Wastewater Characteristics and Treatment Considerations
Key Components in Wastewater
Sulfur
The sulfate ion is found naturally in most water supplies and in wastewater. Sulfur is required for the synthesis of protein and will be released later in the process of protein degradation. Sulfates are chemically reduced to sulfides and hydrogen sulfide (H2S) under anaerobic bacterial action. H2S released into the atmosphere in sewage systems that do not circulate under pressure tends to accumulate in the key of the pipes. The H2S can suffer cumulative biological
Read MoreLiquor and Whiskey Production: From Fermentation to Bottling
The liquor industry, considered from a global point of view, appears very fragmented. This is evident from the large number of manufacturers and the variety of packaging methods, production processes, and finished products.
What is Liquor?
Flavored-alcohol beverages are obtained by maceration, infusion, or distillation of various natural plant substances, flavored with distilled spirits, or by the addition of extracts, essences, and aromas allowed, or a combination of both, colored or not, with a
Read MoreUnderstanding Metal Corrosion: Types, Causes, and Control
Corrosion is the destructive attack of a material by chemical or electrochemical reaction with its environment. When etching is accompanied by physical damage, then there is corrosion-erosion, or corrosive wear by friction.
- It is a natural process; there is a transformation of the material to a more stable compound, which is an oxide.
- Plastic or wood do not corrode; they can crack or break down.
- Corrosion of iron leads to oxidation.
Two Kinds of Corrosion
- Dry: When an attack occurs via a chemical reaction,
Acid-Base Reactions and pH Calculations: Solved Problems
1. Identifying Conjugate Acid-Base Pairs
Identify the conjugate acid-base pairs in the following reaction:
CH3COO– + HCN ⇄ CH3COOH + CN–
Solution:
According to the Bronsted-Lowry theory, an acid is a chemical species that can donate an H+ ion. A base is a species that can accept an H+ ion. Therefore, by reacting an acid with a base, a new acid and a new base will always be formed.
Looking at the acid-base reaction of this problem:
CH3COO– + HCN ⇄ CH3COOH + CN–
You can see that the species CH3COO– (
Read MoreMetallic Bonds: Properties, Theories, and Characteristics
Properties of Metals
Metals, identified by their group number in the periodic table, share a set of similar properties:
- Electrical and thermal conductivity
- Metallic luster
- Malleability
- Ductility
Metals are electropositive, forming cations. They have few electrons in their valence shell. Their valence load results in positive oxidation numbers, and they are easily oxidized. All metals are solid at ambient temperature and pressure, except for mercury, which is liquid. These properties are due to their structure
Read MoreAtomic Models and Periodic Table of Elements
Atomic Models Through History
Dalton’s Atomic Model (1808)
Dalton proposed that matter is formed of small particles called atoms, which are indivisible and indestructible. He stated that all atoms of the same element are identical and that atoms of different elements are distinguished by their mass and properties. Therefore, all atoms of the same element have the same properties.
Thomson’s Plum Pudding Model (1904)
Thomson suggested that the atom was a positively charged solid sphere in which electrons
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