Soil pH was measured with a glass electrode (HQ440D, HACH, USA) (water:soil = 2.5:1). Soil available phosphorus (AP), available potassium (AK), and available nitrogen (AN) were determined by molybdenum blue colorimetric method, flame photometry method, and the alkaline hydrolysable diffusion method, respectively. Soil organic matter (OM) was determined by potassium dichromate titration method (Bao, 2000 ). Soil acid phosphatase (ACP), alkaline phosphatase (ALP), sucrase (SUC), and urease (URE) were measured using a soil enzyme activity assay kit (Beijing Solarbio Co., Ltd. Beijing, China)
Hq440d
Manufactured by HACH
Sourced in United States, Germany
The HQ440d is a portable, multiparameter digital meter that can measure pH, conductivity, dissolved oxygen, and other water quality parameters. It provides accurate and reliable measurements with a simple user interface.
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8 protocols using hq440d
1
Soil Physicochemical and Enzymatic Properties
2
Soil Sample Characterization and Analysis
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The initial background soil sample before the experiment and irrigated pot soils after harvest were collected, air-dried, and powdered into <2 mm size using an electric grinder and stored in plastic bottles for laboratory analysis. The background soil particle size distribution was measured using the hydrometer method (Gee and Bauder, 1986 ). Next, both background and irrigated soils pH and EC were measured in a 1:5 (soil: water) suspension using pH meter (HACH® HQ440d, Loveland, USA) and conductivity meter (Orion, EA 940 USA) respectively (Pawar and Shah, 2009 ). Soil OC was determined using Walkely and Black method (Nelson and Sommers, 1996 ), and OM was also estimated from OC by multiplying with a 1.724 conversion factor. Whereas, TN was measured using the Kjeldahl method (Bremner and Mulvaney, 1982 ). Soil TP and exchangeable cations (Na+, K+, Ca2+, and Mg2+) were determined by the Mehlich-3 extraction method (Mehlich, 1978 ) using inductively coupled plasma (ICP - OES, Arcos spectrophotometer, Germany). The soil SAR was computed using Eq. (5) suggested by Richards (1954) .
3
Physicochemical Analysis of Composted Manure
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For the laboratory analyses of the physicochemical properties of the composted manure substrates, the base suspension that was used before in the bacteriological examination was used. For the determination of total nitrogen, the samples were first mineralized and then digested by the Digesdahl Digestion Apparatus model 4436-20 (HACH, Düsseldorf, Germany), with subsequent steam distillation with NaOH. The ammonium ions (NH4+) were analyzed by steam distillation and titration as well. The determination of total organic carbon in substrates to determine the C/N ratio is described in Renčo et al. [23 (link)]. The determination of phosphorus from the base suspension was conducted by spectrophotometer, Lange DR 2800 (HACH, Düsseldorf, Germany). The resulting absorbance was calculated based on the content of total phosphorus. pH was determined by direct measurement of the base suspension (1:10 in sterile water) with a glass electrode using a laboratory multi-meter, HQ440D (HACH, Düsseldorf, Germany). Dry matter was determined from the residual weights of dried samples at 105 °C. After burning the dried samples from the residue for four hours at 550 °C, the amount of ash was determined as well. The organic matter content was calculated as follows [24 (link)]:
4
Comprehensive Compost Characterization and Curing
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The temperatures in each pile were measured using Certeza FT 707 digital thermometers. The evaluation of all parameters was done in duplicate. Water extract (1 : 10) for pH estimation was collected by shaking homogenized samples in distilled water for 15 minutes. A pH meter (HQ440 d) multi-HACH fitted with a glass electrode was used for pH measurement. To determine total nitrogen, samples were wet-digested using a HACH-Digesdahl apparatus, and the digestate aliquot was steam distilled with 40% NaOH. The moisture content of collected samples was determined by the AOAC method [31 ]. The compost's total phosphorus, potassium, and carbon content were determined by AOAC atomic absorption spectrometer (2000). OM was determined by dry combustion at 550°C. The size distribution of particles in the compost was assessed by sieving the compost in a water-jet sieving system, in which the water pressure of the jet pushed a spraying arm with 34 nozzles to revolve over each sieve [32 (link)]. The curing composting stage is frequently followed by a curing period. The materials will continue to decompose slowly during the curing phase. Materials continue to degrade until the remaining microbes eat the last easily degraded source materials. The compost has become relatively stable and manageable [33 ]. The curing stage of compost usually lasts 3 to 4 weeks.
5
Salinity Measurement of River Water
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Conductivity and pH were measured with a multi-digital meter (HACH HQ440d, Germany). NH 4 + -N and COD were analyzed with HACH Lange GMBH kits and measured with the DR 3900 spectrophotometer (HACH LCK 304 and LCK1414, Germany) (Table S1, Table S2) (Saha et al. 2020) (link). The electrical conductivity of fresh Rhine River water samples was then calculated into salinity by a standard curve (Figure S1). These calculations demonstrated that the Rhine River water samples had an average salinity of 0.4 ± 0.1 ppt.
6
Physicochemical Characterization of Raw Clay Soil
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The raw clay soil was characterized for pH (ISO 10390: 2014), electrical conductivity (ISO 11265: 2014), organic matter (Walkely-Black), total nitrogen (Kjeldahl), cation exchange capacity (ammonium acetate), and calcium carbonate (acid neutralization). UV-Vis absorption studies were conducted using a spectrophotometer (DR 6000, HACH, USA) at 200–900 nm wavelength with a 1 nm scanning step. The crystalline structure was examined using X-ray diffraction (Bruker D8, Bremen, Germany) with a Cu Kα source (λ = 1.5406 Å) from 10° to 70° (2θ) at a scanning rate of 2° min−1. The functional groups were studied by FTIR spectroscopy (Spectrum 65, PerkinElmer, USA) in the range of 400–4000 cm−1 with a resolution of 4 cm−1 using KBr pellets. The samples were analyzed in the powder form (ATR) technique. The pH value was measured by a multi pH meter with a resolution capacity of pH 0.001–0.1 (HQ440D, HACH, USA). The adsorbent surface morphology was examined using Scanning Electron Microscopy (SEM) operating at 15 kV (JCM-6000Plus, JEOL Ltd., Japan). The SEM images were analyzed using ImageJ software (v1.53k).
7
Water Sample Collection and Analysis
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In each stream, a water sample (1 L) was collected in plastic bottles and stored at −20 °C. After thawing, subsamples were taken for the following measurements. Conductivity and pH were measured from a subsample of about 50 ml in a glass vial with a portable multi sensor meter (HQ440d HACH), and a 15 ml subsample was taken to measure turbidity (Hach 2100Q meter) in the laboratory at 20 °C. A filtered (0.2 µm GFC filter) 10 ml subsample was taken in polystyrene tubes for ammonium (NH4+), nitrate (NO3−), nitrite (NO2−) and phosphorus (PO43−) measurements, analysed with a Skalar SAN++ segmented flow analyser packed with a 1074 twin needle autosampler, and software Flow Access v3.
8
Characterization of Polyamide Membrane Performance
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A plate-and-frame bench-scale cross-flow membrane module was adopted to characterize the performance of the polyamide membrane (Figure 1A). 46 The custom-built module had flow channel dimensions of 8.0 cm in length, 3.0 cm in width and 1.0 mm in thickness, and was capable of accommodating up to 70 bar of feed pressure. Cross-flow was maintained using positive displacement pumps (Hydra-Cell F20). A pulsation dampener (Hydra-Cell 4CI SST) was installed upstream of the membrane module to negate pressure pulsations.
Pressure transducers with 1 % reading uncertainty (Wika A-10) were installed along the feed and permeate flow streams to monitor the flow pressure in real-time on the LabView software. The water flux was determined by gravimetry, using a digital mass scale with 0.1 g readability (Ohaus Scout Pro SP601). The solution conductivity and pH levels were monitored and recorded at 1 Hz frequency (Hach HQ440d). Streaming potential experiments were conducted with the Anton Paar SurPASS 3 zeta potential system.
Pressure transducers with 1 % reading uncertainty (Wika A-10) were installed along the feed and permeate flow streams to monitor the flow pressure in real-time on the LabView software. The water flux was determined by gravimetry, using a digital mass scale with 0.1 g readability (Ohaus Scout Pro SP601). The solution conductivity and pH levels were monitored and recorded at 1 Hz frequency (Hach HQ440d). Streaming potential experiments were conducted with the Anton Paar SurPASS 3 zeta potential system.
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