Turbidity In Terms Research Articles

Bessel-Beam Interferometry for Turbidity With Refractive Index, Attenuation Coefficient, and Loss

This letter demonstrates a quasi-Bessel beam optical interferometry and fast Fourier transform (FFT) to estimate turbidity of liquid samples in terms of the refractive index (RI), optical attenuation coefficient, and loss. The device comprises a broadband superluminescent diode (SLD) source and a packaged deep-seated optical fiber negative axicon (DSNA) probe connected to the SLD source guiding light to the liquid sample trapped in between DSNA probe head and a glass slide. It generates a low-coherence interference spectrum as recorded in a spectrometer via an optical circulator. The FFT of the said spectrum gives power spectrum corresponding to the respective interfaces of the trapped sample. The power spectrum is used wisely to estimate turbidity in terms of RI, optical attenuation, and optical loss. The design is able to measure as low as 5 NTU (nephelometric turbidity units). This sensing platform may be useful in environmental protection, pharma, and processing industries.

Removal of Anionic Surfactant from Residential Laundry Wastewater using Jackfruit (Artocarpus heterophyllus) seeds

The study presented in this article investigated the removal of a long chain anionic surfactant from residential laundry wastewater using jackfruit (Artocarpus heterophyllus) seeds. The main ingredients of laundry wastewater are the surfactants. Therefore, great attention should be given to the treatment and disposal of laundry wastewater. The use of natural substitutes in treating wastewater has no harmful effects, and it is considered an effective step towards protecting the environment and promoting sustainability. Jar test experiments were conducted in order to determine the optimum conditions for the removal of surfactants, chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity in terms of effective dosage, and pH control. The surfactant, COD, BOD, and turbidity removal efficiencies were 91.66%, 82.86%, 77.66%, and 85.14% at the optimum initial pH value of 6, the optimum dose of 2.5 g/L, and optimum mixing time of 25 minutes, respectively. It can be concluded that Artocarpus heterophyllus seed powder was a feasible and cost-effective natural coagulant for the removal of anionic surfactant from laundry wastewater. The results showed that the pseudo-second-order equation is the suitable model for this system.

Review of Long Term Turbidity Trends with Possible Reasons around the World

Review of Long Term Turbidity Trends with Possible Reasons around the World

Comparison of Long Term Turbidity Trends in Different Locations

Comparison of Long Term Turbidity Trends in Different Locations

Assessment of satellite ocean color products of MERIS, MODIS and SeaWiFS along the East China Coast (in the Yellow Sea and East China Sea)

The validation of satellite ocean-color products is an important task of ocean-color missions. The uncertainties of these products are poorly quantified in the Yellow Sea (YS) and East China Sea (ECS), which are well known for their optical complexity and turbidity in terms of both oceanic and atmospheric optical properties. The objective of this paper is to evaluate the primary ocean-color products from three major ocean-color satellites, namely the Moderate Resolution Imaging Spectroradiometer (MODIS), Medium Resolution Imaging Spectrometer (MERIS), and Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Through match-up analysis with in situ data, it is found that satellite retrievals of the spectral remote sensing reflectance Rrs(λ) at the blue-green and green bands from MERIS, MODIS and SeaWiFS have the lowest uncertainties with a median of the absolute percentage of difference (APDm) of 15–27% and root-mean-square-error (RMS) of 0.0021–0.0039sr−1, whereas the Rrs(λ) uncertainty at 412nm is the highest (APDm 47–62%, RMS 0.0027–0.0041sr−1). The uncertainties of the aerosol optical thickness (AOT) τa, diffuse attenuation coefficient for downward irradiance at 490nm Kd(490), concentrations of suspended particulate sediment concentration (SPM) and Chlorophyll a (Chl-a) were also quantified. It is demonstrated that with appropriate in-water algorithms specifically developed for turbid waters rather than the standard ones adopted in the operational satellite data processing chain, the uncertainties of satellite-derived properties of Kd(490), SPM, and Chl-a may decrease significantly to the level of 20–30%, which is true for the majority of the study area. This validation activity advocates for (1) the improvement of the atmosphere correction algorithms with the regional aerosol optical model, (2) switching to regional in-water algorithms over turbid coastal waters, and (3) continuous support of the dedicated in situ data collection effort for the validation task.

Design, Analysis, and Realization of a Turbidity Sensor Based on Collection of Scattered Light by a Fiber-Optic Probe

We propose a method for sensing the turbidity of a solution using a fiber-optic bundle probe in conjunction with a mirror. We have estimated turbidity in terms of total interaction coefficient, a parameter that contains strong signature of the turbidity of a liquid. A simple model based on geometrical optics and also a light-scattering model based on Monte Carlo simulations are employed to estimate the power collected by the optical fiber probe. The method is simple, and should be useful for detecting suspended impurities in a liquid even in small quantities.

Stratigraphic controls on water quality at coal mines in southern New Zealand

Water quality at four coal mines in southern New Zealand can be related directly or indirectly to the geology and mineralogy of the stratigraphic sequence in which the coal mines occur. The Late Cretaceous Taratu Formation of the Kaitangata coalfield formed in a marginal marine setting during regional marine transgression, and marine incursions punctuated coal formation. Abundant authigenic and remobilised pyrite at the Wangaloa mine (typically 4 wt%S in coal) in the Kaitangata coalfield has oxidised and caused acidification of mine waste rocks (to pH 1) and mine waters (to pH 3). Similar or even greater amounts of pyrite occur locally at the nearby Kai Point mine, although the mined seam typically has <2 wt%S. However, dissolution of carbonate concretions in marine sediments immediately overlying the mined seam at Kai Point mine ensures that acid generated by pyrite oxidation is neutralised, and the site generally has substrates and waters with near‐neutral or alkaline pH. The close stratigraphic association between coal and marine sediments at Kai Point mine has resulted in high B contents in coal (up to 500 mg/kg) about 10 times higher than at the nearby Wangaloa mine. Both mines have elevated dissolved B contents in mine waters (up to 6 mg/L at Wangaloa). The Late Cretaceous coal‐bearing sequence at Ohai is entirely nonmarine, pyrite is rare or absent, and no environmental acidification occurs. Likewise, the Miocene coal‐bearing strata at Newvale coal mine have negligible pyrite and no acidification occurs from these rocks. However, iron sulfide cements have formed in Pliocene gravels from groundwater derived from rain with marine aerosols. Oxidation of this sulfide material has caused localised acidification at Newvale mine. Acidification has caused localised and generally short‐term elevation of dissolved trace elements at Wangaloa and Newvale mines, with dissolved Al up to c. 2.5 mg/L at Newvale. Suspensions of clay minerals cause turbidity at all mines. Well‐washed, coarse (>1 μm), detrital kaolinite at Kai Point, Wangaloa, and Newvale mines settles readily (within days). Chlorite from disaggregated labile clasts in overlying Pliocene gravels dominates longer term turbidity at Newvale, but the turbidity decreases rapidly on a time‐scale of months. Fine‐grained (including sub‐micrometre) poorly sorted authigenic kaolinite from labile clasts in the coal‐bearing strata at Ohai causes long‐term turbidity, with negligible setting over 9 months. The stratigraphically controlled processes quantified in this study can be used to predict the nature and scale of potential water quality changes in new coal mines in southern New Zealand.

Removal of surfactant from industrial wastewaters by coagulation flocculation process

Surfactants are among the most widely disseminated xenobiotics that contribute significantly to the pollution profile of sewage and wastewaters of all kinds. Among the currently employed chemical unit processes in the treatment of wastewaters, coagulation-flocculation has received considerable attention for yielding high pollutant removal efficiency. Jar-test experiments are employed in order to determine the optimum conditions for the removal of surfactants, COD and turbidity in terms of effective dosage, and pH control. Treatment with FeCl3 proved to be effective in a pH range between 7 and 9. The process is very effective in the reduction of surfactants and COD, the removals are 99 and 88 % respectively, and increased BOD5/COD index from 0.17 to 0.41. In addition to precipitation coagulation process, adsorptive micellar flocculation mechanism seems contribute to the removal of surfactants and organic matters from this rejection.

Theory of Transparency of the Eye

The present work relates the turbidity of the eye to microscopic spatial fluctuations in its index of refraction. Such fluctuations are indicated in electron microscope photographs. By examining the superposition of phases of waves scattered from each point in the medium, we provide a mathematical demonstration of the Bragg reflection principle which we have recently used in the interpretation of experimental investigations: namely, that the scattering of light is produced only by those fluctuations whose fourier components have a wavelength equal to or larger than one half the wavelength of light in the medium. This consideration is applied first to the scattering of light from collagen fibers in the normal cornea. We demonstrate physically and quantitatively that a limited correlation in the position of near neighbor collagen fibers leads to corneal transparency. Next, the theory is extended to predict the turbidity of swollen, pathologic corneas, wherein the normal distribution of collagen fibers is disturbed by the presence of numerous lakes-regions where collagen is absent. A quantitative expression for the turbidity of the swollen cornea is given in terms of the size and density of such lakes. Finally, the theory is applied to the case of the cataractous lens. We assume that the cataracts are produced by aggregation of the normal lens proteins into an albuminoid fraction and provide a formula for the lens turbidity in terms of the molecular weight and index of refraction of the individual albuminoid macromolecules. We provide a crude estimate of the mean albuminoid molecular weight required for lens opacity.