno (area 0.6 km2, average depth 3.4m). Restoration treatments were carried out in the years 2010-2012 and consisted in the inactivation of phosphorus using polyaluminium chloride. Technical restoration was supported by biomanipulation treatments consisting in stocking the lake with predatory fish. Water quality study were carried out before remediation and annually for a decade (2010-2019) during and after the application of coagulant. It was shown that the efficiency of removing excess phosphorus from water column was high (decrease from 0.23 mgP L-1 to 0.05 mgP L-1). The effects achieved during the coagulant application were maintained for 5 years after the end of the project. Currently, the phosphorus pool is still twice as low as before the treatments, but it is gradually increasing. The main external factor limiting permanent improvement of water quality is the open hydrological system and transport of biogenic matter by surface inflows draining anthropogenically transformed areas. Maintaining permanent improvement of water quality will require continuation of restoration measures.