Journal of Dairy Research cambridge.org/dar Review Article Cite this article: Ekka B, Dejus S and Juhna T. Case study on the dairy processing industries and their wastewater generation in Latvia. Journal of Dairy Research https://doi.org/ 10.1017/S0022029921000819 Received: 8 February 2021 Revised: 16 August 2021 Accepted: 23 August 2021 Key words: Dairy wastewater; environmental pollution; Latvian dairy industry; BOD; COD; total solids Author for correspondence: Basanti Ekka, Email: basanti.ekka_1@rtu.lv © The Author(s), 2021. Published by Cambridge University Press on behalf of Hannah Dairy Research Foundation Case study on the dairy processing industries and their wastewater generation in Latvia Basanti Ekka, Sandis Dejus and Talis Juhna Water Research and Environmental Biotechnology Laboratory, Riga Technical University, Riga, Latvia Abstract The objective of the research presented in this Research Communication was to access the environmental impact of the Latvian dairy industries. Site visits and interviews at Latvian dairy processing companies were done in order to collect site-specific data. This includes the turnover of the dairy industries, production, quality of water in various industrial pro- cesses, the flow and capacity of the sewage including their characteristic, existing practices and measures for wastewater management. The results showed that dairy industries in Latvia generated in total approximately 2263 × 10 3 m 3 wastewater in the year 2019. The Latvian dairy effluents were characterized with high chemical oxygen demand (COD), bio- logical oxygen demand (BOD) and total solids (TS). Few dairy plants had pre-treatment facil- ities for removal of contaminants, and many lacked onsite treatment technologies. Most facilities discharged dairy wastewater to municipal wastewater treatment plants. The current study gives insight into the Latvian dairy industries, their effluent management and pollution at Gulf of Riga due to wastewater discharge. Billions of people around the world consume dairy products each day as part of their daily nutrition. The global demand for milk and its products is produced by approximately 270 mil- lion cows. Not only are milk and dairy products an active source of nutrition, but also present income opportunities for millions of farmers, processors, shopkeepers and other stakeholders around the world. Specifically, the European dairy sector holds higher position in terms of pio- neering markets in the food sector to consume around 45 million metric tons of fresh milk products annually (Burrell, 2000). Dairy production materializes in all EU member countries and represents a noteworthy proportion of the value of EU agricultural output. Total milk pro- duction in EU is estimated to be 155 million tons per year. Although Germany, France, Poland, the Netherlands, Italy and Spain are the leading producers of milk, the Baltic states account for a major share in the rest of the European region. The contribution of the dairy sector to the GDP of the Baltic states is considerable. With population of 1.91 million, Latvia is characterized by extensive rural and coastal areas where agriculture is an important economic activity. Milk production is one of the most important sectors, and it is the second-biggest sub-sector of agriculture in Latvia. Presently, the number of dairy cows is one-fourth of the number back in 1938 and one-third of it in 1990. In 2014 there were 21 800 dairy farms with the average herd size of 7.6 cows and 40 com- peting milk processors (Thomassen and Boer, 2005). Despite the decreasing cow number, milk production in Latvia continues to increase, due to larger farms that choose genetically improved breeds for high milk production. The current case-study brings in the total of 58 registered milk processing industries in Latvia. These dairy industries produce a different kind of dairy products for both local consumption and export to other countries. Although the industry provides protein rich food, it generates a huge amount of wastewater as the pro- cessing of milk and dairy products demands a large quantity of water. Subsequently, the indus- try may create a lot of water contamination with suspended and dissolved solids, soluble organic and inorganic matter, etc. in the wastewater effluents (Tamminga, 2003; Chandra et al., 2018). Protein, fat, and carbohydrate accounts for a significant organic load in dairy was- tewater. Additionally, dairy wastewater contains acid, alkali, detergents, disinfectants (e.g., chlorine, hydrogen peroxide, and quaternary compounds of ammonia) along with a significant microbiological load (potentially including pathogenic viruses and bacteria) (Bortoluzzi et al., 2017). The dairy industry, on an average, generates 2.5–10.0 l of wastewater per liter of milk processed (Bharati and Shinkar, 2013; Ashekuzzaman et al., 2019). Typically, dairy wastewater is characterized by a high biological oxygen demand (BOD: 40–8240 mg/l), chemical oxygen demand (COD: 430–18 045 mg/l), suspended solids (SS: 24–4500 mg/l) and nutrients such as total nitrogen (TN: 14–830 mg/l), and total phosphorus (TP: 9–280 mg/l) (Danalewich et al., 1998; Sarkar et al., 2006; Andrade et al., 2015). Dairy effluent decomposes quickly and reduces the dissolved oxygen level in water streams, resulting in anaerobic conditions that are a breed- ing place for disease-carrying flies and mosquitoes. Studies found that higher concentration of dairy effluents are toxic to many aquatic lives including fish and algae. https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0022029921000819 Downloaded from https://www.cambridge.org/core. IP address: 207.241.231.108, on 27 Jan 2022 at 06:58:10, subject to the Cambridge Core terms of use, available at