Greenhouse Irrigation Water Research Articles

Water reuse and resource recovery from greenhouse wastewater by capacitive electrodialysis at pilot scale

As food production dominates global freshwater consumption and nutrient discharge regulation tightens, the performance of novel technologies at applied scale needs to be studied to optimize water use and minimize environmental impact. Water reuse and the nutrient recovery from greenhouse wastewater were assessed utilizing one-pass capacitive electrodialysis (CED) at a pilot scale (19.32 m2 membrane area, 1–4 m3/day capacity), employing carbon-based electrodes. CED was optimized for key parameters, including applied voltage, cross-flow velocity, staging, water recovery, and varying feed concentrations. High-quality greenhouse irrigation water (conductivity<0.2 mS/cm and Na+ < 0.1 mmol/L) was produced, meeting specified guidelines. Na+ was retained less compared to Ca2+ and Mg2+ (86 % ± 4 %, 97 % ± 2 %, and 98 % ± 3 % removal, respectively) and nutrients concentration factors for K+, NO3− and PO43− reached up to 2.3 (596 ± 5 mg/L), 2.7 (1330 ± 20 mg/L), and 1.9 (130 ± 2 mg/L), respectively. There was no significant improvement in ion removal for all feed compositions beyond 12 V and 80 % water recovery. CED's specific energy consumption (SEC) with optimized parameters was 4-fold lower than the modeled RO system, and lower than previous electrodialysis studies. The highest SEC obtained was 0.24 kWh/m3. These findings suggest that CED is a promising technology for the greenhouse horticulture sector, aiding the move toward zero liquid discharge.

Early assessment of fungal and oomycete pathogens in greenhouse irrigation water using Oxford nanopore amplicon sequencing.

Water-borne plant pathogenic fungi and oomycetes are a major threat in greenhouse production systems. Early detection and quantification of these pathogens would enable us to ascertain both economic and biological thresholds required for a timely treatment, thus improving effective disease management. Here, we used Oxford nanopore MinION amplicon sequencing to analyze microbial communities in irrigation water collected from greenhouses used for growing tomato, cucumber and Aeschynanthus sp. Fungal and oomycete communities were characterized using primers that amplify the full internal transcribed spacer (ITS) region. To assess the sensitivity of the MinION sequencing, we spiked serially diluted mock DNA into the DNA isolated from greenhouse water samples prior to library preparation. Relative abundances of fungal and oomycete reads were distinct in the greenhouse irrigation water samples and in water samples from setups with tomato that was inoculated with Fusarium oxysporum. Sequence reads derived from fungal and oomycete mock communities were proportionate in the respective serial dilution samples, thus confirming the suitability of MinION amplicon sequencing for environmental monitoring. By using spike-ins as standards to test the reliability of quantification using the MinION, we found that the detection of spike-ins was highly affected by the background quantities of fungal or oomycete DNA in the sample. We observed that spike-ins having shorter length (538bp) produced reads across most of our dilutions compared to the longer spikes (>790bp). Moreover, the sequence reads were uneven with respect to dilution series and were least retrievable in the background samples having the highest DNA concentration, suggesting a narrow dynamic range of performance. We suggest continuous benchmarking of the MinION sequencing to improve quantitative metabarcoding efforts for rapid plant disease diagnostic and monitoring in the future.

Reliability and efficiency of an advanced tertiary treatment process for wastewater reclamation

Abstract A reliability study for the reclamation of wastewater treatment plant effluent using continuous sand filtration-multimedia filtration (CSF-MMF) combined with ultrafiltration (UF) and reverse osmosis (RO) has been conducted. The objectives of the research are two-fold: (1) effluent of CSF-MMF can be used for surface water supplementation and (2) permeate of UF-RO can be applied as greenhouse irrigation water. The removal efficiencies for nutrients and electric conductivity (EC) as well as some operational parameters of the pilot plant were investigated. The concentration of T-N, chemical oxygen demand (COD) and turbidity in the filtrate of CSF-MMF with external C-course methanol dosage and FeCl3 dosage could be kept at less than 2.2 mg/L, 35 mg/L and 0.9 NTU respectively. Average EC exceeded the required surface water standard by 10% and it was difficult to meet the low surface water standard for T-P (below 0.15 mg/L). The EC of RO permeate was below 20 μS/cm, which was much lower than the standard for greenhouse irrigation. With frequent back flushes, cleaning in place (CIP) and enhanced cleaning the UF could be operated with a constant permeability of 100 L/(m2·h·bar). An appropriate CIP resulted in a recovery of 47–52% of the RO. The protective cartridge filter prior to the RO should be replaced every 2 weeks.

Controlling Pathogens and Chemical Contaminants in Greenhouse Irrigation Water through Electrochemical Processes

The capture and re-use of greenhouse irrigation/fertigation water is an efficient use of ever more limited water resources. Although, when capturing and re-applying fertigation solutions there is a greater risk for both pathogen proliferation and chemical contaminant accumulation, both of which can lead to reduced productivity and, in more severe cases, crop loss. In order to avoid these obstacles, it is important that grower’s employ some form of water treatment. Electrochemical disinfection can be used to treat irrigation water by producing and recycling chemical components, in situ, that limit pathogen proliferation while degrading chemical contaminants. Two electrode types (Dimensionally Stable Anodes &amp; Boron-Doped Diamond) using regenerative in situ processes are tested and will be evaluated on their suitability for crop production. Upon analyzing the electrochemical systems’ ability for disinfection and organic pollutant degradation, they appear to be compatible with crop production following preliminary trials.

Modelling the selective removal of sodium ions from greenhouse irrigation water using membrane technology

Modelling the selective removal of sodium ions from greenhouse irrigation water using membrane technology

Modelling the selective removal of sodium ions from greenhouse irrigation water using membrane technology

A model is presented for the Na+ and K+ levels in the irrigation water of greenhouses, specifically those for the cultivation of tomato. The model, essentially based on mass balances, not only describes the accumulation of Na+ but includes a membrane unit for the selective removal of Na+ as well. As determined by the membrane properties, some of the K+ is removed as well. Based on real-life process parameters, the model calculates the Na+ and K+ concentration at three reference points. These process parameters include the evapotranspiration rate, the K+ uptake by the plants, the Na+ and K+ content of the fertilizer, the Na+ leaching out from the hydroponic substrate material, and the Na+ and K+ removal efficiency of the membrane unit. Using these parameters and given a constant K+ concentration of the irrigation water entering the greenhouse of 6.6mM (resulting in the optimal K+ concentration for tomato cultivation), the composition of the solution is completely defined at all three reference points per irrigation cycle. Prime aim of this investigation is to explore the requirements for the selective membrane that currently is developed in our lab. It is found that even for a limited Na+ over K+ selectivity of 6, after a number of cycles the Na+ level reaches steady state at a level below the upper (toxic) threshold for tomato cultivation (20mM). Economic aspects and ways of implementation of such a system are briefly discussed.

CFD Simulation of Heating Process of Greenhouse Irrigation Water in Wintering Period

Abstract. In order to solve the problem of low greenhouse irrigation water temperature during the wintering period, the heating process of irrigation water in heating reservoir was investigated under the combined effect of air heat and soil heat with solar greenhouse in Xinyi Town, Lishi District, Shanxi Province as the carrier using three-dimensional non-steady-state methods in computational fluid dynamics (CFD). A dynamic computational model was established to predict the heating process of irrigation water. The measured data were used to reveal the dynamic hexahedron boundary conditions of the heating reservoir in the greenhouse. The simulation results of computation model were validated, and the errors and causes were analyzed. It was shown that the simulated heating process of irrigation water was consistent with the measured data under the influence of changes in boundary conditions, with an average relative error &amp;lt;5.46% and the maximum absolute error of &amp;lt;1.64°C; the correlation coefficient between the simulation values and measured values was greater than 0.96, indicating that CFD simulation of heating process of irrigation water is feasible. Keywords: Agricultural engineering, CFD simulation, Greenhouse, Irrigation water temperature, Solar greenhouse heating reservoir, Three-dimensional non-steady-state, Wintering period.

USE OF THE DELPHI EXPERT ELICITATION TECHNIQUE TO RANK FOOD SAFETY RISKS IN GREENHOUSE TOMATO PRODUCTION

One half of fresh tomato sales in the US are from greenhouse grown crops. Fresh tomato was linked to a number of foodborne disease outbreaks. Collectively, foodborne and phytopathogen hazards threaten both public health and economic viability of the greenhouse industry. Management practices in tomato greenhouses in North America were documented previously. In this study, a systematic, internet-based, iterative Delphi method was used to gauge opinions about the potential impact of various greenhouse management factors (water management, workers, environment and greenhouse design, equipment sanitation, animals, waste, and traceability) on food safety. The pretested questionnaire was distributed to 20 national and international experts in food safety of fresh fruits and vegetables. The Delphi process was repeated until the criteria for consensus were satisfied (expert agreement ≥70%). Expects attributed greenhouse irrigation water as a highly important source of contamination with human pathogens. Accordingly, testing of irrigation water for human pathogens was considered to be a valuable tool in controlling contamination in the greenhouse. According to this expert panel, people may occasionally introduce pathogens into the greenhouse. Hand washing and footwear were ranked the most effective in preventing contamination from employees and visitors. The majority of experts believed the presence of human pathogens in the greenhouse environment presented an important source of contamination for edible tomato fruits. Experts also agreed that livestock and poultry operations should be at least 250 feet away from the greenhouse. Although any animal intrusion was considered a high-extreme food safety risk-rodents were ranked the highest, and cats the lowest. Employee hygiene, mode of irrigation, equipment sanitation was ranked the most important management practice in prevention of contamination with human pathogens.

Interactions of Heterotrophic Bacteria from Recycled Greenhouse Irrigation Water with Plant Pathogenic Pythium

Heterotrophic bacteria present in recycled greenhouse irrigation water (RIW) were characterized and then evaluated for their effect on Pythium aphanidermatum, P. cryptoirregulare, and P. irregulare. Nutrient agar (NA) and R2A agar were used to isolate copiotrophic and oligotrophic bacteria. Bacterial isolates recovered from RIW were categorized according to whether they inhibited Pythium growth, attached to hyphae, or enhanced Pythium growth in the three Pythium species used. Three bacterial isolates were selected to determine whether their in vitro interactions with Pythium aphanidermatum, the most pathogenic of the three species used, influenced disease development in the greenhouse. An isolate of Sphingobium sp. that inhibited Pythium, Pseudomonas sp. that attached to hyphae, and Cupriavidus sp. that enhanced the growth of P. aphanidermatum in vitro were used in greenhouse experiments to examine their effects on disease development in geranium (Pelargonium ×hortorum ‘White Orbit’) grown in pasteurized potting mix in ebb and flood irrigation systems. Disease progress curves evaluating the effect of each bacterium indicate that they did not suppress or enhance disease development (P = 0.05). Thus, the effects that the bacterial isolates had in vitro differed from their effects under greenhouse conditions.

MONITORING OF GREENHOUSE IRRIGATION WATER USING MICROCHIP ELECTROPHORESIS

Management of water and nutrients must be improved to reduce water quality problems and emission of nutrients to the environment. With microchip capillary electrophoresis (CE) technology, more precise monitoring of the process of irrigation and recirculation is possible in relation to plant needs. A mobile microchip CE platform was developed for performing on-site analysis of greenhouse irrigation water and nutrient solution. Microchip CE offers unique possibilities for fast and automated determination of ions in water. Each measurement produces concentration values of the NH4+, NO3-, K+, Ca2+, SO42-, Na+, Mg2+, Cl-, HCO3- and H2PO4- ions. With the use of CE technology several measuring sessions were organized in commercial growing farms to study water and nutrient management of crops grown on hydroponics. Samples of drip, slab and drain water at four growing sites, with cucumber and rose crops in autumn climate conditions, were collected on daily and hourly basis during daylight. Variation of the analysis results (expressed as percentage from 24 hour average) during the day can be substantial, with up to 57% for potassium in the root medium. Variation in the slabs was larger than in dripwater, which in turn exceeds drainwater. Variation of individual nutrients was greater than of EC and pH. Variation within a single day was as large as between several days.

Response of hydroponic tomato to daily applications of aqueous ozone via drip irrigation

Recycling of greenhouse irrigation water in hydroponic tomato production requires a water remediation process to reduce the risk of pathogen proliferation and the accumulation of other chemical compounds. The dissolution of ozone into bulk irrigation solutions is an effective technology for reducing chemical contaminant and pathogen levels in greenhouse irrigation water. Greenhouse managers utilizing ozonation typically remove residual ozone prior to distribution to the crop. Removal of the active compound in this treatment process has been deemed a prudent measure intended to prevent ozone-based plant damage. This said, although atmospheric ozone has been extensively studied with respect to its phytotoxicity, there are very few studies available on ozone in the aqueous phase in which evidence to support the removal of ozone (on the basis of phytotoxicity) is provided. Furthermore, removal limits the overall efficacy of the treatment as the ozone is not available to treat distribution lines and emitters. The purpose of this study was to determine if aqueous ozone impacts tomato ( Lycopersicon esculentum Mill. cv Matrix F1) productivity when applied directly to a mineral wool growth substrate via drip irrigation. At the highest aqueous ozone treatment level (3.0 mg L −1) significant increases in leaf area, shoot dry matter, and stem thickness were observed. There were no differences across all treatments in terms of net CO 2 assimilation rate, stomatal conductance, internal leaf CO 2 concentration, chlorophyll content index, and fruit production. A qualitative assessment of algae growth on the substrate surface was conducted. Both ozone treatments resulted in a visually discernible reduction in algae prevalence on the substrate surface. The results of this study do not support the removal of aqueous ozone (at the concentrations examined) prior to distribution when the solution is applied via drip irrigation in mineral wool hydroponic tomato production.

Development of a real‐time PCR assay for Pseudomonas cichorii, the causal agent of midrib rot in greenhouse‐grown lettuce, and its detection in irrigating water

Midrib rot is an emerging disease in greenhouse production of lettuce caused by Pseudomonas cichorii, and probably introduced through contaminated irrigation water. Concentrations of 100 CFU mL−1 are enough to induce the typical midrib rot symptoms. A sensitive real‐time PCR assay was developed, based on a 90‐bp amplicon from the pathogenicity gene cluster hrcRST and a Taqman Minor Groove Binding probe. Specificity of the assay was tested with 39 P. cichorii strains, including the type strain, and 89 strains from 83 other Pseudomonas species. The relationship between detection signals and P. cichorii DNA concentrations was linear over 6‐logs. Detection threshold with excellent reproducibility was 500 fg of DNA or about 70 genome copies. Sample preparation and DNA isolation were optimized to allow detection in 1 L water samples. The assay was first evaluated with greenhouse irrigation water spiked with serial dilutions of P. cichorii. The calculated cell numbers obtained with real‐time PCR were 10‐fold lower than plate counts of actual spiked cells. However, the assay consistently detected 100 CFU per reaction, corresponding to the detection of 1 CFU mL−1 of irrigation water, which is well below the concentration needed for midrib rot infection. Finally, the assay proved to be valuable for detecting infective P. cichorii concentrations in the irrigation water of a commercial lettuce production greenhouse.

Effects of saline root environment (NaCl) on nitrate and potassium uptake kinetics for rose plants: a Michaelis–Menten modelling approach

Greenhouse-grown cut flower roses are often irrigated with moderately saline irrigation water. The salt/ballast ions are either present initially in poor quality raw water or reclaimed municipal water, or accumulated in greenhouse irrigation water that is captured and reused. Such ions can inhibit root absorption of essential nutrients. The objective of this work was to quantify the influence of NaCl concentration on the uptake of nitrate and potassium by roses and develop a predictive model of uptake inhibition based on NaCl, NO3 −, and K+ concentration. One year-old rose plants (Rosa spp. ‘Kardinal’ on ‘Natal Briar’ rootstock) were moved into growth chambers where nitrogen and potassium depletion were monitored during 6 days. Eight different initial NaCl treatments varying from zero to 65 mol m−3 were used and within these there were two initial NO3 − and K+ concentrations: high concentration (HC, 7.0 mol m−3 and 2.6 mol m−3 NO3 − and K+ respectively) or low concentration (LC, 3.5 mol m−3 and 1.3 mol m−3 NO3 − and K+ respectively). Plant NO3 − uptake was negatively affected by NaCl concentration. NO3 − maximum influx (Imax) declined from 5.1 µmol to 2.5 µmol per gram of plant dry weight per hour as NaCl concentration increased from zero to 65 mol m−3. A modified Michaelis–Menten (M–M) equation taking into account inhibition by NaCl provided the best fit for NO3 − uptake in response to varying NaCl concentration. K+ uptake was unaffected by NaCl concentration. A M–M equation that did not include inhibition was suitable for describing K+ uptake at varying NaCl concentration. The resulting empirical models could assist with decision making, such as: adjustment of NO3 − fertilization based on NaCl concentration, necessity of water desalinization, or determination of the desired leaching fraction.

Analysis of on-farm irrigation performance in Mediterranean greenhouses

A comprehensive irrigation assessment was conducted using on-farm water use information and simulated crop water requirements in a Mediterranean greenhouse area, mainly dedicated to horticultural crops, located on the Almería coast. The mean irrigation water supply (IWS) for the main greenhouse crop cycles was 228 mm and ranged from 158 mm (autumn green bean) to 362 mm (autumn–spring sweet pepper). Besides, the mean AIWS value for the main crop rotations was 444 mm and ranged between 363 mm for autumn–spring sweet pepper and 502 mm for autumn–winter pepper and spring melon. Mean relative irrigation supply (RIS) values were close to 1 for most greenhouse vegetable crops, indicating that, on average, the irrigation supply matched the maximum water requirements of these crops. By contrast, the mean RIS value of autumn–winter cucumber was 1.6, indicating that, on average, the irrigation supply clearly exceeded the calculated optima. However, for most crops, the high CV values observed for RIS and the analysis of the RIS dynamics throughout the cycles indicate that there are greenhouse crops and crop cycle periods for which the IWS clearly does not match the crop water requirements. Greenhouse irrigation water use in the Almería coastal region can, therefore, be improved. Mean irrigation water use efficiency (IWUE) values for greenhouse horticultural crops ranged from 15.3 kg m −3 (autumn–winter green bean) to 35.6 kg m −3 (spring watermelon). They were, in general, higher than those found when these crops were grown outdoors in similar climatic regions. Water productivity (WP) varied from 7.8 to 15.9 € m −3 and were highest for green bean crops. WP values of greenhouse crops were generally much higher than those found in other irrigation districts around the world, including Mediterranean areas, due to the low IWS and, especially, to the high value of the vegetable crops grown off-season.

(69) Use of Hypochlorous Acid for Treatment of Greenhouse Irrigation Water

Scaling from dissolved and suspended solids in irrigation water reduces the efficiency of greenhouse irrigation systems. Water deposits inside pipes reduce water flow and deposits may reduce the flow through irrigation emitters, often clogging them. If not properly maintained, the clogging of emitters requires constant maintenance. This results in considerable labor expense and/or emitter replacement. Scaling inside irrigation system pipes also has the potential to harbor plant pathogens from the resulting biofilms. Oxcide, a novel hypochlorous acid (HOCl) compound, is produced electrochemically by removing sodium and hydroxide from sodium hypochlorite. The elimination of sodium hydroxide from the product creates a nontoxic oxidizer. A system to inject Oxcide into irrigation water at a commercial Colorado greenhouse was installed to maintain irrigation efficiency of emitters and irrigation lines during Winter 2003. The oxidation reduction potential (ORP) was monitored and visual evaluations of irrigation equipment in the Oxcide treated zones compared to those zones not treated with Oxcide was conducted. During January through March, geranium stock plants were irrigated with water that maintained ORP levels at around 600 mV. Visual ratings of the irrigation emitters revealed that the injection of Oxcide in the irrigation water did reduce the level of deposition. Deposition on the main feed lines was so thick that they hindered the complete closure of existing valves. Treatment of the irrigation water Oxcide injection for six months successfully removed of the scale and deposits from the water line.

WATERGY: INFRASTRUCTURE FOR PROCESS CONTROL IN A CLOSED GREENHOUSE IN SEMI-ARID REGIONS

Abstract A novel solar humid-air-collector system for combined water treatment, space-cooling and ?heating has been designed in an EU framework-5 financed project called Watergy. The design consists of a construction of two prototypes for applications in architecture and greenhouse horticulture: a South European variant (for arid climate and emphasis on agricultural use) and a Central-/North European variant (for temperate climate and emphasis on integral building design). The core is the development of a collector system, following the principle of a closed, two phase thermo siphon. It achieves combined evaporation and ?condensation, efficient heat transfer to a central heat exchanger as well as increased heat conduction from (humid) air to water. Main improvements are cost reduction in space heating and -cooling of buildings and greenhouses. Furthermore, viability increases by additional integration of greenhouse irrigation water recycling, desalination and building grey-water recycling. Sensors and actuators, connected to low-level controllers, activate a model-based control system to manage these processes. The paper describes the different appendages, sensor systems, network connections, databases, alarming systems, user interfaces and remote management from the Netherlands to Spain through the Internet.

Greenhouse irrigation water depths in relation to rose stem and bud qualities

The cultivation of roses occupies a special place in the flower production of Brazil, the concern with the quality of the buds being intimately related with the appropriate supply of water and nutrients to the plant. With the objective of evaluating stem and bud quality the rose variety 'Osiana' was cultivated in a greenhouse using different irrigation water depths based on fractions of pan evaporation (0.25, 0.50, 0.75, 1.00 and 1.25). The experimental design consisted of total randomized blocks with five replications and five treatments. There is a linear tendency of increasing the length and diameter of the stems and the length and diameter of the buds with increasing irrigation water depths.

Geographical Characterization of Greenhouse Irrigation Water

Chemical analyses of 4306 randomly selected greenhouse water samples for 1995 from the United States and Canada were obtained from four analytical laboratories and graphically characterized using a distribution analysis. For pH, electro-conductivity (EC), and nutrient concentrations, a mean and median value and the percentage of samples with concentrations above or below those generally considered acceptable are presented for all samples and the 10 leading states in floricultural production. The median nutrient concentrations were more representative of the type of water found throughout the United States and Canada than that of the mean values because of the unequal distribution of the data. The overall median water source had a pH of 7.1; an EC of 0.4 dS·m−1; an alkalinity of CaCO3 at 130 mg·L−1; (in mg·L−1) 40 Ca, 11 Mg, 8 SO4−S, 13 Na, 14 Cl, 0.02 B, and &lt;0.01 F; a Ca: Mg ratio of 3.2, and a sodium adsorption ratio (SAR) of 0.7. The information presented characterizes irrigation water and may assist in developing more refined fertilizer recommendations for greenhouse crop production.

DEVELOPMENT AND ASSESSMENT OF AN ACIDIFICATION CALCULATOR FOR IRRIGATION WATER ALKALINITY REGULATION

Excessive alkalinity in greenhouse irrigation water can increase substrate solution pH, resulting in reduced micronutrient availability for plants. A spreadsheet was designed to offer a quick and practical method for calculating: 1) amount of nitric, phosphoric, and sulfuric acid required to achieve an endpoint alkalinity or pH in irrigation water; 2) the amount of nutrients added by the acid addition; and 3) acid costs. It calculates both pH and alkalinity of irrigation water after acidification, regardless of the endpoint selected. The spreadsheet accounts for the pH-dependent reaction that determines the relative percentage of each of the carbonate species—carbonates (CO 2–3), bicarbonates (HCO–3), and carbonic acid (H2CO3)—present in the solution. In addition, the acidification calculations account for the dissociation characteristics of the acid selected to neutralize the alkalinity. The spreadsheet was validated with six water sources from Indiana and North Carolina. Alkalinity neutralization was achieved within an acceptable range (greatest deviation from predicted pH was 0.16 units; greatest deviation from predicted residual alkalinity was 0.21 meq·liter–1) for both target endpoint pHs and endpoint alkalinity concentrations. The mathematical model used in the spreadsheet development provides a chemical basis for acidification and provides results useful for making grower recommendations for acid additions to irrigation water for alkalinity neutralization.

A novel approach to calculate acid additions for alkalinity control in greenhouse irrigation water

Abstract Excessive alkalinity in greenhouse irrigation water can increase substrate solution pH, resulting in reduced micronutrient availability for plants. A spreadsheet was designed to offer a quick and practical method for calculating: 1) amount of nitric, phosphoric, and sulfuric acid required to achieve an endpoint alkalinity or pH in irrigation water; 2) the amount of nutrients added by the acid addition; and 3) acid costs. It calculates both pH and alkalinity after acidification, regardless of endpoint selected. The spreadsheet accounts for the pH dependent reaction which determines the relative percentage of each of the carbonate species ‐carbonates (CO3 2‐), bicarbonates (HCO3 ‐), and carbonic acid (H2CO3) ‐ present in the solution. In addition, the acidification calculations account for the starting pH of the solution, the alkalinity found in the initial solution, and the dissociation characteristics of the acid selected to neutralize the alkalinity. The spreadsheet was validated with six water ...