Challenges to Implementing Environmental-DNA Monitoring in Namibia

By identifying fragments of DNA in the environment, eDNA approaches present a promising tool for monitoring biodiversity in a cost-effective way. This is particularly pertinent for countries where traditional morphological monitoring has been sparse. The first step to realising the potential of eDNA is to develop methodologies that are adapted to local conditions. Here, we test field and laboratory eDNA protocols (aqueous and sediment samples) in a range of semi-arid ecosystems in Namibia. We successfully gathered eDNA data on a broad suite of organisms at multiple trophic levels (including algae, invertebrates and bacteria) but identified two key challenges to the implementation of eDNA methods in the region: 1) high turbidity requires a tailored sampling technique and 2) identification of taxa by eDNA methods is currently constrained by a lack of reference data. We hope this work will guide the deployment of eDNA biomonitoring in the arid ecosystems of Namibia and neighbouring countries.

The Analysis of Decision-making Items for Operation Management of Digital Twin Simulators for Sewage and Water Treatment Facilities

This paper addresses the derivation of decision-making factors for the operation and management of the Cyber Physical systems (CPS)-linked wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs) simulator. The analytical hierarchy process (AHP) method was applied to evaluate the importance of each influencing factor on the operational elements targeting experts. Here, the experts were 37 people working for WWTPs and 30 people working for DWTPs, respectively. The analysis factors for decision-making were influent load, reactor capacity, treatment process, occurrence of high turbidity influent, risk, urgency, response, and recovery, and their relative importance was analyzed. Among the operational elements of WWTPs, influent fluctuations have been shown as the most important factor. Conversely, the possibility of occurrence was found to be the most important influencing factor. In the case of DWTPs, the inflow of high turbidity was found to be the main operating factor, and the influencing factors were the probability of occurrence and the degree of risk. Based upon the results obtained, this study is expected to contribute to the establishment of a stable system of both WWTPs and DWTPS by identifying influent fluctuations, which are a major influencing factor, and by controlling operation factors connected with the establishment of a digital twin simulation.

Low turbidity in recirculating aquaculture systems (RAS) reduces feeding behaviour and increases stress-related physiological parameters in pikeperch (Sander lucioperca) during grow-out

There is a tendency to farm fish in low turbidity water when production takes place in the land-based recirculating aquaculture systems (RAS). However, the effect of water turbidity on stress and performance is unknown for many species cultured in RAS. The effect of different turbidity treatments as Formazine Attenuation Units (0 FAU, 15 FAU, and 38 FAU) on feed intake performance (latency, total feeding time, and total feed intake) and physiological blood stress parameters (cortisol, lactate, and glucose) in medium-sized pikeperch ((Sander lucioperca) n = 27, undetermined sex and age) of initial body weights of 508.13g ± 83 g (at FAU 0, 15 and 38, respectively) was investigated. The rearing system consisted of 9 rectangular tanks (200 L per tank). Fish were housed individually (n = 1, per tank, n replicates per treatment = 9). All tanks were connected to a recirculation system equipped with a moving bed biofilter. Feed intake in pikeperch kept at low turbidity (0 FAU) was 25% lower than pikeperch kept at high turbidity (38 FAU) (P<0.01) and also significantly (10.5%) lower compared to feed intake in pikeperch kept at intermediate turbidity (15 FAU) (P<0.01 for 0 FAU vs 15 FAU, feed intake sign. Value as the main effect is P<0.01). Pikeperch kept at low turbidity showed significantly slower feeding response (latency time) towards pellets entering the tank, shorter feeding times (both P< 0.05), and higher glucose blood concentration (73%) in contrast to pikeperch kept at highest turbidity. A reduction of 25% feed intake has obvious economic consequences for any fish farm and present data strongly emphasize the importance of considering the species-specific biology in future RAS farming.

Communication based on scattered laser radiation in a medium with high turbidity or in the presence of a noise source

The results of laboratory studies of an optical communication channel based on scattered radiation in the Big Aerosol Chamber of IAO SB RAS in a clean atmospheric environment, in the case of the chamber filled with vapor of the water-glycerin mixture, and in the presence of an noise laser source are analyzed. It is found that with the non-coplanar communication geometry in the chamber filled with the water-glycerin mixture, stable data transmission is possible with the azimuthal angle of orientation of the detector optical axis up to 5°. The error probability in the communication channel increases more slowly with an increase of the detector elevation angle in the chamber filled with the water-glycerin mixture than that in the chamber without this mixture does. The presence of an interfering laser radiation at a wavelength λ = 510 nm in the communication channel affects the communication quality. When the power of the noise laser source achieves 70 mW, the maximal error probability corresponds to 0.02.

Spectral Reflectance in the Spatial-temporal Dynamic of Turbidity, Itaipu Reservoir, Brazil

Water quality and the useful life of reservoirs and dams are influenced by the entry of suspended solids, in addition to reducing theirtransparency and storage capacity. It is primary to monitor and analyses its space-time dynamics. Thus, the objective of this work isto characterize the dynamics of the Itaipu Reservoir waters from turbidity, rainfall and spectral reflectance data. To characterize thedynamics, the reservoir was divided into 18 aquatic compartments between upstream and downstream, using precipitation data fromthe TRMM sensor and Landsat 8 images in different precipitation situations. NDWI, MNDWI and NDTI water spectral indexes werecalculated from Landsat 8 images. The results showed high correlation between the NDTI index and the turbidity (R² = 0.91). Then theNDTI images were reclassified into low, medium and high turbidity. A strong correlation between turbidity and 4 Band correspondingto the spectral range of red (R² = 0.94) was also obtained. The precipitation has a determinant influence, being the Paraná River, in theperiods of greater precipitation, the main agent in sediment transport. The space-time dynamics showed that the lateral compartmentsof the reservoir have less influence on sediment transport. In this sense, our analysis brought new elements to understand the turbidityvariation in these Itaipu Reservoir compartments, as well as the spectral reflectance dynamics in the space-time characterization relatedto turbidity.

Effects of different polymerisation conditions using hybrid polymer on high turbidity suspensions

Purpose In this study, new hybrid polymers composed of Zinc chloride (ZnCl2), acrylamide and chitosan were prepared at different ratios and temperatures. The effects of pH and polymer dosage were examined for different polymers to observe their efficiency in the removal of turbid water. The polymers’ zeta potential, morphology, elemental composition and functional groups were also identified and studied. Design/methodology/approach The free-radical polymerisation process was executed in the presence of N, N’-Methylene bis-acrylamide and potassium persulphate in one molar acrylamide solution. ZnCl2 and chitosan (CO) were later introduced into the suspension under nitrogen gas flow. Ratio and temperature were varied during polymerisation. The hybrid polymer produced, termed Polyacrylamide + chitosan oligosaccharide + zinc chloride (PAMCOZ), was analysed using Fourier transform infra-red spectroscopy attenuated total reflectance and scanning electron microscope with energy dispersive X-ray. The hybrid PAMCOZ was experimented with in high turbid kaolin suspension using jar testing analysis to see its ability as a coagulant. Findings The coagulation process using PAMCOZ with a ratio of 11 (3:2) at 70°C surrounding temperature showed a 100% reduction at pH 4 with 50 mg/L of the polymer. The functional groups present in ratio 11 polymer were hydroxyl, carbonyl, amide and methyl groups. In addition, several elements were spotted on the surface of PAMCOZ, such as zinc (Zn), carbon (C), chlorine (Cl), nitrogen (N) and oxygen (O). The effect of pH also demonstrated that PAMCOZ was unfavourable in an alkaline turbid water environment. Research limitations/implications Due to the research methodology approach, the research results may lack actual wastewater application. Therefore, researchers are encouraged to test the hybrid coagulant on raw wastewater, such as pulp and paper mill effluent with a high turbidity value similar to this study. Originality/value The polymerisation between zinc chloride, acrylamide and chitosan has not yet been applied. The different ratios and effects of temperature were analysed on PAMCOZ to see the turbidity removal. PAMCOZ showed better turbidity removal in acidic conditions.

Potential Applications of a Novel Ballast Water Pretreatment Device: Grinding Device

To investigate the removal efficiency of the grinding device (GD) as a potential replacement for the pretreatment filtration device of ballast water, solid grinding and viability experiment were conducted according to a treatment flow rate of 5 tons (Pilot test, PT), and 200 tons (Full-scale test, FST) per h. The solid grinding effect was observed in the particle size of ≥25 μm. Under the high-turbidity conditions (>300 mg L−1), no change in pressure (0.98 kgf/cm2) or stoppage in the GD were observed. The removal efficiency of the GD for >100 μm organism was determined to be 100% in both PT and FST, whereas the removal efficiency was determined to be 93% and 87% in the PT and FST, respectively, for the <100 μm organism. There was no statistically significant change in the removal efficiency stored within 2 h after passing through the GD, while the removal efficiency was determined to be ≥99% in the sample stored for 120 h. Future study is necessary to determine the additional removal efficiency according to the storage period after passing through the GD, but the GD might be utilized as the pretreatment device for the ballast water management system.

Technical evaluation of ultrafiltration unit in Siwalanpaji’s water treatment plant, PDAM Sidoarjo

Raw water with high turbidity requires pretreatment on its ultrafiltration unit to prevent fouling. Based on that, it is necessary to evaluate the ultrafiltration unit’s quality, quantity, and operation in Siwalanpanji’s WTP. The evaluation method compares the design criteria, technical specification, and ultrafiltration with the conventional to see the existing condition. The results of ultrafiltration turbidity and organic substance efficiency removal are about 53% and 18%, it’s not more good than conventional unit efficiency removal, which has 89% for turbidities removal and 37% for organic substance removal. Moreover, the quality of the production water fulfils the standards of Indonesia Health Minister No. 492 of 2010, except for the value of organic substances, which is in this analysis it around 13.69 mg/L meanwhile, in standard, it must not be more than 10 mg/L. Evaluation of the operating performance of each treatment unit related to the membrane unit at the WTP in Siwalanpanji has fulfilled the criteria design. However, using an ultrafiltration unit results in treated water quality is equivalent to a conventional treatment unit. So from this evaluation, it is found that there is a need for recommendations pretreatment, which is better for raw water to treat before ultrafiltration.