Chemical and Pharmaceutical Industry

The chemical and pharmaceutical industry is a high-technology production sector in which organic and inorganic raw materials are processed through controlled chemical reactions to produce active pharmaceutical ingredients and auxiliary chemicals. Production generally proceeds through raw material preparation, reaction, purification and formulation, with parameters such as temperature, pH and moisture controlled closely at each step.

Pharmaceutical production wastewater contains acidic or alkaline pH, a high COD load, solvent residues and sometimes heavy metals, so it cannot usually be discharged as it is. It must be treated with multi-stage processes such as pH neutralization, precipitation and biological treatment, so that the discharge limits defined in environmental legislation are met.

In the chemical industry, hydrated lime, Ca(OH)₂, is used in stages such as the neutralization of acidic wastewater, heavy metal precipitation, flocculation and flue gas treatment. Its pharmaceutical-grade form is used in antacid preparations. Dosage is usually controlled automatically according to pH, because overdosing increases sludge volume while underdosing can exceed discharge limits.

Quicklime (CaO) is used in chemical and pharmaceutical production in processes requiring high alkalinity, in the on-site production of milk of lime, and as a starting material in the synthesis of compounds such as calcium stearate and calcium chloride. Because it reacts strongly with water, it must be handled and slaked with appropriate care.

Milk of lime or ground dry lime is injected into the reactor, where it reacts with SO₂ and converts into calcium sulfite or sulfate. These calcium salts are captured as a solid in the filters, so the gas leaves with much less sulfur dioxide. Lime reactivity and grain size strongly influence how efficiently the SO₂ is captured.

For heavy metal precipitation in wastewater, the pH is generally kept in the 9-11 range, which is usually reached by dosing hydrated lime. In this window, zinc, nickel, copper and chromium precipitate in hydroxide form and are removed from the water as sludge. The exact optimum pH can vary with the metals present.

Pharmaceutical raw materials are transported with a moisture remover because many of them are hygroscopic, and contact with moisture causes active-ingredient degradation, caking or microbial risk. Lime-based desiccants keep ambient moisture within safe limits by binding the excess water in the container or storage space, which helps protect the material's quality during storage and transport.

Calcium hydroxide is used as an active ingredient in antacid formulations, as a buffer in dermatological preparations, and as an antimicrobial agent in root canal treatment in dentistry. In food, it is an acidity regulator under code E526. These uses require pharmaceutical-grade or food-grade material that meets the relevant specifications.

In chemical plant site infrastructure, limestone-based aggregate is used in concrete floors, fire lanes, warehouse foundations, road sub-bases and drainage lines. It is preferred for proper drainage in GMP-compliant facilities. The grain size and grading of the aggregate should be matched to each layer's function and the loads it must carry.

Lime-based solutions relate to environmental legislation as practical means of compliance. Hydrated lime, quicklime and gas-removing products are among the BAT components for achieving compliance with the discharge and emission limits under the Water Pollution Control and Air Pollution Control Regulations. The specific limits that apply to a facility should be checked in the current regulations.